Structure and stratigraphy of the Dannemora inlier,

eastern Bergslagen Region  

Primary volcanic textures, geochemistry and deformation 

 

Peter Dahlin and Håkan Sjöström 

Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala 

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Index Introduction .................................................................................................................................................. 4 Geological setting .......................................................................................................................................... 5 Volcanic textures and interpretations .......................................................................................................... 6 Volcanic textures ....................................................................................................................................... 6 Phenocrysts ..................................................................................................................................... 6 Glass fragments and devitrification ................................................................................................ 7 Lithophysae ..................................................................................................................................... 8 Fiamme ........................................................................................................................................... 8 Accretionary lapilli .......................................................................................................................... 9 Pumice block deposit .................................................................................................................... 10 

Discussion and summary of volcanic textures ........................................................................................ 11 Stratigraphy ................................................................................................................................................. 13 Summary of stratigraphic results ............................................................................................................ 16 

Geochemistry and metamorphism ............................................................................................................. 17 Greenstone dikes .................................................................................................................................... 17 Metamorphic conditions ......................................................................................................................... 19 Summary of geochemistry and metamorphism ..................................................................................... 19 

Tectonic structures ..................................................................................................................................... 20 Metavolcanic rocks ................................................................................................................................. 20 Metagranitoids ........................................................................................................................................ 23 Shear zones ............................................................................................................................................. 24 Shear zone displacement .............................................................................................................. 26 

Summary of tectonic structures ............................................................................................................. 26 Dannemora inlier in the regional tectonic framework ............................................................................... 27 Discussion and conclusions ......................................................................................................................... 28 Acknowledgement .................................................................................................................................. 29 

References .................................................................................................................................................. 30  Appendix 1 .................................................................................................................................................. 34 Appendix 2 .................................................................................................................................................. 35  

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Introduction The aim of this project was to build a 3‐4 D structural model for the Dannemora  iron deposit. This model will enable  interpretation of the geometry, stratigraphy, deformation history and genesis of the Dannemora ore deposit. The  low metamorphic grade and exceptionally well preserved primary rock  textures at Dannemora should allow  the construction of a high  resolution model  that can be applied to other more highly metamorphosed ore deposits in Bergslagen. 

The  project was  initiated  by  Lennart  Falk,  Dannemora Mineral  AB,  and  further  developed  by  in particular  Rodney  Allen,  New  Boliden,  with  support  from  Håkan  Sjöström,  Uppsala  University, Magnus Ripa, SGU, and Pär Weihed, LTU, among others. The original application by Rodney Allen and  Håkan  Sjöström  included  two  projects:  1)  The  origin  of  iron  ores  in  Bergslagen  and  their relationships with polymetallic sulphide ores (SGU‐FoU project 60‐1451/2006), and 2) Structure and stratigraphy of the Dannemora iron deposit. This was a collaboration project between LTU, UU, New Boliden  and  Dannemora Mineral  AB,  and  Rodney  Allen.  For  practical  reasons,  this  project  was separated  into  the  two  parts,  but  collaboration  continued.  Structure  and  stratigraphy  of  the Dannemora  iron  deposit  co‐financed  by  Dannemora  Mineral  AB  (main  part)  and  SGU  (SGU‐FoU project 60‐1453/2006). 2009 the project was entirely financed by SGU. 

Two master  theses  sprang  from  the  Structure  and  stratigraphy  of  the  Dannemora  iron  deposit project and  they are attached as appendices. One  thesis  focussed on kinematics of a major shear zone and the deformation mechanisms  in different minerals, a method to deduce the temperature that  prevailed  during  the  tectonic  deformation.  A  third  task  was  to  find  possible  minerals  for radiometric  dating,  both  the  magmatic  and  deformation  ages.  The  second  thesis  deals  with geothermobarometry of sulfides: Fe‐content in sphalerite is pressure dependent and the As‐content in arsenopyrite is temperature dependent. 

Four stops prepared during the research project and by Dannemora Mineral AB, were exhibited  in the Dannemora  area during  the excursion  that  covered  the Bergslagen  region  as part of  the 33rd International Geological Congress 2008. 

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Geological setting The  Bergslagen  region  is  situated  in  the  south‐central  part  of  the  Fennoscandian  Shield  (Fig.  1), which is dominated by metamorphic rock of the GDG‐suite, i.e. granitoid‐dioritoid‐gabbroid, with an age of  c. 1.90‐1.87 Ga  (Stephens  et  al.,  2007).  Subordinate  c.  1.91‐1.89 Ga  are metavolcanic  and metasedimentary rocks and marble, also exist as well as less common younger intrusive rocks, with the age  span 1.87‐1.75 Ga  (Stephens et al., 2007). The Bergslagen  region has been  interpreted  to represent a continental back‐arc magmatic region (Allen et al., 1996). 

The metasupracrustal sequences  in Bergslagen province were deposited mainly as pyroclastic flows (Lundström et al., 1998), in an extensively thinned continental back arc magmatic region (Allen et al., 1996). The Taupo Volcanic Zone in New Zealand, a flooded continental margin dominated by caldera related ignimbrites is the best recent analogy today to Bergslagen (Allen et al., 1996).  

In  the  Dannemora  inlier,  located  in  the  NE  part  of  the  Bergslagen  region  (Fig.  1),  consists  of metavolcanic  rocks  and  marble,  surrounded  by  metagranitoids.  The  metavolcanic  rocks  show textural evidence for being emplaced mostly as pyroclastic currents and subordinate air‐fall deposits (Lager, 2001). The Dannemora ore field  is well known for  its  iron ore, which generally  is hosted by marble that locally contain stromatolitic structures (Lager, 2001). Dating of a pyroclastic flow deposit in the Dannemora inlier gave the TIMS U‐Pb zircon age of 1894±4 Ma (Stephens et al., 2009). 

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Fig. 1. A) Fennoscandian Shield. Bergslagen Region is encircled area. (Modified after Papunen and Gorbunov (1985) andLundqvist (2000)). B) Geological map of the Bergslagen Region. Yellow = metavolcanic rocks, light blue = metasedimentary rocks, GDG = metagranitoids, red, orange and pink = GSDG (granitoids‐syenitoids‐dioritoids‐gabbroids (From Stephens et al., 2007) 

 

Dannemora inlier

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Volcanic textures and interpretations The  metavolcanic  rocks  in  the  Dannemora  inlier  are  among  the  best  preserved  in  Bergslagen (Stephens,  pers.  comm.  2009),  although  the  rocks  have  been  affected  by  greenschist  facies metamorphism and at least two episodes of deformation (e.g. Stålhös, 1991, Stephens et al., 2009). The  composition  of  the metavolcanic  rocks  varies  from  dacitic  to  rhyolitic  and  they  have  been interpreted mainly  as  ignimbrites  (Lager,  2001),  emplaced  by  pyroclastic  density  currents  (PDCs). PDC is the general term for a ground hugging current of gas and clasts, i.e. juvenile, lithic and crystal fragments  (Branney  and  Kokelaar,  2002).  Ignimbrites  are  deposits  of  PDCs  “rich  in  pumices fragments, commonly dominated by poorly sorted beds,  typically made up of various massive and stratified pumiceous beds and some subordinate pumice‐poor beds” (Branney and Kokelaar, 2002). 

Volcanic textures  

This chapter describes volcanic textures and also a texture that  is  lacking  in the Dannemora  inlier. The well preserved microtextures give a hint of the origin of the subsequently metamorphosed and deformed  supracrustal  rocks.  The  textures  were  formed  before  eruption  (e.g.  phenocrysts)  and during  deposition  (e.g.  accretionary  lapilli)  or  after  deposition  (e.g.  spherulites).  Certain  textures provide evidence of the eruption mechanism, emplacement temperature, distance to source region, depositional environment and stratigraphic younging direction etc.  

Phenocrysts The abundance of phenocrysts  can distinguish between different emplacement processes  such as pyroclastic  falls  and  density  currents,  and  also  the  distance  to  the  source.  Distal  pyroclastic  fall deposits  rarely  show  high  abundance  of  phenocrysts  however  they  might  be  part  of  proximal ballistic  deposit.  PDCs  may  carry  crystals  for  long  distances  and  they  can  be  enriched  by  the processes within  currents  due  to  the  abrasion  of  pumice  fragments  containing  crystals  (Walker, 1972). Embayments in phenocrysts form when the growth is  inhibited by mineral grains or bubbles in  the magma  (Kozlowski,  1981).  The  roundness  of  phenocrysts  is  due  to magmatic  resorption (Donaldson and Hendersson, 1988). 

Phenocrysts  are  very  common  in  the metavolcanic  rocks  in  the  Dannemora  inlier. Quartz  is  the dominating phenocryst, usually as 0.5‐5 mm euhedral to subhedral crystals. However roundness and embayment  (Fig. 2A)  in  the quartz phenocrysts, are common and sometimes show polygonization within them (Fig. 2B). Polygonization  is caused by sub‐grain formation during tectonic deformation (Passchier  and  Trouw,  2005).  Subordinate  phenocrysts  are  plagioclase,  mainly  albite,  but  calcic varieties exist locally, which is apparent by subsequent epidotisation (Fig. 3A). 

 

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A   B     Fig. 2. A) Microphotograph of quartz phenocryst with embayment. Scale bar is 0.5mm and crossed polarised light. B)Field photograph of crystal rich ignimbrite containing quartz phenocryst with encircled polygonization. Pencil point for scale. 

A   B   Fig. 3. A) Epidotised plagioclase. Scale bar 1 mm and crossed polarised light. B) Field photograph of pink devitrified, tectonically flattened and rod‐like glass fragments from the lower member. Width of picture 12 cm.  

Glass fragments and devitrification According  to  the  laws of  thermodynamics,  glass  is unstable  (Marshall, 1961)  and hence prone  to devitrification i.e. crystallisation (de Latin for changed from and, vitrum means glass) and alteration (McPhie  et  al.,  1993). High  temperature  devitrification  of  silicic  glass  produce  different  styles  of crystal aggregates of cristobalite and/or feldspars collectively named spherulites (e.g. Lofgren, 1971) and these are characteristic for hot pyroclastic deposits and lavas (Ross and Smith, 1961), but occur in colder deposits too. 

During upwards  transport  in  the  crust  the magma  is  subjected  to progressive decompression and dissolved  gases  start  to  exsolve,  resulting  in  the  onset  of  bubble  formation  and  eventually  to fragmentation  in  the  conduit  (Cashman  et  al.,  2001)  and/or  at  the  surface  (Legros  and  Kelfoun, 2000).  These  fragments  consist  of  glass  shards  and  pumice  (i.e.  juvenile  fragments)  and  their presence  help  distinguishing  pyroclastic  rocks  from  coherent  rocks,  as  the  latter  do  not  usually contain juvenile fragments. 

In pyroclastic deposits hotter than the glass transition temperature (Tg) welding can take place which is  ductile  deformation  of  juvenile  fragments.  The  degree  of  welding  within  pyroclastic  deposits depends on eruption temperature and the retained heat, volatile content, and compression by the overburden (Ross and Smith, 1961). 

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Spherulites have been found in Haglösa, N‐NV of Gruvsjön (Fig. 19) in massive pyroclastic rocks and in  layered,  reworked  epiclastic  rocks,  stratigraphically  located  in  the  lower  member  (see Stratigraphy). Such epiclastic deposits formed due to weathering of rocks to produce new particles different in size and shape from those formed and distributed by an eruption (White and Houghton, 2006). In addition, layered rocks with traction current bedforms set the depositional environment to shallow subaqueous (McPhie et al., 1993). The spherulites have a diameter of < 1 mm and consist of densely packed  radiating mineral  fibres,  and  they  are present both  in  the matrix  (Fig. 4A)  and  in former  large  juvenile  fragments  (Fig. 4B)  in  the pyroclastic  rocks, but only  in  the  fragments  in  the epiclastic rocks. Juvenile fragments contain small spherulites and show welding compaction, clearly around phenocrysts (Fig. 5A). Later the devitrification accentuated the compaction foliation. From a drill core (with uncertain stratigraphic position, possibly lower member) devitrification has produced pectinate spherulites (Fig. 5B), radiating from the surface into the former juvenile fragments. 

Lithophysae Spherulites with a central cavity are called lithophysae (Ross and Smith, 1961) and they start to form at  an  early  stage  of  the  cooling  of  lavas  and  densely welded  pyroclastic deposits  (McPhie  et  al., 1993). Lithophysae have been described from numerous ignimbrite occurrences in Sweden e.g. Lake Rakkur, Norrbotten,  (Lilljequist  and  Svensson, 1974)  and Hällefors, Bergslagen  (Lundström, 1995). This texture is has not been recorded in the Dannemora inlier, indicating that the rocks were neither lavas nor densely welded pyroclastic deposits. 

Fiamme The flattening of pumice fragments and formation of fiamme (Italian for flames) can be ascribed to welding  compaction,  diagenetic  compaction  and/or  tectonic  deformation  in  pyroclastic deposits/rocks (Gifkins et al., 2005). Fiamme formed by welding compaction, has  feathery tips and are ragged compared to diagenetically and tectonically  flattened pumices which have pinched tips (Bull and McPhie, 2007). In low temperature pyroclastic deposits, the glassy fragments are replaced during diagenesis by phyllosilicates  such  as  clay minerals  (McPhie  et  al.,  1993).  The mechanically weak  pumice  fragments  are  easily  eroded  during  the  eruption  and  subsequent  flow.  Abrasion produces  fine ash  that contributes  to  the vast amount of ash  in the so‐called co‐ignimbrite air  fall (Sparks and Walker, 1977). 

In  the Dannemora  inlier parts of  the  lower member contain slightly prolate‐shaped  red  to pinkish devitrified pumice fragments (Fig. 3B). However, welding produces oblate‐shaped fiamme and that would  have  been  folded  by  subsequent  tectonic  deformation  and  not  welding.  Therefore  the prolate‐shape  is most  truly  due  to  tectonic  deformation.  Former  glassy  fragments  in  the  upper member are now sericite aggregates but still show  the primary cuspate‐ and Y‐shape, and  thread‐like  delimitations  (Fig.  6).  The  sericite  replacement  probably  occurred  during  low  temperature metamorphism.  Due  to  the  lack  of  spherulites  in  the  upper  member  it  is  concluded  that  the deposition  was  distal,  emplaced  at  low  temperature  and/or  too  thin  to  retain  the  heat  during welding. 

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A   B   Fig. 4. Microphotographs with crossed polarised light. A) Spherulites growing in the matrix of the pyroclastic deposit. Scale bar is 0.5mm. B) Spherulites growing in the glass fragment of the pyroclastic deposit. Scale bar is 1 mm.  

A   B   Fig. 5. A) High temperature quartz and feldspar replacing pumice fragment with more coarse crystals compared to the matrix. Notice the compaction foliation in the pumice (left side of the black phenocryst), accentuated by grains coarser than the matrix. The coarse grains are due to devitrification. If the pumice is scrutinized numerous spherical spherulites can be discerned. Scale bar 1 mm. B) Micro photo of pectinate spherulites. Crossed polarised light, scale bar is 0.1 mm. 

A   B   Fig. 6. Sericite‐replaced glass fragments with preserved cuspate‐shaped delimitations, from the upper member. Crossed polarised light. A) Scale bar 0.5 mm. B) Scale bar 1 mm 

Accretionary lapilli Huge air suspended ash clouds are produced via fragmentation in and close to the conduit (Cashman et al., 2001, Legros and Kelfoun, 2000) and from elutriation of ash from PDC’s (Sparks and Walker, 1977). Water  drops  falling  through  the  ash  cloud  start  to  accrete  the  ash  to  form  aggregates, accretionary lapilli. Schumacher and Schmincke (1991) distinguished two types of accretionary lapilli; rim and core type.  

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The  record  of  accretionary  lapilli  is  the  only  firm  evidence  for  pyroclastic  fall  deposits  in  the Dannemora inlier (Fig. 7). They have been found at one outcrop in the Dannemora syncline, located in the easternmost part of Gruvsjön. With a maximum diameter of 10 mm for the accretionary lapilli, the estimated ash  cloud  thickness was > 4 km  (Gilbert and  Lane, Fig. 15, 1994) and  this  requires subaerial eruption  (Schumacher and Schmincke, 1991). Consequently  the accretionary  lapilli are  in favour of subaerial eruption although the depositional environment was subaqueous, evident from layers with normal grading and water‐escape structures. 

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Fig. 7. A) Rim‐type (dark rim and light coloured core) accretionary lapilli which are the manifestation of pyroclastic fall deposit. Pencil for scale. B) Microphotograph of rim‐type accretionary lapilli. Scale is 1 mm and parallel polarized light.  

Pumice block deposit During subaqueous emplacement of PDC’s from subaerial or subaqueous eruption, buoyant pumice floats up  the  surface of  the water column. The pumice  stays afloat until  it gets water‐logged and 

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sinks. The  resulting deposit  consists of pumice embedded  in ash  that originates  from both air‐fall and attrition of  the pumice  (Fisher and Schmincke, 1984). As  floating pumice  is easily affected by wind and waves, the formation of a deposit with ash and pumice from the same eruption requires settling of pumice shortly after the eruption or in a constricted area such as a caldera or a lake that hinder the dispersion of the pumice. From subaqueous eruptions in oceans, floating pumice rafts has been reported to travel a great distance from the eruption site (e.g. Shane et al., 1998). Cold pumice absorbs water  slower  than  hot  pumice  (Whitham  and  Sparks,  1986),  because  vacuum  is  created when the hot gas in the vesicles cools and consequently the surrounding sea water is sucked in to fill the empty space in the pumices and they get water‐logged and sink (McPhie et al., 1993). 

North of Bennbo (Fig. 19)  is a bed of phenocryst‐rich pumice blocks  intercalated with ash‐siltstone (Fig. 8). This kind of deposit is an excellent marker bed in metamorphosed and folded metavolcanic rocks. The marker bed also gives a reliable younging direction, in this case grading from non‐layered ignimbrite to the mixture between pumice and ash‐siltstone. Such deposits are quite common in the Skellefte district in northern Sweden (Rodney Allen pers. com 2008).  

 

Fig. 8. Phenocryst‐rich pumice blocks (grey) intercalated with ash‐siltstone (cream coloured), north of Bennbo. The layering is steep to vertical. Stratigraphic younging direction is towards east i.e. down in the figure. Hammer for scale. 

 

Discussion and summary of volcanic textures 

High abundance of phenocrysts indicates deposition from PDC in the lower member. 

McArthur  et  al.  (1998)  concluded  that  in  the  margin  or  distally  in  the  Garth  Tuff,  Wales,  the spherulites were compact, spherical and smaller compared  to  the ones within  the proximal parts. The  pectinate‐shaped  spherulites  occurred  in  non‐welded  to  slightly  welded  parts  (Fig.  9).  The spherical, small and compact spherulites  in the Dannemora  inlier consequently  indicate a marginal 

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or distal deposit. Pectinate‐shaped spherulites are located in the uppermost part of the deposit (Fig. 9),  hence  in  the  E  fold  limb  of  the  anticline,  and  relative  above  the  spherical  type,  indicates  a younging direction towards E. The lower member contain non‐flattened pumice fragments replaced by feldspar i.e. the deposits never got welded. 

Within  the  upper member,  the  juvenile  fragments  still  got  their  original  cuspate  shape  and  are replaced with sericite.  In  the highest  level of  the  stratigraphy consists of marble  intercalated with ash‐siltstone  that  lacks  large phenocrysts,  indicating  air‐fall deposition of  volcanic  ash during  the formation of the carbonate. 

Fiamme  in  the Dannemora  inlier got  their  shape  from diagenetic and/or  tectonic  compaction. No preserved evidence for welding compacted fiamme has been recorded. 

Accretionary  lapilli, present  in  the W  limb of  the Dannemora  syncline,  formed during  a  subaerial eruption but were deposited subaqueously. 

The pumice blocks bed was deposited subaqueous in an isolated sedimentary basin. 

Fig. 9.  Idealised profile of  the Garth Tuff, Wales with  the defined  textural zones. The boundaries between  zones are gradational.  In Dannemora  inlier spherical spherulites occur  in the sparsely spherulitic zone, e.g. Fig. 4, and pectinate shaped  spherulites  in  the  uppermost  part  of  the  ignimbrite,  e.g.  Fig. 5B.  Notice  that  lithophysae  missing  in  the Dannemora inlier grow in the central part of the ignimbrite. (From McArthur et al., 1998) 

 

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Stratigraphy Two synclines (Dannemora and Bennbo synclines) and an  intervening anticline were  interpreted by Lager (2001) (Fig. 19). The ore bearing Dannemora syncline in the E and the Bennbo syncline located c. 2  km  westwards,  both  coincide  with  strong  positive magnetic  anomalies  (Stålhös,  1991).  The anticline west of Gruvsjön (Fig. 19) exposes the deepest part of the stratigraphy. 

A correlation between the two drill cores, 276 and 286, used by Lager (2001) and the drill core, 494, that was drilled approximately 1 km southward and analysed  in this study, would have been  ideal. However most of drill core 286 is missing, which makes  it impossible to correlate the two borehole profiles. 

A valid stratigraphy is vital to determine the position of the ore bodies in and the 3D structure of the Dannemora inlier. Lager (2001) divided the supracrustal succession into upper and lower formation, but  the  boundaries were  not  defined.  The  basis  for  the  division  of  the  stratigraphy  into  a  large number of pyroclastic  flow deposits  is not specified  (Lager, 2001), but colour variation  is the most probable explanation. The numerous beds or  layers of different deposits have not been possible to define  during  drill  core  logging  and  field  work.  The  revised  interpretation  is  based  on  textural changes, which are more reliable to separate different deposits than variation in colour. Earlier work by Lager (2001) was very detailed and he described and interpreted the stratigraphy as very variable with hundreds of “pyroclastic flow deposits or ignimbrites” (the quotation marks was used in Lager, 2001).  Based  on  both  field  observation  and  logging  of  a  c.  1240 m  long  drill  core  494,  that interpretation has been revised in this study. 

The supracrustal succession here referred to as the Dannemora Formation (DFm), is divided into an upper and a lower member (Fig. 10). The members can be correlated with the two volcanic stages of the  evolution  of  the  Bergslagen  region  described  by Allen  et  al.,  (1996):  the  lower member was deposited during the  intense stage and upper member consequently during the waning stage. The lower boundary of DFm  is not exposed and the highest  level of DFm  is exposed  in the cores of the Dannemora and the Bennbo synclines. The  lower member  is subdivided  into subunit 1 (lower) and subunit 2  (upper), each consisting of a  flow deposit  (bottom) and air‐fall deposit with accretionary lapilli (top) (Fig. 10). The partly missing accretionary lapilli deposit in subunit 2 is discussed below.  

The thickness of the DFm is not stated in Lager (2001), but a rough estimate is 700‐800 m (cf. Plate 2 in  Lager,  2001). Based on  logging of  a drill  core 494 which penetrates  the whole  succession,  the thickness of  the DFm  is here estimated  to 600‐700 m. The starting point of  the borehole  is  in  the western  limb of  the anticline  i.e.  in  the  lower member  (Fig. 10). The  two  recorded occurrences of accretionary  lapilli  are  interpreted  as  the  same  bed,  divided  by  the  axial  plane  of  the  anticline (Fig. 10).  If the occurrences  instead represent two separate accretionary  lapilli beds, the estimated thickness is at least 300 m larger and the lower member would have an additional subunit. Another complication  is  that  subunit  2  of  the  lower member  is  > 400 m  thick,  but  as  the  borehole  goes through a parasitic z‐fold (cf. Fig. 4, Lager 2001), the true thickness is consequently < 400 m. 

One key unit has not been recorded during logging of drill core 494; the accretionary lapilli beds that are interpreted as the top of subunit 2 of the lower member (Lager, 2001 and Allen et al., 1996). The borehole  goes  through  the  stratigraphic  level  with  the  accretionary  lapilli  bed  about  450  m 

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horisontal distance  SW of  the outcrop with  the  same bed. A missing bed  can be due  to  faulting, reworking or erosion. No fault breccias or shear zones were recorded during the logging of the drill core. And even if such structures would have been encountered, the true orientation of them cannot be achieved because  there  is no  information about  the borehole orientation available. Reworking and erosion of a deposit might be selective and also cause lateral differences along the beds. 

Fig. 10. Stratigraphic column of Dannemora Formation based on drill core Bh 494 (left). The formation is divided into an upper and a lower member. Subdivision of the lower member is subunit 1 (lower) and subunit 2 (upper). Repetition ofthe  lower member  is due to folding and as the borehole starts  in the western  limb (right)  it crosses the  inferred axial plane.  

Based on profiles drawn from mine plans and the assumption that the ore bearing layers are located in  the  uppermost  part  of  the  succession,  the  axial  trace  of  the  Dannemora  syncline  has  been modified to be located 2‐300 m westward compared to the interpretation by Stålhös (1991).  

In the W limb of the Bennbo syncline, there is an E‐W almost continuously exposed profile showing important  details  concerning  stratigraphy,  depositional  environment  and  tectonic  structures.  The steeply  dipping  layers  contain  numerous  sedimentary  structures  such  as  cross  bedding,  water‐escape structures, soft‐sediment folding and erosion channels (Fig. 11). These structures all show an unambiguous  stratigraphic  younging  direction  towards  E. Water  depth must  have  varied  during deposition as the grain size ranges from silt to coarse sand. The main source of sediments is primary volcanic  deposit  e.g.  a  fiamme‐bearing  layer  and  eroded  and  reworked  volcaniclastic  deposits, evident by quartz crystals. Within fine‐grained parts of the succession, banded iron formation (BIF) is common  (Fig. 11),  and within  the BIF beds  the barium  rich  feldspar hyalophane has been  found. 

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Based on  the  amount of barium, here  c. 8 wt‐percent,  the hyalophane  formed during diagenesis (Essene et al., 2005). It is not known if the occurrence of hyalophane linked to the formation of the BIF. However numerous occurrences of coexisting Fe‐Mn‐mineralisations and hyalophane have been described e.g. Lillsjön, Bergslagen, Sweden (Lundström and Wadsten, 1979), Jakobsberg, Bergslagen, Sweden (Igelström, 1867) and Cuyuna Iron Range, Minnesota, USA (McSwiggen et al., 1994). 

A   B   Fig. 11. A) BIF with soft‐sediment deformed vertical dipping beds, both within the bed and at the upper boundary. N is to the left and younging direction upwards in the picture. Horisontal surface, younging direction is up in the figure and width of view c. 1 m. B) Erosion channel (beige, upper part) cutting down into a reworked layered ignimbrite, with white devitrified pumice fragments. Vertical dipping beds and younging direction is up in the figure. Pencil for scale. 

The occurrences of epidote fragments (Fig. 12) were  interpreted to  indicate marine deposition and also  change of depositional  sequence  (Lager, 2001). They were  considered  to  represent pieces of carbonate lithoclasts replaced by epidote in the pyroclastic flow (Lager, 2001). We suggest that they represent pumice fragments that acted as traps for fluids during alteration and metamorphism. This interpretation is based on the fact that the fragments have the same texture as the matrix including quartz phenocrysts. Epidotisation occur almost exclusively in the vicinity of greenstone dikes, i.e. the alteration might be  related  to the  intrusion event or  the  regional metamorphism of  the dikes and the metavolcanic rocks. 

A    B   Fig. 12. Epidote  fragment  from  the  lower member A) Drill  core. Notice  the quartz phenocrysts within  the  fragment.Scale = top to bottom 3 cm. B) Outcrop. Most obvious epidote fragment is lower left. Black pencil for scale. 

 

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Summary of stratigraphic results 

Dannemora  Formation  is  divided  into  a  lower  and  the  upper  member.  The  lower  member  is subdivided into two subunits. Total thickness is approximately 600‐700 m. However with respect to folding, this approximation is a maximum value. 

The  division  into  hundreds  of  beds  recorded  by  Lager  (2001)  was  probably  based  on  colour variations.  This  division  is  not  supported  by  this  study,  as  textural  changes  are  a more  reliable feature when dividing a succession into units and beds. However, the depositional sequences (Lager, 2001) can to certain degree be correlated to member 1 and 2. 

Epidote  fragments are not  former carbonate  lithoclasts  that  indicate marine deposition. Texturally these  fragments  are  pumices.  The  pumices  acted  as  traps  for  hydrothermal  fluids  during  dike intrusion and/or during regional metamorphism. 

 

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Geochemistry and metamorphism Greenstone dikes 

Numerous  greenstone  dikes  have  intruded  the  rocks  in  the  Dannemora  inlier  and  surrounding metagranitoids. The greenstone dikes are mainly greenish grey  to greyish green, very  fine grained and dominated by epidote and chlorite with minor amounts of amphiboles and sphene. The opaque phase consists of euhedral, scattered < 1 mm pyrite grains.  

Seventeen greenstone dikes have been analysed  for major and  trace elements.  In a TAS diagram, (Fig. 13) they plot as basalt to picrite. In the Nb/Y vs. Zr/TiO2 discrimination diagram they plot as sub‐alkaline basalts (Winchester and Floyd, 1977). 

A  B  Fig. 13. A) TAS‐diagram, the greenstone dikes (n=17) plot as picrite to basalt (boundaries after Le Maitre, 1989).  B) Discrimination diagram Nb/Y vs. Zr/TiO2 of Winchester and Floyd (1977). All analyses, except one, plot as sub‐alkaline basalt. 

The Spider diagram (Fig. 14) of rock/primodial mantle shows that LILE (large lithophile elements), i.e. Ba to K, with one exception, are enriched relative to HFSE (high field strength elements), and that Nb and Ta are depleted. REE normalized to chondrite are enriched  in the LREE compared to HREE that levels  out  below  10x  the  chondrite  values,  and  a  small, mainly  positive  peak  in  europium  with Eu/Eu* = 0.91‐1.29. The latter indicates that plagioclase was not part of the crystallisation. 

A  B  

Fig. 14. A) Spider diagram of rock normalised to primordial mantle. A general enrichment of LILE compared to HFSE, depletion of Nb and Ta. Primordial mantle values after McDonough and Sun (1995). B) REE in rock analyses normalised rock to chondrite, with enrichment in LREE compared to HREE. Eu has a slight positive peak. Chondrite values after McDonough and Sun (1995). 

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In a Y‐La‐Nb discrimination diagram (Fig. 15) the analyses plot in the calc‐alkali basalt field (1A) and continental basalt  field  (2A). Analyses  that plot away  from  the Nb apex are  typical  for subduction related  environment  or  continental  crust  contamination  (Wilson,  1989).  The  cluster  in  the  calc‐alkaline  field  is  in  favour  of  subduction  environment.  However  in  Ti‐Zr‐Y  discrimination  diagram (Pearce and Cann, 1973)  the analyses scatter mainly as WPB  (n=8) and  in  the mixed  field B  (n=5). Stephens  et  al.,  (2009)  concluded  that mafic metavolcanic  rocks  from  Bergslagen  region,  plot  in fields B, C and D  in a Zr‐Ti‐Y diagram  (cf. Fig. 13),  i.e.  some of  the analyses are  classified as  calc‐alkaline formed in an active continental margin environment. 

A   B   

Fig. 15. A) Y‐La‐Nb discrimination diagram of Cabanis and Lecolle (1989), mainly discriminate the analyses as calc‐alkali basalts (1A) and continental basalts (2A). 1C is volcanic‐arc tholeiites and 1B transition between 1A and 1C, 2B is back‐arc basin and field 3 is oceanic basalts. B) Ti‐Zr‐Y discrimination diagram of Pearce and Cann (1973), the analyses scatter within all fields except A. A = Calc‐alkali basalts, B = Ocean‐floor basalts, with low‐K tholeiites and calc‐alkaline basalts, C = Low‐K tholeiites, D = WPB. 

Based on the relation between Ta/Yb and Th/Yb (Fig. 16), the tectonic environment for the analysed greenstone  dikes  scatter within  the  field  defined  for  continental  arc  basalt  (CAB),  within  active continental  margin,  and  within‐plate  volcanic  zone  (WPVZ),  i.e.  a  back‐arc  basin  environment (Gorton and Schandl, 2000). 

Yttrium  can  be  highly mobile  during  alteration  and weathering  resulting  in  depletion  (Hill  et  al., 2000), consequently the sampling here was focussed on fresh and unaltered parts of the greenstone dikes. The mobility and depletion of Y due to alteration should be detected in a Zr‐Ti‐Y‐diagram (Fig. 15)  and  if  altered  the  analyses  plot  away  from  the  Y  apex  and  outside  the  defined  field.  This  is possible  to observe even  for weakly altered samples  (cf. Hill et al., 2000). Mobility of both Zr and TiO2 should be revealed in the same way. The conclusion is that Y, Zr and TiO2 is reliable in tectonic setting  diagrams.  It  should  be  mentioned  that  fractionation  can  result  in  plots  indicating  false tectonic environments. The low Mg# ranging from 25 to 47 is an indication of fractionation. 

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Fig. 16. Discrimination diagram based on Ta/Yb vs. Th/Yb. The analyses scatter within active continental margin and within‐plate volcanic zone. MORB = Middle ocean ridge basalt, SHO = Shoshonite, CAB = Continental Arc Basalt, IAT = Island Arc Tholeiite. (Combined diagram of Gorton and Schandl (2000) and Pearce et al., (1981))  

The Bergslagen region has been suggested to be an extensional continental back‐arc region (Allen et al., 1996). The scatter of the analysed greenstone dikes from Dannemora from CAB to WPVZ could be interpreted as a similar change of tectonic setting, as described by Pearce et al., (1981), i.e. that dikes  intruded both during a back‐arc spreading episode and an arc episode, evident  in changes  in geochemical  affinity.  In  addition,  the  ratio  between  subduction  zone  component  and  MORB component  can  change  over  time  (Pearce  and  Peate,  1995).  The  influence  of  subduction  zone component decreases when  the back‐arc  region  “matures”  into back‐arc  spreading  (Pearce et al., 1981). The depletion of Nb and Ta could be ascribed to subduction related processes (Kelemen et al., 2003). 

Metamorphic conditions 

The  greenstone  dikes  consist  of  actinolite  +  chlorite  +  epidote  ±  hornblende  ±  albite  i.e.  typical greenschist  facies mineralogy  for a basaltic composition.  In  the  rhyolites, prograde muscovite and chlorite coexist along the tectonic fabric, which indicate that the metamorphic grade never reached amphibolite  facies  (Winkler,  1979)  in  the Dannemora  inlier. Deformation mechanisms  in  the ÖSZ (see later text) give temperature ≤ 500°C (Passchier and Trouw, 2005). These findings show that the metamorphism  never  exceeded  greenschist  facies  in  the  Dannemora  inlier,  but  also  that  the previous estimate of lower greenschist facies conditions (Lager, 2001) was too low. 

Summary of geochemistry and metamorphism 

The greenstone dikes from Dannemora inlier and surroundings are geochemically classified by minor elements  as  subalkaline  basalts.  Tectonic  environment  diagrams  classify  these  subalkaline greenstone dikes as arc‐basalts with continental affinity to within‐plate volcanic zone. The trough in Nb/Ta also indicates a subduction related tectonic environment, i.e. an active continental margin. 

On  the basis of both  the mineralogy  in  the greenstone dikes and  the deformation mechanisms  in deformed  rocks,  the  metamorphic  temperature  was  ≤  500°C  i.e.  uppermost  greenschist  facies conditions. 

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Tectonic structures The intrusion of the early orogenic granitoids has previously been suggested to result in the isoclinal folding and  steeping of  the supracrustal  rocks  in  the area as well as  in Bergslagen  in general  (e.g. Stålhös,  1991).  However many  studies  have  shown  that  granitic magma  generally  crystallises  as tabular rather than diapir‐shaped bodies (e.g. McCaffrey and Petford, 1997 and Brown, 1994). Also the  lack of metamorphic aureoles around  the granitoids  contradicts  large diapiric bodies. Already Mahon  (1988) concluded  that granitoid diapirism would suffer “thermal death” and  lock up  in  the middle crust. Therefore the tight (F1‐) folding in the supracrustal inliers in the Dannemora area (and Bergslagen)  must  be  due  to  subsolidus  deformation  affecting  these  rocks  and  the  surrounding granitoids.  The  regional  tectonic  deformation  affected  both  lithologies  and  occurred  after  the intrusion of the granitoids. Stephens et al., (2009) concluded the 1.87‐1.84 Ga GSDG suite  intruded under transtensional regime of regional scale dextral strike‐slip structures. 

It is vital in any study of a structural evolution to identify the number and character of foliations. In this study, three tectonic foliations (S1, S2 and S3) have been recorded in the metasupracrustal rocks in  the  Dannemora  inlier.  Tectonic  foliation  only  localised  to  faults  (Lager,  2001)  is  thus  not supported. A direct correlation of structures with earlier studies  in  the area  (Stålhös, 1991)  is not possible as that work did not separate bedding from tectonic foliation in the supracrustal rocks. This excludes the use of the published data for bedding cleavage analysis to define large‐scale folds, but the differentiation of rock types, intense foliation etc on the map of Stålhös (1991) help outlining the general  trends  of  the  different  rocks  and  also  some  large‐scale  folds.  In  the  ongoing  work  we integrate this data with bedding/cleavage analysis to define F1 and F2 folds. Another important task is to relate shape and localisation of ore/mineralisation to the structural elements. It is implicit that the iron ore is concordant to S0/S1 but also affected by subsequent folding and the development of the  pronounced  lineation.  However,  the  sulphide  mineralisation  in  Svavelgruvan  is  obviously discordant to S0/S1 (Fig. 51 in Lager, 2001) and therefore most likely structurally controlled. 

The record of one major and some smaller ductile shear zones affecting both the plutonic and the supracrustal  rocks  is  the  most  significant  new  structural  element  for  the  interpretation  of  the structural geometry of the Dannemora area. If displacement distances are large this may affect also the  interpretation  of  the  stratigraphy  as  previous  interpretations  are  based  on  a  continuous stratigraphy without tectonic breaks. 

The  absence  of  layering  and  the  less  variable  character  of  the  tectonic  foliations  within  the metagranitoids make  the  definition  of  foliations  less  of  a  problem.  HOwever  the  correlation  of foliation(s)  in  the  plutonic  and  supracrustal  lithologies  is  less  obvious  and  important  for  the structural interpretation. 

Metavolcanic rocks 

S1 is a continuous cleavage defined by sericite/chlorite and is in most cases parallel to sub‐parallel to S0, which is steep and strikes N‐S to NNE‐SSW. The close to isoclinal character of F1 is evident by the small  angle between  S0  and  S1. The most  conspicuous  F1  structure  in  the  area  is  the Dannemora syncline  that  is  slightly  overturned  towards  east.  Locally  a  faint,  moderately  plunging  mineral lineation overprinted by the distinct L2 has been recorded. This faint lineation is probably L1. 

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However, meso‐scale  isoclinal  F1‐folds with  S1  defining  the  axial  planar  foliation  and  verified  by refolding by F2 are only occasionally observed  in  the Dannemora  inlier  like e.g.  in  the Garpenberg area (Allen et al., 2003) and the entire Bergslagen region. The  large‐scale  isoclinal F1 folding of ore bearing  stratigraphy envisaged by mining  is  thus not  reflected by  frequent meso‐scale  structures. This discrepancy is probably significant for the folding mechanism and the structural evolution. 

In the Bennbo area  (Fig. 19) there  is a 100m scale tight F1  fold. The bedding cleavage  relationship between S0 and S1 is reversed in the limbs and way up shifts from E in the western limb to W in the eastern  limb.  The  constructed  fold  axes  is  sub‐parallel  to  the  measured  lineations  in  the  area (Fig. 17)  

S2 is a grain shape fabric, which is most distinct in rocks with quartz phenocrysts, but also present in massive metavolcanic rocks in which S2 results in kinking of S1. The orientation of S2 is mainly WNW‐ESE and  it has a distinct angle to S0 i.e. to the main strike direction of the Dannemora syncline and shear zones (Fig. 19). Within layered varieties of the metavolcanic rocks S2 is related to asymmetric meso‐scale F2‐folds. The pronounced  lineation  in the area  is sub‐parallel to the axes of these  folds hence the lineation is referred to as L2. 

Parasitic  F2‐folds  on  the  geological  map  (Fig.  19)  are  derived  from  different  sources.  In  the Dannemora syncline the z‐fold  is traced from a folded accretionary  lapilli bed from the mine maps (Lager, 2001). The shape of the z‐fold  in the anticline  is based on bedding measurements and that fold closure is > 400 m wide. 

A           B      

Fig. 17. A) Stereonet displaying poles to S0 (filled circles, n=24), S1 (open squares, n=13) and S2 (open triangles, n=10). B) All measured  lineations  in Dannemora  inlier  (diamonds, n=30) with mean vector  (blue circle displaying  the scattering interval) and S1 (open squares, n=13) and the cylindrical best fit (red great circle) for S1. 

The relationship between F2‐folds and thin (< 1 dm wide), ductile shear zones (Fig. 18) indicates that the  latter  formed  during  or  after  D2.  The  strong  dextral  shear  of  WNW‐ESE,  steeply  dipping, greenstone dikes was developed during D2 (Fig. 18). A moderately to steeply plunging lineation (L2), resulting from strong mineral stretching and/or intersection between S1/S2 is parallel to sub‐parallel to the axes of F2. The stretching related to L2 has most probably affected the distribution and shape of the ore bodies. 

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Approximately  N‐S  striking  greenstone  dikes  truncating  the  bedding  show  L2  but  are  also boudinaged.  If  L2  and  the  boudinage  developed  simultaneously,  this  implies  transpressive deformation during that event. 

A   B   Fig. 18. A) Subhorizontal surface showing reworked, graded bedding in steep dipping metavolcaniclastic rock. A possible F1‐fold (highlighted by hatched line) is refolded by an F2 fold with a grain‐shape fabric, axial planar S2. F2 is truncated by a thin dextral shear zone. All structures are cut by the local S3 cleavage (parallel to string of compass; mirror pointing N). B) Greenstone dike with dextral S‐C' fabric (WNW towards left). 

S3 has only been  found  locally.  It  is a moderately dipping, spaced cleavage truncating S1, S2 and F2 (Fig. 18), and the significance of this foliation  is not yet established. S3  is striking 190‐230° which  is roughly the strike of the main shear zone east of Dannemora syncline, but the foliation has a gentler dip. Table 1 shows a summary of structures in the Dannemora inlier. 

Table 1: Summary of structures in the Dannemora inlier 

Geological event  Foliation  Lineation Fold Phase Deposition of the supracrustal rocks and intrusion of 

granitoids 

S0    Syn‐sedimention folds  

Extension 

(?) Intrusion of dikes (?) 

      Extension? 

D1  S1 continuous, defined by sericite/chlorite and parallel with axial plane to F1 

Possibly horisontal and parallel to fold 

axis to F1 

F1 Isoclinal,  

N‐S striking and with steeply dipping axial 

plane 

Compression 

(?) Intrusion of dikes (?) 

  Extension? 

D2  S2 GSF, spaced and 

most pronounced in rocks with phenocrysts 

L2 Stretching‐ and intersection 

lineation between S1/S2 

F2 Asymmetric, z‐folds 

Compression: formation of folds and shear zones 

D3  S3 local 

Compression

  

 

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Metagranitoids 

The metagranitoids  surrounding  the Dannemora  inlier  share  a more or  less pronounced  lineation with the supracrustal rocks (this study and Stålhös, 1991) suggesting that it corresponds to L2 in the latter. The steep foliation to the W of the magmatic contact to the supracrustal rocks  is partly at a high angle to the general NNE‐SSW trend of the rocks of the inlier and parallel to the strike of S2 in the  latter. These patterns  indicate  that  the granitoids and  the  rocks of  the  inlier were affected by approximately N‐S shortening during D2 and that the  foliation subsequently rotated  into the shear 

 

Fig. 19. Top ‐ Map of the Dannemora inlier. Inferred F1 synclines (X) and anticline (<>) with asymmetric F2‐fold. Simplified map from 12I Af161 Östhammar NV (Stålhös, 1991). Bottom – A schematic NW‐SE profile across the Dannemora inlier as follows from A to B: metagranitoid in the west with “baked” contact to the metavolcanic rock. Next is the Bennbo syncline with marble recorded only in the western fold limb and the anticline west of Gruvsjön (see top figure). The contact between the metagranitoid and the metavolcanic rock west of the Dannemora syncline is sheared with east‐up movement. In the deepest part of the syncline there is a granitoid intrusion with skarn‐envelope, known from drill core logging. The relationship between this intrusion and the one immediately to the west is unknown. The Dannemora syncline consists of intercalations of marble and metavolcanic ash‐siltstones. The regional scale shear zone (ÖSZ, see below) defines the contact to the metagranitoid in the east. 

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zone. Alternatively the shear zone is an earlier structure that has been rotated clockwise by folding, as suggested by Persson and Sjöström (2003). 

Shear zones 

The northwards extension of the Österbybruk‐Skyttorp zone, ÖSZ, (Persson and Sjöström, 2003) has been identified east of Lake Filmsjön. The ÖSZ belongs to a shear zone system splaying off from the Singö  Shear  Zone  in  the  north  (Persson  and  Sjöström  2003).  The  system  is  folded  (rotated anticlockwise) and continues E‐W along the supracrustal rocks including the Ramhäll ores, ca. 12 km S of Dannemora. This folded shear zone system makes up the western and southern boundary of a major tectonic lens of metagranitoids. Its eastern boundary is outlined by the Gimo Shear Zone (GZ) Persson  and  Sjöström,  2003).  The  ÖSZ  and  the  GZ  appear  distinct  in  regional  formlines  pattern (Fig. 20) (Bergman et al., 1996). 

The  steep  ÖSZ  truncating  the  inlier  east  of  Lake  Filmsjön  is  at  least  500  m  wide  and  affects granitoids,  rhyolites and basalt  (cf. Stålhös, 1991). The  lineation  in  the mylonites  is often  steeper (more down‐dip) than in the surrounding, less deformed rocks. The foliation in the granitoids rotates clockwise approaching the shear zone truncating the eastern margin of  the  inlier.  In that part  it  is parallel to the general trend of the rocks of the inliers. To the E of the shear zone, the foliation in the metagranitoids rotates anticlockwise from NNE‐SSW to E‐W in an at least c. 3 km wide zone (Fig. 20). The latest and dominating ductile movement of the shear zone east of Lake Filmsjön is E‐up, which is in agreement with earlier work  to  the S  (Engström 2001, Persson and Sjöström, 2003). Hence  the granitoids to the E have been uplifted relative to the  inlier. Ductile shear structures have also been recorded underground  in  the mine at 175 m  level. Way up structures  towards NW show  that  this shearing occurred in the eastern limb of the Dannemora syncline. 

A  revised excerpt  from a master  thesis by  Linn Björbrand describes  the microtextures of  the ÖSZ (Appendix 1). 

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 Fig. 20. Map of formlines and interpreted deformation zones in NO Uppland (Bergman et al., 1996). 

The mine map  of  Konstängsfältet  shows,  that  seven  drill  cores  truncated  “skölzoner”.  As  ductile shear zones are apt to be reactivated  it  is very  likely that at  least some of these semi‐brittle shear zones (“skölzoner”) formed by reactivation. Therefore, the ductile shear zone system in the eastern limb  of  the  Dannemora  syncline  probably  influenced  the  location  and  orientation  of  the subsequently developed  semi‐brittle  system.   Such  repeated activity has been  recorded along  the shear zone between Skyttorp and Vattholma (Engström, 2001).  

Also the tabular granitoid W of the Dannemora syncline and S of Gruvsjön is mylonitised (along both boundaries) and shows again E‐up kinematics.  In addition, the tabular granitoid at Film, possibly the same as at Dannemora, is strongly deformed at its western margin. This repeated structural pattern suggests that E‐up shear zones significantly affect the eastern part of the Dannemora inlier, including the Dannemora ore bearing syncline. Also in Garpenberg in northern Bergslagen (Allen et al., 2003) and  Viker‐Älvlången  in  the  southwest  (Stephens  et  al.,  2001),  there  are  approximately  NE‐SW striking shear zones truncating the eastern limb of the ore bearing synclines. 

The  regional consistency of  shear  zones probably affected  the  local distribution of ore bodies but may  also have  contributed  to  the unusual  fold  geometries  and  their  relation  to  the pronounced, often steep lineations typical of Bergslagen. 

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Shear zone displacement The lack of marker horizons on each side of the ÖSZ makes it impossible to get a direct measurement of the displacement during ductile shear.   However,  it  is possible to get an estimate by comparing the mineralogy and  in particular  the mineral chemistry  in similar  rocks across  the shear zone. The titanium  content  and  Fe/Fe+Mg  in  biotite  (Henry  et  al.,  2005)  in  comparable  granodiorites complemented by plagioclase‐amphibole thermometry  in dikes on each side will be applied to give at  least a crude estimate. A study of  the dikes seems most promising  in  this context as  they have greenschist  facies  mineralogy  in  the  inlier  (see  next  paragraph)  and  a  more  amphibolitic  field appearance in the granitoids to the E of the ÖSZ.  

An  eastwards  increase  in metamorphic  grade  is  indicated  in  the  study  by  Persson  and  Sjöström (2003)  showing  that  the  shear  zone  related mineralogy  in  the GZ  indicated  higher metamorphic grade than that of the ÖSZ. In addition, to the SE, in the Norrtälje synform, there are migmatites and anatectic  granitoids  (Stephens  et  al.,  2007).  This  pattern,  and  the  thermobarometry  result  by Sjöström and Bergman (1998) indicate an increase in metamorphic grade both to the NE (the Singö shear zone) and SE. Combined with  the suggestion of a west‐vergent  fold  front  (Stålhös, 1991) or thrust (Sjöström et al. 2008) in the Norrtälje synform, structurally controlled metamorphic variations in NE Bergslagen may  therefore exist although metamorphism outlasting deformation  is a general feature (Allen et al., 1996). This contradiction may reflect that Bergslagen has been affected by two metamorphic episodes as suggested by Andersson et al., (2006). 

Summary of tectonic structures  

It is vital in any study of a structural evolution to identify the number and character of foliations. In this study, three tectonic foliations (S1, S2 and S3) have been recorded in the metasupracrustal rocks in  the  Dannemora  inlier.  Tectonic  foliation  only  localised  to  faults  (Lager,  2001)  is  thus  not supported. 

The at  least 500 m wide  continuation of  the ÖSZ affecting both  the plutonic and  the  supracrustal rocks along the E limb of the Dannemora syncline is the most significant new structural element. 

S1  is a sericite/chlorite defined continuous cleavage,  in most cases parallel to sub‐parallel to S0,  i.e. steep and strikes N‐S to NNE‐SSW. 

S2 is a grain shape fabric, which is most distinct in rocks with quartz phenocrysts, but also present in massive metavolcanic rocks in which S2 results in kinking of S1. 

S3 has only been found locally, is spaced and has a moderately dip. 

A moderately  to  steeply  plunging  lineation  (L2),  resulting  from  strong mineral  stretching  and/or intersection between S1/S2 is parallel to sub‐parallel to the axes of F2. The stretching related to L2 has most probably affected the distribution and shape of the ore bodies. 

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Dannemora inlier in the regional tectonic framework The  regional  tectonic  framework  surrounding  the Dannemora  inlier  is  fairly well  established  and defines  boundary  conditions  for  the  evolution  also  within  the  inlier.  The  northern  margin  of Bergslagen region, although its location at the present erosion level is discussed, probably coincides with  crustal  scale  tectonic  boundaries.  The  Singö  shear  zone  (SSZ)  in  the  NE  was  pervasively deformed at 1.86‐1.85 Ga and shows evidence of  localised deformation 1.83‐1.80 Ga (Hermansson et al., 2008a; Hermansson et al., 2008b). Högdahl et al. (2009) suggested that the SSZ and the Gävle‐Rättvik zone (GRZ) (Tirén and Beckholmen 1990, Stephens et al., 1997) are both parts of a coherent arcuate  structure  defining  the  northern  boundary  of  the  Bergslagen  region.  In  addition,  it  was suggested  that  this  boundary  is  related  to  structures  in  the middle  and  lower  crust  and possibly represents a terrane boundary, which is in accordance with the interpretation that a terrane or plate boundary exist in this part of the Fennoscandian Shield (Lahtinen et al., 2005).  

In a local study Persson and Sjöström (2003) identified the ductile shear zones in the in Österbybruk‐Skyttorp and Gimo areas, the ÖSZ and GZ, respectively, and interpreted these as enveloping a large scale tectonic lens or lenses consisting of granitoids. Steeply plunging east‐verging folds (F3) refolded this patterns and the strong stretching lineation (L2). Several such east‐verging large‐scale folds exist to the south of the GRZ‐SSZ  indicating a common evolution  including dextral shear. Högdahl et al., (2009) suggested that that there was a progressive evolution from dextral shear at 1.87—1.86 Ga to pure  shear  along  the GRZ‐SSZ  and  that  this  resulted  in  shift of  activity northwards  to  the Hagsta Gneiss Zone (HGZ) at 1.81 Ga. Such a progressive evolution is consistent with c. N‐S shortening and (growing)  regional  transpression. Also  the  large‐scale  fold  structure of western Bergslagen, with a clockwise rotation of lithologies approaching the GRZ is consistent with such an evolution. 

All  these  structures  are  mainly  related  to  shortening  of  the  crust,  i.e.  the  evolution  after  the extension of the continental crust that was related to the back‐arc magmatism and ore formation. It is implicit that this extensional period generated large‐scale (listric?) faults that, despite voluminous intrusion  of  granitoids,  represented  crustal  anisotropies  localizing  strain  (e.g.  by  fault  inversion) during  subsequent  crustal  shortening.  Inversion of extensional  faults during  significant  shortening could be expected to result in thrusts rotating to steep reverse shear zones like the ÖSZ. 

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Discussion and conclusions The supracrustal succession is here referred to as the Dannemora Formation and it is divided into a lower  and  an upper member,  and  the  former  is  subdivided  into  subunit 1  and 2.  The deposition environment is not as variable as suggested by Lager (2001). And the 1000’s of thin beds recorded by Lager (2001) was probably based on colour variation rather than textural variations. The occurrence of  epidote  lithoclasts,  interpreted  as  former  carbonate  fragments,  as  an  indication  of  marine environment  (Lager,  2001)  is  not  supported  by  this  study,  because  these  epidote  fragments texturally  resemble pumices.  In addition  the epidotisation  seems  to be  related  to  the  intrusion of dikes and/or regional metamorphism. 

Depositional  temperature and processes were different  in  the  lower and  the upper member. The lower member  contains  small,  scattered,  spherical  and  pectinate  spherulites,  indicating  distal  or marginal parts of a non‐welded to slightly welded pyroclastic flow deposit. The upper member never underwent  any welding, which  is  evident  by  preserved  bubble‐walled  and  cuspate  former  glass shards that were later replaced by sericite. 

The recorded fiamme were flattened due to diagenetic and/or tectonic deformation.  

The size of the accretionary lapilli in Dannemora inlier is in favour of subaerial eruption (Schumacher and Schmincke, 1991) although the depositional environment was subaqueous, evident from layers with normal grading and water‐escape structures. 

Beds with pumice blocks  indicate  subaqueous deposition  in  an  isolated basin.  Floating pumice  is easily dispersed and, for such a deposit to form, it has to be emplaced in an isolated basin or if the pumice blocks sank instantaneously, after eruption close to the eruption site. 

Based  on  the  geochemistry  of  the  greenstone  dikes,  the  tectonic  setting  was  as  the  transition between ACM  and WPVZ,  i.e.  a  subduction  zone  and  a back‐arc basin.  The  greenstone dikes  are classified  as  subalkaline,  generally with  a  continental  affinity.  The  strong  deformation  of  certain greenstone dikes  indicates  that  they  intruded before D2. Different  cross  cutting  greenstone dikes have  been  affected  by  folding  or  formation  of  boudinage,  i.e.  their  original  orientations  were different. 

The interpretation that tectonic foliations are only related to faults (Lager, 2001) can be rejected, as three different foliations except the bedding, has been identified. 

The boundary between the metagranitoids along the western margin of the Dannemora  inlier and the metasupracrustal rocks is magmatic, ~500 m wide, and most of the recorded contacts elsewhere show evidence of tectonic deformation. 

The eastern  limb of  the Dannemora ore‐bearing syncline  is  truncated by a major shear  zone with E‐up kinematics during the  latest ductile deformation. This shear zone represents the continuation of  the ÖSZ by Engström  (2001)  and Persson  and  Sjöström  (2003).  It  affects  the  granitoid  along  a < 500 m wide zone, evident from formlines (Bergman et al., 1996). 

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The metamorphic mineralogy and  the deformation mechanisms  in  the mylonites  in  the ÖSZ show that the metamorphic grade in the area is uppermost greenschist facies, not lower greenschist facies as suggested previously (Lager, 2001). The metamorphic mineralogy of the greenstone dikes  in the Dannemora  inlier and  the mineralogy of  the amphibolitic dikes  in  the granitoid  to  the east of  the shear zone provide a possibility to estimate displacement on the ÖSZ. 

The  recognition  of  shear  zones  (mylonites)  along  the boundaries of  the  tabular  granitoids  in  the eastern part of the inlier implies that the structural geometry as well as rock and ore distribution is overprinted and affected not only by F1 and F2 folds but also an additional tectonic component that must be accounted for in the 3D‐modelling of the inlier.  

There may be  structural  link between  folding  and  shearing.  The  record of  shear  zones  at  similar structural positions at Garpenberg and Viker–Älvlången  in addition to the sheath folds  in the Singö shear zone  (Stephens et al., 2009) suggest that shearing may have resulted  in sheath  folds.  If so a conventional  fold  interference pattern cannot be expected. The  fold axes of sheath  folds are bent but the related stretching  lineation may be fairly constant. The relationship between fold axes and lineations will vary systematically. To address that problem we will aim at defining the orientation of fold axes and lineations along the stratigraphy (the axial traces of F1). 

The  foliation  in  the granitoids  is at  least partly  corresponding  to S2  in  the  supracrustal  rocks. The orientation  of  S2  indicates  approximately N‐S  shortening  and  fits  into  the  scenario  suggested  by Högdahl et al., (2009) to the north of the Gävle‐Rättvik zone (GRZ) at 1.81 Ga.  

Acknowledgement 

We owe Lennart Falk, Dannemora Mineral AB, many thanks for inviting and encouraging us to study the Dannemora area. Lennart’s enthusiasm not only  initiated this study, but also a new generation of ore related research in the Bergslagen region. 

This study has benefitted greatly from the work by Ingemar Lager. 

This project was financed by SGU and Dannemora Mineral AB. Rodney Allen is acknowledged as the second supervisor and an excellent field work and drill core logging advisor. The continuous support by Magnus Ripa, SGU, is acknowledged. 

Next  acknowledgement  goes  to  the  people  at  Dannemora  Mineral  AB,  Lena  Landersjö,  Peter Svensson and Mikael Eriksson for being so helpful and encouraging. 

We would also like to thank the geologists at Boliden Mineral in Garpenberg for hosting a workshop and excursion during the project. 

A  last thank you goes to Karin Högdahl  (Uppsala University), Katarina Persson‐Nilsson and Michael Stephens (SGU) for input and discussion during the excursion to Dannemora, the 23rd of September, 2009. 

30 

 

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1

Appendix 1 Revised excerpt from master thesis by Linn Björbrand

2

Results – thin-sections The following section contains results from thin-section analyses from sheared rock samples and undeformed wall rocks.

Volcaniclastic rocks Ten samples of volcaniclastic rocks are used in this study (001A, 017-A, 017-B, 026-C, 036-I, 036-II, 038-A, 077-B, 091-A, 092-A). All of them have quartz and feldspar as the main mineral assemblage, while 001A, 017-A, and 092-A also has plagioclase as a main mineral. The accessory minerals are chlorite, mica, and opaque minerals. Sample 091-A has microcline as an accessory mineral. Epidote occurs as small grains in 001A, and 036-I, but in 077-B there are porphyroclasts of epidote. In one sample (no. 026-C), a few heavily deformed pyroxene grains exist. The Fe-oxide hematite occurs in sample 036-I, 036-II, and 077-B. Zircon and titanite are two dateable minerals that exist in the samples, zircon in sample 001A and 038-A, and titanite in sample 077-B. The foliation is defined by chlorite as a grain preferred orientation in thin section 001A, 038-A, 077-B. Mica and chlorite defines the foliation in sample 017-A, 017-B, 036-I. Only mica defines the foliation in sample 036-II. A grain preferred orientation of quartz and feldspar in the matrix defines the foliation in sample 091-A and 092-A. Present in thin-section 026-C is a lineation defined by chlorite.

Quartz is deformed by subgrain formation, undulatory extinction, embayments, and brittle fracturing in thin-section 001A, 017-A, 026-C, 036-1, 036-II, 038-A, while 077-B, 091-A, and 092-A lack embayments. Sample 017-A and 092-A also show triple points in quartz, while sample 001A, 017-A, 026-C, 036-II, 038-A, 091-A, and 092-A also show bulging. In sample 001A, 026-C, 036-I, 036-II, 038-A, 091A, and 092-A feldspar is deformed by twinning of plagioclase (lamellar), and simple twinning for the other feldspars. No twinning of feldspar in 017-B. The feldspar porphyroclasts show brittle fracturing and undulatory extinction in sample 001A. Sample 017-A, 026-C, 036-I, 036-II, 038-A, and 077-B show brittle fracturing and subgrain formation, while thin section 091-A only show subgrain formation, and thin section 092-A only show brittle fracturing.

Shear sense indicators occur in sample 001A, 017-A, 017-B, 036-I, 036-II, 038-A, 077-B, while no shear sense indicators occur in sample 026-C, 091-A, and 092-A.

The shear sense indicators in the thin-sections are foliation deflection (001A, 036-I, 036-II, and 038-A), σ-type porphyroclasts (001A, 017-A, 017-B, 036-I, 036-II, and 077-B), mineral fishes (001A, 036-I, and 038-A), and C´-type shear bands (017-A, 017-B, 036-II, and 077-B). All the samples are showing a dextral movement except 017-A, which show both dextral and sinistral movement, and 017-B which show sinistral movement. When the samples are orientated they are all showing east-side up kinematics.

3

A B

C D

E F

Fig. 12: A) Zircon, 001A B) Purple chlorite C) Embayment + brittle fracturing, quartz D) Dextrally sheared porphyroclast 077-B E) Porphyroclast, dextrally sheared, 077-B F) Undulatory extinction of quartz grain, 001A

Granitoid Granitoid samples from the study area are no. 052, 075, and 093. The mineralogy of the samples has small differences. They all contain quartz, feldspar, biotite, chlorite, and epidote. Sample 052 and 093 also contain microcline and plagioclase, while sample 075 also contains calcite, fluorite, and pyroxene. The lineation in sample 052 is defined by biotite, in sample 075 the lineation is defined by chlorite, and in sample 093 the lineation is defined by both chlorite and biotite. The biotite in sample 093 is more preserved than in the other granitoids, also the epidote/muscovite is well preserved. Quartz is deformed by brittle fracturing, undulatory extinction, subgrain formation, and bulging in all three samples. Triple points also occur between quartz grains in sample 052 and 075. None of the samples show any good kinematic indicators.

4

Metamorphic rock (sample L07-1B) The main minerals are biotite and epidote, with quartz, plagioclase, chlorite, calcite, muscovite, opaque minerals, and zoisite as accessory minerals. Biotite defines the foliation. A fracture contains the vein-minerals feldspar and muscovite. This sample contains relict porphyroblasts of epidote and feldspar. Subgrain formation, undulatory extinction, and triple points occur in quartz. Plagioclase show lamellar twinning.

Metabasalt There is one sample of sheared metabasalt from the area, no. 076. The main minerals are amphibole, biotite, and feldspar, with chlorite, epidote, quartz, opaque minerals, and zoisite as accessory minerals. The foliation is defined by chlorite and amphibole by a grain-preferred orientation. Subgrain formation and undulatory extinction are deformation mechanisms in the quartz grains. Feldspar and amphibole show brittle fractures, and amphibole also show subgrain formation. Shear sense indicators are dextral foliation deflection and dextral δ-type and σ-type porphyroclasts of feldspar. The dextral sense of shear gives east-side up kinematics.

Amphibolite The two amphibolitic rocks in this study are sample no. L07-1A-I and L07-1A-II, which both are taken within the shear zone. They both contain amphibole and epidote as main minerals and plagioclase, quartz, chlorite, calcite, and opaque minerals (more in sample L07-1A-II) as accessory minerals. Only sample no. L07-1A-I contains zoisite. The foliation is defined by a slaty cleavage with a grain-preferred orientation of chlorite and amphibole. Lamellar twinning of plagioclase occur in both samples, while twinning of calcite occur only in sample L07-1A-I. Subgrain formation is common in the quartz crystals, which also show undulatory extinction, and triple points between the grains. The kinematics in the amphibolites indicates dextral movement of quartz and amphibole porphyroclasts, and both dextral and sinistral C´-type shear bands. The predominant dextral sense of shear in the amphiboles gives a west-side up kinematics.

Fig. 14: Dextral polycrystalline sigmoid of quartz in sample L07-1A.

Diorite/Gabbro Thin section 091-B is the only sampled Diorite/Gabbro in the area and it contains mainly amphibole, with calcite, chlorite, epidote, quartz, and opaque minerals as accessory minerals. The foliation is defined by amphibole as a grain-preferred orientation. Deformation mechanisms in amphibole are brittle fracturing and simple twinning, while the calcite grains are deformed by lamellar twinning. σ-type porphyroclasts of amphibole show dextral movement, and dextral boudinaged amphiboles also occur.

Ultramafite Only one Ultramafite exists among the thin-sections (092-B) and contains mainly amphibole and feldspar, with epidote, chlorite, quartz, and muscovite as accessory minerals. A grain preferred orientation of amphibole defines the foliation. Amphibole shows deformation by brittle fracturing, undulatory extinction and simple

5

twinning. Indications of both dextral and sinistral movement occur, by σ-type porphyroclasts of amphibole, boudinaged feldspar, and C´-type shear bands. But slightly more indicators for dextral movement exist, which gives an east-side up movement.

Discussion

Volcaniclastic rocks In sample 077-B foliation is defined by sericite. The occurrence of the deformation mechanisms subgrain formation in sample 077-B, the metamorphic conditions were medium-grade for this mylonite (Passchier and Trouw, 2005).

Core-and-mantle structures occur in quartz in thin-section 077-B. It is a single crystal surrounded by fine-grained mantle material (also quartz), developed by dynamic recrystallization in the outer shell of a large single crystal because of intracrystalline deformation. Core-and-mantle is common in low to medium-grade rocks (Passchier and Trouw, 2005).

All thin-sections contain brittle fracturing, undulatory extinction, and subgrain formation of quartz, and that indicate deformation at a ≤ 500° C. Bulging is another deformation mechanism that occur in all samples, except 036-I, where it might have been overprinted by later deformation. Bulging indicate deformation at ≤ 500° C (Passchier and Trouw, 2005). Static deformation has occurred in sample 092-A after the dynamic recrystallization, evident in triple junctions between the quartz grains. The feldspar grains contain lamellar- and simple twinning, which indicates deformation in the low temperature range (Passchier and Trouw, 2005).

Feldspar show brittle fracturing and undulatory extinction in sample 001A, while brittle fracturing and subgrain formation are the mechanisms in sample 026-C, 036-I, 036-II, 038-A and 077-B. 091-A only show subgrain formation and 092-A only show brittle fracturing. The subgrain formation in feldspar indicates a temperature range between 600-825°C (Passchier and Trouw, 2005), which means deformation in lower amphibolite facies for most of the volcaniclastic rock samples. 001A and 092-A show indications of a maximum temperature of 500°C, because of the subgrain formation in quartz, which means deformation in middle- to upper greenschist facies. For the volcaniclastic rocks, the metamorphic grade and deformation mechanisms are the same for the sheared samples as for the non sheared samples.

Shear sense indicators exist in all the volcaniclastic rocks/rhyolites except in sample 026-C, 091-A and 092-A. σ-type porphyroclasts in all samples except 038-A, minerals fishes in 001A, 036-I, and 038-A, foliation deflection in 001A, 036-I, 036-II, and 038-A, and C´-type shear bands in 017-A, 017-B, 036-II, and 077-B. Dextral movement occur in all the samples except no. 017-B, which show sinistral movement. However, 017-A shows both dextral and sinistral movement. After orientation they all have an east side up direction of the movement.

Sample 001A is horizontal, so it is not possible to say anything about the vertical movement, but with a right lateral horizontal movement.

Granitoid Quartz in this sample show many deformation mechanisms, brittle fracturing, subgrain formation, undulatory extinction and bulging. Bulging (BLG) recrystallization in Quartz and undulatory extinction indicate a low temperature, but this sample also show brittle fracturing (below 250°C) and subgrain formation (400-500°C). These mechanisms give a maximum temperature of 500°C (Passchier and Trouw, 2005), and probably earlier deformation is still visible in the rock. Maximum metamorphic grade during deformation were therefore middle- to upper greenschist facies (Yardley, 1989). Static recrystallization has also been a mechanism in the process after deformation, because of triple points between the quartz grains. Reaction symplectite occur in sample 093, (Fig. 13) between muscovite and an opaque phase. Symplectite is thought to be formed because of rapidly proceeding reactions or lack of fluids that can transport material from and towards the reaction nucleus

6

(Passchier and Trouw, 2005). The sericite (fine-grained mica) in this thin-section is an alteration mineral in plagioclase, probably due to hydrothermal alteration.

No convincing shear sense indicators are visible in these thin-sections, so probably the granitoids have not been subject to any shear deformation.

Fig. 13: Muscovite and opaque phase symplectite, sample 093

Metamorphic rock (sample L07-1B) The dominance of mica and epidote in the thin-section indicates that the original rock type might have been mica schist or epidote-mica schist. This rock contains subgrain formation and undulatory extinction of Quartz, which gives a maximum temperature of 500°C. The absence of brittle fractures indicates either a minimum temperature of 250°C, or that the brittle fractures have been overprinted by later deformation (Passchier and Trouw, 2005). The temperatures gained from deformation mechanisms gives maximum upper greenschist facies (Yardley, 1989). Triple points formed between the Quartz grains by static recrystallization after deformation (Passchier and Trouw, 2005). No shear sense indicators in the thin-section indicate that the rock might not be a part of the shear zone.

Metabasalt Quartz shows no brittle deformation in this thin-section, which means that the temperature must have been over 250°C or the fractures have been overprinted by later deformation. Undulatory extinction is dislocations distributed over the crystal, while subgrains are dislocations separating two volumes of crystalline material with the same composition. Those mechanisms indicate a temperature between 250-500°C (Passchier and Trouw, 2005). Both the Feldspars and the Amphiboles show brittle fracturing, which for feldspar means a temperature below 400°C and for amphibole a temperature up to 650-700°C (Passchier and Trouw, 2005). The maximum temperature during deformation was 500°C, indicated by the subgrain formation, which give a maximum of upper greenschist facies metamorphic conditions (Yardley, 1989). Shear sense indicators in feldspar show a dextral movement, which after orientation gives east side up direction of the movement.

Amphibolite Zoisite is a calcium and aluminum rich mineral belonging to the epidote group (MacKenzie and Guilford, 1980). The mineral is common in amphibolites derived from regionally metamorphosed basic igneous rocks and is stable up to amphibolite facies where it forms anorthite and vapor (Deer, Howie and Zussman, 1997).

It can only be seen in sample L07-1A-I because that sample might have metamorphosed under slightly higher temperature. Undulatory extinction and subgrain formation in Quartz indicates a temperature at maximum 500°C (Passchier and Trouw, 2005). Triple points in Quartz forms by static recrystallization, which means that they formed after deformation (Vernon, 2004). Twinning of calcite in the Amphibolites occurs sporadically in only one of the samples, which indicates that the temperature were over 250°C when the amphibolites were

7

deformed (Passchier and Trouw, 2005). The amphibolites were deformed at a maximum temperature of 500°C, maximum upper greenschist facies (Yardley, 1989). Both sinistral and dextral movement is recorded in the samples, with a predominant amount of dextral indicators. It is not uncommon with both senses of shear, usually the movement is not consistent throughout the whole deformation period and therefore one single thin-section can show both sinistral and dextral sense of shear. The dextral shear sense gives a west side up direction of the movement.

Diorite/Gabbro Amphiboles in the Diorite/Gabbro show brittle fracturing and simple twinning, and the calcite grains show lamellar twinning. The brittle fracturing in Amphiboles indicates a temperature below 650-700°C (Passchier and Trouw, 2005). Straight simple twinning of the amphiboles is called kinking and indicates mechanical twinning at low temperature. The calcite twins are straight, tabular, and lamellar, which indicates low temperature at around, 200°C (Passchier and Trouw, 2005). With the wide variety of possible temperatures, it is hard to say anything about the metamorphic grade, but not higher than upper greenschist facies because of the chlorite in the thin-section. Shear sense indicators in this sample show dextral movement, but without orientation no direction of the movement can be obtained.

Ultramafite Amphiboles in the Ultramafite show brittle deformation, undulatory extinction, and simple twinning. Amphiboles are brittle below 650-700°C. At low temperature (below 650-700°C) and/or high strain rate, amphiboles can also deform by deformation twinning. The undulatory extinction in Amphibole is due to recovery by dislocation creep which is active from upper greenschist facies or at higher temperatures.

Therefore the metamorphic grade could be slightly higher than for the other rock types in the area, maybe at least at upper greenschist facies (Passchier and Trouw, 2005). The shear sense indicators in the Ultramafite show both sinistral and dextral movement, with slightly more indicators for dextral movement. That gives, when orientated, east side up kinematics.

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Conclusions

Metamorphic grade • Overall deformation mechanisms (subgrain formation, undulatory extinction, bulging, and brittle fracturing)

show deformation under upper greenschist facies condition (max 500° C). • The microstructural results indicates that the ductile shear zone E of the Dannemora area are the continuation

northwards of the ÖSZ from the Vattholma-Skyttorp fault zone, which fits well with the upper greenschist facies conditions for the ÖSZ.

Kinematics • Overall the kinematics in the area is east-side up, except for the amphibolites which show west-side up

kinematics. • An east-side up pattern for the Skyttorp-Vattholma fault zone and ÖSZ, with a later west-side up deformation,

maybe occurring prior to Ordovician or Silurian fits well with the interpretation of an east-side up pattern in the Dannemora area.

Zircon and titanite • Titanite is found, but only a few grains have been recorded. • Zircon exists as larger grains than the titanite crystals and occurs more frequently. The grains are better

preserved than the titanite.

References

Deer, Howie and Zussman, 1997. Disilicates and Ring Silicates, volume 1B (second edition). The Geological Society, UK 623p.

MacKenzie W.S and Guilford C., 1980. Atlas of rock-forming minerals in thin section. Halsted Press USA 97p.

Passchier, C.W and Trouw, A.J., 2005. Microtectonics (Second Edition). Springer-Verlag, Berlin 306p.

Vernon R. H., 2004. A practical guide to Rock Microstructure (First edition). Cambridge University press UK 474p.

Yardley Bruce.W.D, 1989. An introduction to metamorphic petrology. Longman Group UK 222p.

9

Thin-section descriptions

The following section contains descriptions of the analysed thin-sections.

L07-1A-I (Amphibolite) The main minerals are amphibole, and epidote, with quartz, plagioclase, chlorite, calcite, opaque minerals, and zoisite as accessory minerals. Chlorite shows green-beige pleochroism and defines the foliation together with amphibole. Subgrain formation in quartz occur together with undulatory extinction and triple points between the quartz grains. Calcite and plagioclase show lamellar twinning. A σ-type polycrystal sigmoid of quartz shows dextral movement. Also an amphibole δ-type porphyroclast shows dextral movement. Another shear sense indicator is dextral C´-type shear bands which partly show boudins. Bigger lenses in the thin-section show sinistral movement. The predominant dextral sense of shear gives a west-side up kinematics.

L07-1A-II (Amphibolite) The main minerals are amphibole, and epidote, with quartz, chlorite, plagioclase, opaque minerals, and calcite as accessory minerals. This thin-section contains more opaque minerals than L07-1A-I. Amphibole and chlorite defines the foliation, a slaty cleavage with a grain-preferred orientation. Subgrain formation is common in quartz, which also shows undulatory extinction and triple points. Lamellar twinning occurs in plagioclase, but the calcite in this thin-section show no twinning. A σ-type porphyroclast of quartz shows dextral movement. Dextral C´-type shear bands are common in this thin-section, and only a few sinistral shear bands are shown. Bigger lenses in the thin-section show sinistral movement.

L07-1B (Mica schist) The main minerals are biotite, and epidote, with quartz, plagioclase, chlorite, calcite, muscovite, opaque minerals, and zoisite as accessory minerals. Biotite defines the foliation. A fracture contains the vein-minerals, feldspar and muscovite. This sample contains relict porphyroblasts of epidote and feldspar. Subgrain formation, undulatory extinction, and triple points occur in quartz. Plagioclase show lamellar twinning.

001A (Volcaniclastic rock) The thin-section contains mainly feldspar, quartz, and plagioclase, with chlorite, muscovite, epidote, opaque minerals, and zircon as accessory minerals. The foliation is defined by chlorite as a grain preferred orientation. Some quartz grains show subgrain formation, while others show undulatory extinction, rounded embayments, bulging, and brittle fracturing. The feldspars show twinning, lamellar twinning for plagioclase and simple twinning for the other feldspars. The feldspar porphyroclasts show both brittle fracturing and undulatory extinction. About 50% of the chlorite grains in this sample have a purple colour, due to a different composition. Well preserved epidote occurs in a fracture that runs across the thin-section. The sense of shear is dextral, indicated by foliation deflection of chlorite, mineral fishes of feldspar and opaque minerals, and a fragmented C/S fabric.

017-A (Volcaniclastic rock) The thin-section contains quartz, feldspar, and plagioclase as main minerals, and muscovite, chlorite, and opaque minerals as accessory minerals. Muscovite and chlorite has a preferred orientation which defines the foliation. The quartz grains show brittle fracturing, undulose extinction, bulging, triple points, rounded embayments, and subgrain formation. Some feldspar porphyroclasts show subgrain formation, and brittle fracturing, while plagioclase shows lamellar twinning. The thin-section also shows sericite formation of feldspar. This is a sample with both sinistral and dextral σ-type porphyroclasts, but only dextral C´-type shear bands. It also contains primary phenocrysts.

017-B (Volcaniclastic rock) The thin-section contains mainly quartz and feldspar, with plagioclase, muscovite, opaque minerals, and chlorite as accessory minerals. The foliation is defined by chlorite and muscovite. The quartz porphyroclasts show brittle fracturing, embayments, subgrain formation, and undulose extinction. This sample shows no twinning of the

10

feldspars. Several σ-type porphyroclasts are present in this thin-section, which show sinistral movement. Also sinistral C´-type shear bands are present. The shear sense indicators give east side up kinematics.

026-C (Volcaniclastic rock) The thin-section contains quartz and feldspar as the main components, and plagioclase, chlorite, pyroxene, and opaque minerals as accessory minerals. The lineation is defined by chlorite. Brittle fracturing, undulatory extinction, subgrain formation, embayments, and bulging are common for quartz. The feldspars show brittle fracturing and subgrain formation, while the plagioclase shows lamellar twinning.

036-I (Volcaniclastic rock) Quartz and feldspar are the main minerals, while chlorite, plagioclase, biotite, muscovite, Fe-oxide, and a few epidote grains are accessory minerals. A strong foliation is defined by chlorite and biotite. The quartz porphyroclasts show brittle fracturing, undulatory extinction, subgrain formation and embayments. The feldspars show subgrain formation and brittle fracturing. Twinning occurs as lamellar twinning for plagioclase and simple twinning for other feldspars. This thin-section contains frequent kinematic indicators which all show a dextral movement by foliation deflection, σ- type feldspar and quartz porphyroclasts, and mineral fishes of quartz and feldspar. The dextral sense of shear gives east side up kinematics.

036-II (Volcaniclastic rock) The thin-section contains quartz and feldspar as main minerals, with biotite, muscovite, chlorite, and Fe-oxide as accessory minerals. Mica defines a strong foliation. Brittle fracturing, undulatory extinction, subgrain formation, bulging, and embayments are common features in quartz. The feldspar shows brittle fracturing and subgrain formation. Twinning occurs as simple twinning in feldspar. Frequent kinematic indicators occur, which show a dextral movement by foliation deflection, σ-type porphyroclasts of quartz and feldspar, and C-type shear bands. The dextral sense of shear gives east side up kinematics.

038-A (Volcaniclastic rock) Quartz and feldspar are the main minerals in this thin-section, while plagioclase, opaque minerals, chlorite, and zircon are accessory minerals. Chlorite defines the foliation. A cluster of about 20 zircons is present in this thin-section.

The quartz porphyroclasts show brittle fracturing, undulatory extinction, bulging, and embayments. Subgrain formation and brittle fracturing are common features in feldspar porphyroclasts and plagioclase shows lamellar twinning. A few kinematic indicators show dextral movement by foliation deflection and mineral fishes. The dextral sense of shear gives east side up kinematics.

052 (Granitoid) The thin-section contains quartz and feldspar as main minerals, and biotite, plagioclase, microcline, chlorite, epidote, and opaque minerals as accessory minerals. A weak lineation is defined by biotite. Quartz in this sample shows brittle fracturing, undulatory extinction, subgrain formation, bulging, and triple points. Brittle fracturing, subgrain formation, and undulatory extinction are also present in feldspar. Twinning occurs by simple twinning of feldspar and lamellar twinning of plagioclase and microcline. This thin-section shows sericite formation of plagioclase.

075 (Granitoid) The thin-section contains quartz and feldspar as main minerals, and biotite, chlorite, muscovite, calcite, opaque minerals, fluorite, pyroxene, and small epidote grains as accessory minerals. A more fine-grained Granitoid than sample 052 and a stronger foliation defined by chlorite. Brittle fracturing, undulatory extinction, subgrain formation, bulging, and triple points are deformation mechanisms in quartz. Feldspar shows brittle fracturing, and simple twinning, while calcite shows lamellar twinning. The muscovite/epidote show nice and well preserved crystals.

076 (Metabasalt) The main minerals are amphibole, biotite, and feldspar, with chlorite epidote, quartz, opaque minerals, and zoisite as accessory minerals. The foliation is defined by chlorite and amphibole by a grain-preferred orientation. Subgrain formation and undulatory extinction are deformation mechanisms in the quartz grains.

11

Feldspar and amphibole show brittle fractures. Shear sense indicators are dextral foliation deflection and dextral δ-type and σ-type porphyroclasts of feldspar. The dextral sense of shear gives an east-side up kinematics.

077-B (Mylonite) The main minerals in this thin-section are quartz and feldspar, with plagioclase, chlorite, muscovite, epidote, titanite, and Fe-oxide (hematite) as accessory minerals. The foliation is defined by chlorite. Deformation mechanisms in quartz are brittle fracturing, undulatory extinction, and subgrain formation. In feldspar the deformation mechanisms are brittle fracturing, and subgrain formation. C´-type shear bands, σ-type porphyroclasts of feldspar, and domino-type fragmented clasts of epidote shows dextral movement. The dextral sense of shear gives east side up kinematics.

091-A (Volcanic fragment) The thin-section contains quartz and feldspar as main minerals, with plagioclase, microcline, chlorite (purple), opaque minerals, and a few grains of epidote as accessory minerals. Quartz and feldspar defines the foliation by a grain-preferred orientation. Deformation mechanisms in quartz are brittle fracturing, undulatory extinction, subgrain formation and bulging. The feldspar shows subgrain formation and simple twinning, while plagioclase shows lamellar twinning.

091-B (Diorite/Gabbro) This thin-section contains mainly amphibole, with calcite, chlorite, epidote, quartz, and opaque minerals as accessory minerals. The foliation is defined by amphibole as a grain-preferred orientation. Deformation mechanisms in amphibole are brittle fracturing and simple twinning, while the calcite grains are deformed by lamellar twinning. σ-type porphyroclasts of amphibole show dextral movement, and dextral boudinaged amphiboles also occur.

092-A (Volcaniclastic rock) This thin-section contains quartz, plagioclase, and feldspar as main porphyroclasts and quartz and feldspar in the matrix, with chlorite and muscovite as accessory minerals. Quartz and feldspar defines the foliation by a grain-shape preferred orientation. Deformation mechanisms in feldspar are brittle fracturing and lamellar twinning of plagioclase. In quartz the deformation mechanisms are brittle fracturing, undulatory extinction, subgrain formation, bulging, and triple points.

092-B (Ultramafite) This thin-section contains mainly amphibole and feldspar, with epidote, chlorite, quartz, and muscovite as accessory minerals. A grain preferred orientation of amphibole defines the foliation. Amphibole shows deformation by brittle fracturing, undulatory extinction and simple twinning. Indications of both dextral and sinistral movement occur, by σ-type porphyroclasts of amphibole, boudinaged feldspar, and C´-type shear bands. But slightly more indicators for dextral movement exist, which gives an east-side up movement.

093 (Granitoid) This thin-section contains quartz, feldspar, and biotite as main minerals, and chlorite, plagioclase, microcline, muscovite, and epidote as accessory minerals. The lineation is defined by chlorite and biotite. Plagioclase and microcline have lamellar twins, while quartz shows brittle fracturing, undulatory extinction, subgrain formation, and bulging. Also symplectite is present in this sample.

1

Appendix 2 Master thesis by Michaela Åberg.

UPPSALA UNIVERSITY

Taking the Temperature &

Pressure on Dannemora.

Thesis

Michaela Åberg

.2009.

Uppsala University Taking the Temperature & Pressure on Dannemora.

2

Abstract

Dannemora ore deposit is hosted by Palaeoproterozoic, Svecofennian, marble and consists of 25

bodies of skarn iron ore in limestone with an alternating high and low content of manganese. The

deposit also contains a few sulphide mineralizations, which were investigated by microscopy and

electron microprobe analyses to see if it is possible to use sphalerite as geobarometer and arsenopyrite

as geothermometer. Arsenopyrite gave a temperature of 375±105o

C, however zoned arsenopyrite

crystals showed variable negative temperatures (low in As). The pressure for sphalerite was estimated

in two ways, by a plot figure and by an equation by Hutchison & Scott (1981). The first calculation

gave a pressure estimate of 3.7±0.4 kb, and the second a pressure of 2.2 to 4.4 kb. The sphalerite is

apparently sensitive to high manganese contents (>1.0 wt %) in one sample, resulting in an unrealistic

pressure of 11.3 kb. Besides minor discrepancies, the obtained data of temperature and pressure

correspond well with the metamorphic grade of the area of greenschist to lower amphibolite facies.

Sammanfattning

Dannemora malmstråk ligger i Palaeoproerozoiska, Svecofenniska, metavulkaniska bergarter och

består av 25 kroppar av skarnjärnmalm i kalksten med ett omväxlande högt och lågt innehåll av

mangan. Fyndigheten innehåller även några sulfidmineraliseringar, vilka undersökts genom

mikroskopering och elektron mikrosond analys för att ta reda på om det är möjligt att använda

zinkblände som geobarometer och arsenikkis som geotermometer. Arsenikkisen ger en temperatur på

375±105oC, dock indikerar zonerad arsenikkis variabla negativa temperaturer (låg As-halt).

Zinkbländebarometrin har använts dels genom en plottad figur, dels genom en ekvation av Hutchison

& Scott (1981). Den första metoden gav ett ungefärligt tryck på 3.7±0.4 kb och den andra 2.2 till 4.4

kb. Zinkbländet är tydligen känsligt för mangan (>1.0 wt %), vilket i ett prov resulterade i ett

imaginärt tryck på 11.3 kb. Förutom mindre avvikelser, motsvaras temperatur och tryck data den

metamorfa graden i området av grönskiffer till lägre amfibolit facies.

Uppsala University Taking the Temperature & Pressure on Dannemora.

3

Table of Contents Abstract ................................................................................................................................................... 2

Sammanfattning....................................................................................................................................... 2

Table of Contents .................................................................................................................................... 3

1. Introduction ..................................................................................................................................... 4

1.1 The purpose of this work ........................................................................................................... 4

2. Background ......................................................................................................................................... 5

2.1 Geology of Bergslagen .............................................................................................................. 5

2.2 Geology of Dannemora ............................................................................................................. 5

3. Chemistry ............................................................................................................................................ 6

3.1 (Zn, Fe)S – Sphalerite................................................................................................................ 6

3.2 FeAsS – Arsenopyrite. ............................................................................................................... 6

4. Methods ............................................................................................................................................... 6

4.1 Sample preparations .................................................................................................................. 6

4.2 Microscopy ................................................................................................................................ 7

4.3 Electron microprobe analysis .................................................................................................... 7

4.4 Sphalerite geobarometry ........................................................................................................... 8

4.5 Arsenopyrite geothermometry ................................................................................................... 8

4.6 Calculations ............................................................................................................................... 9

5. Results ............................................................................................................................................... 10

5.1 Microscopy .............................................................................................................................. 10

5.2 Electron microprobe analysis .................................................................................................. 14

6. Discussion ......................................................................................................................................... 23

7. Conclusions ....................................................................................................................................... 26

8. Further studies ................................................................................................................................... 26

9. Acknowledgements ........................................................................................................................... 27

10. References ....................................................................................................................................... 27

11. Appendices ...................................................................................................................................... 29

11.1 Tables recalculated from the EMPA result. .......................................................................... 29

11.1.1 Recalculated sphalerite analyses where Zn+S+Fe=100 at.% ......................................... 29

11.1.2 Table of results from calculating equation 3. ................................................................. 29

11.2 Electron Microprobe Analyse results. ................................................................................... 30

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1. Introduction

Dannemora is situated in the eastern part of central Sweden, about 45 km NNE of Uppsala. The

Dannemora ore deposit consists of about 25 bodies of skarn iron ore and limestone with a partly Mn-

rich and partly Mn-poor content (Lager 2001). The deposit also contains a small number of sulphide

mineralizations. The deposit is hosted by Palaeoproterozoic, Svecofennian, metavolcanic rocks

(hosted in marble), i.e. approx. 1.9Ga (Lager 2001).

1.1 The purpose of this work

Main question:

1. Is it possible to use sphalerite and arsenopyrite from Dannemora, to perform

geothermometry and geobarometry?

Other questions that have come up during the project are:

2. Must sphalerite and arsenopyrite be buffered by pyrite and pyrrhotite, or how will

buffering or non-buffering affect the results?

3. Does zoning in arsenopyrite influence the result, and if so in what way?

4. How will other elements affect the result?

The samples are from two drill cores from the Södra Fältet in Dannemora, with coordinates: N

6677650/E 1613510, N 6677612/E 1613585 in RT90 coordinate system.

Figure 1) Overview of Dannemora mining site. Figure 2) Air photo of Dannemora mining site.

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2. Background

2.1 Geology of Bergslagen

Bergslagen is interpreted as an extensional, active continental margin magmatic region, probably a

back- arc. It evolved through stages of intense magmatism, thermal doming, and crustal extension,

followed by waning extension, waning volcanism, and thermal subsidence, reversal from extension to

compressional deformation, regional metamorphism, and structural inversion (Allen et al 1996). The

dominating rocks in Bergslagen are granitoids. Most of the ore deposits occur in hydrothermally

altered metavolcanic rocks and associated metalimestones and skarns. Generally the ore deposits

formed during the regional waning volcanic stage and occur in medial to distal facies associations that

comprise rhyolitic ash-siltstone, limestone, and vitric crystal sandstone and breccia (Allen et al 1996).

During the Svecokarelian orogeny, the rocks of Bergslagen were deformed and metamorphosed at

different grades of regional pressure metamorphism. A number of well preserved areas can be found in

western Bergslagen. As a result of the generally stronger regional metamorphism, this type is rare in

the eastern, coastal areas in Bergslagen (Lager 2001).

2.2 Geology of Dannemora

The Dannemora area probably belongs to the uppermost part of a volcanic sequence, which

characterizes the whole of the metalliferrous Bergslagen areas in southern, central Sweden (Lager

2001).

The Dannemora ore deposit is in general defined as a relatively mafic skarn ore (Geijer & Magnusson

1944), with varying manganese content. The Mn- rich skarn ore shows manganese contents of up to 25

% (Lager 2001). The ore is associated with a dolomitic limestone which is surrounded by a

metavolcanc rock metamorphosed in greenschist facies (Lager 2001, Peter Dahlin pers.com 2009).

The skarn rocks associated with limestone and dolomite are sporadically associated with iron ores.

Typical key minerals of the carbonaceous rocks are; diopside, epidote, garnet (of different

compositions, depending on Mn-content), actinolite, olivine, serpentine, spinel, brucite, wollastonite

and vesuvianite. Rarer minerals include knebelite (Mn-olivine) and dannemorite (Mn-commingtonite,

also called Mn-grunerit (webmineral.com 09.04.24)) (Stålhös 1991). The skarn ores have varying iron

content, between 30 and 50 %, rarely 65 %. The iron ore is normally massive, and strata- bound to the

parts of the dolomitic limestone which contain stromatolite-resembling structures and pseudomorphs

after evaporates, which the iron ore has replaced partly or completely (like impregnations in the

carbonaceous rocks) (Lager 2001, Stålhös 1991). The iron ores are made up of aggregates of several

minerals, but the main component is magnetite, characterized by a very low content of phosphorus

(0.001 – 0.007 % P). Locally sulphide mineralizations are common, usually with sphalerite, iron

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sulphides, chalcopyrite, galena and arsenopyrite. The sulphur content of the oxide ores is less than 1

wt.% (Lager 2001, Stålhös 1991).

3. Chemistry

3.1 (Zn, Fe)S – Sphalerite.

Besides iron, mercury (Hg), cadmium (Cd) and manganese (Mn), in amounts of up to 1 wt%, are

almost always present in sphalerite. Pure sphalerite is white, but with increasing Fe, the mineral

becomes progressively yellowish, then brownish – blackish with an increasing metallic lustre. Under

reflected light sphalerite gets a higher reflectivity and becomes brighter, like a “true” ore mineral

(Amcoff 2001). The composition of sphalerite does not only depend on chemical environment, but

also on the physical conditions in terms of pressure and temperature. The FeS content in sphalerite

does not change much as temperature increases, but it decreases considerably as pressure increases.

The pressure effect: the molar volume of (Zn, Fe)S of a given composition is larger than the bulk

molar volume of FeS (in pyrrhotite) + (Zn, Fe)S (Fe-poorer), with identical bulk chemistry. So as

pressure is raised FeS tends to “creep out” from (Zn, Fe)S and become included in adjacent pyrrhotite

(Fe1-XS). Sphalerite in metamorphosed rocks is often found in phase assemblages with pyrite (FeS2)

and pyrrhotite (Fe1-XS) (Ribbe 1973).

3.2 FeAsS – Arsenopyrite.

Arsenopyrite is one of the most refractory of the base sulphides. Besides, it is a potentially helpful

geochemical tool for deciphering conditions of ore formation because it shows a variability in As/S

ratio (Kretschmar & Scott 1976). Arsenopyrite is associated with the arsenic group of elements, with

arsenic (As), antimony (Sb) and bismuth (Bi). In nature these elements often occur in minor amounts

in sulphosalts, commonly associated with the galena-rich parts of massive sulphide ores. However,

arsenic is most often found in arsenopyrite (FeAsS) which can be derived from the orthorhombic

marcasite group, MeS2. It is the most prominent arsenic source, and constitutes a major environmental

problem (Amcoff 2001).

4. Methods

4.1 Sample preparations

Twenty drill core samples Södra Fältet of Dannemora were sawed to a size of 1-2*3 cm, to prepare

them for microscopy and microprobe analysis.

The samples were first polished with a silicon carbide powder then with diamond powder. The

polishing process is done in stages with decreasing polish powder size. Starting with silicon carbide of

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size 80 µm, down to 15 µm and then 12 µm. The polishing was done on a glass plate by hand.

Polishing with diamond powder was done in three stages (different powder size), first 6 µm, then 3 µm

and then 1 µm. This part of the polishing is made with a polishing machine with a rotating plate

covered with polishing fabric. The plate rotates anticlockwise and the sample is rotated clockwise by

hand. Also the sample is turned 90 degrees in even intervals.

4.2 Microscopy

The ore microscope is a basic instrument for petrographic examination of opaque minerals. A light

source above the sample allows examination by reflected light from a polished surface (Craig and

Vaughan 1994).

In this study two microscopes were used, a Nikon Eclipse E 600 POL and an Olympus BX60. The first

one is equipped with a camera connected to a computer. A data program (NIS- Elements, F 2.20)

processes the pictures.

4.3 Electron microprobe analysis

Electron microprobe analysis (EMPA) is one of the most used

instruments for determining the chemical composition of

minerals (Nesse 2000). It is an analytical technique used to

study the composition of small areas of samples (~2µm

diameter) (Web site of the University of Minnesota Regents,

Microprobe Laboratory 2009). The sample is bombarded with a

beam of accelerated electrons. The beam is concentrated on the

surface of the sample through a series of electromagnetic

lenses. The energetic electrons create characteristic X-rays

within a small volume of the sample (Web site of the

University of Minnesota Regents, Microprobe Laboratory

2009). The method is also useful to detect variations within

a mineral grain and inclusions of other minerals can be

avoided (Nesse 2000).

The characteristic X-rays are detected at specific wavelengths, and their intensities are measured to

find out the concentrations. Today all elements except hydrogen, helium and lithium can be detected

by their unique wave lengths (Web site of the University of Minnesota Regents, Microprobe

Laboratory 2009).

The electron microprobe must be calibrated according to the minerals of interest. In this study: sulphur

(S), zinc (Zn), iron (Fe), arsenic (As), lead (Pb), copper (Cu), antimony (Sb), bismuth (Bi), cobalt

Figure 3) Schematic diagram of an electron microprobe.

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(Co), nickel (Ni), manganese (Mn), mercury (Hg), cadmium (Cd) and silver (Ag) were analysed. The

samples were analysed by a Cameca 50X microprobe, using a 20 kv accelerating voltage, and a

current of 15 nA. Before a sample was analysed it was coated with carbon, to provide good

conductivity.

4.4 Sphalerite geobarometry

Already Kullerud (1953) recognized the potential of the FeS content of sphalerite as an indicator of

conditions of sulphide formation (Hutcheon 1978). The idea and theory behind sphalerite

geobarometry was later developed by Paul B. Jr. Barton and P. Toulmin in 1966. They suggested that

the iron content of sphalerite depends on pressure in the range of conditions of geological interest

(Martín and Soler I Gil 2004). Further development was done by Scott and Barns (1971) and Scott

(1973) as seen in Scott (1976).

In short, the FeS content of sphalerite is a function of pressure (P), temperature (T) and FeS activity

(aFeS). The FeS activity also depends on composition; the sphalerite has to be buffered by both iron

sulphide phases (Scott 1976). Pyrite + pyrrhotite provide the needed buffering of aFeS where the

composition of coexisting sphalerite is approximately independent of temperature over a large interval

(254 – 550oC). This interval was investigated by Barton and Toulmin (1966) and by Scott & Barnes

(1971) and it is strongly dependent on the confining pressure (Hutchison and Scott 1980; Koh et al,

1992).

Contaminants such as Co, Ni, Mn, Cu, Cd and Hg may affect the sphalerite geobarometer if they enter

into sphalerite or pyrrhotite in significant amounts and change the partial molar volume of FeS in

sphalerite and the activity of FeS of the system. The low amounts of cobalt and nickel in most natural

pyrrhotites and solid solutions of cadmium and manganese in sphalerite have been shown to have no

considerable effect on the pressure dependence of FeS in sphalerite (Hutchison and Scott, 1981). Of

the remaining elements only copper is problematical (Hutchison and Scott, 1981). Most natural

sphalerites contain less than 0.5 wt. percent copper in solid solution, even if sphalerites frequently host

small chalcopyrite grains (often called chalcopyrite disease). A question that comes up is whether the

small chalcopyrite grains have an effect on the sphalerite + pyrrhotite + pyrite phase relations. The

role of copper in naturally occurring sphalerite + pyrite + pyrrhotite metamorphic equilibria is not

fully understood, thus sphalerite which contains inclusions of chalcopyrite should be avoided for

geobarometric purposes (Hutchison and Scott, 1981).

4.5 Arsenopyrite geothermometry

Arsenopyrite is one of a few sulphides, besides sphalerite that is rather resistant to chemical change

and exhibits noticeable solid- solution sensitivity to pressure or temperature (Sharp, Essene & Kelly

1985). Thus, arsenopyrite shows a wide range in As/S ratios which makes it a potentially useful

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geochemical tool for deciphering conditions of its formation (Kretschmar & Scott 1976).

Stoichiometric arsenopyrite has the formula FeAsS. In the present case arsenopyrite is better

represented by Fe(AsXS2-X)2 (see results below).

The essence of arsenopyrite geothermometry is to determine the composition of arsenopyrite as a

function of temperature in assemblages representing different buffer conditions (Kretschmar & Scott,

1976).

When sphalerite and arsenopyrite are buffered with respect to sulphur (pyrite + pyrrhotite), the content

of FeS in ZnS depends on the confining pressure, while the As/S ratio of arsenopyrite is primarily a

function of the temperature. The composition of sphalerite and arsenopyrite are both very sensitive to

the fugacity of S2 (fS2) (Berglund & Ekström 1980).

4.6 Calculations

The result from the microprobe analysis where recalculated by neglecting the minor elements,

assuming that they have no significant impact on the result. Thus, in the case of sphalerite zinc +

sulphur + iron were recalculated to 100%. Also, for arsenopyrite arsenic + sulphur + iron were

likewise recalculated to 100%.

Thus, calculating the content of FeS in sphalerite:

Equation 1

In a similar way, the content of arsenic in arsenopyrite can be calculated:

Equation 2

Equation 3 (below), by Hutchison & Scott (1981), can be used to calculate the pressure for sphalerite.

It describes the pressure dependence of sphalerite in equilibrium with pyrrhotite and pyrite.

Equation 3

Based on many analyses by different authors, the equation has a correlation coefficient of 0.993 and a

standard error of ±0.30 kb (Hutchison and Scott 1981) (see table in appendices, 11.1.3).

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5. Results

5.1 Microscopy

After many hours of polishing, eight samples were chosen for a more thorough examination by the

microscope. In table 1 the minerals found by microscopy are presented.

Sample No. Detected ore minerals:

3012 – 124.25 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena, and some chalcopyrite.

3012 – 124.30 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena, and chalcopyrite.

3012 – 130.30 Sphalerite, pyrrhotite, arsenopyrite, magnetite, pyrite, and chalcopyrite.

3012 – 130.60 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena, pyrite and chalcopyrite.

3015 – 100.60 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena and pyrite.

3015 – 100.70 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena, pyrite and some sulphosalt.

3015 – 104.25 Sphalerite, pyrrhotite, arsenopyrite, magnetite, pyrite and some chalcopyrite.

3015 – 106.10 Sphalerite, pyrrhotite, arsenopyrite, magnetite, galena and chalcopyrite.

Table 1) Observed ore minerals in the polished samples.

In all samples, sphalerite, pyrrhotite, arsenopyrite and magnetite were found. Figures 4 – 9 below

show selected pictures of polished sections. The pictures show some of the most common minerals

and textural relations found in the samples.

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Figure 4) Sample 3012-124.25: Polished section with a triangular aggregate of pyrrhotite (light

beige/yellowish) surrounding sphalerite (light gray) with some galena (bright white). Magnification 100

times.

Figure 5) Sample 3012-124.30: Polished section with pyrrhotite (light brown/beige) with sphalerite (in the

middle, grey), chalcopyrite (yellow) and some galena (light grey/white). Magnification 100 times.

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Figure 6) Sample 3015-100.60: Polished section with sphalerite (grey) with distinct red internal reflections

and arsenopyrite (blue & orange). Magnification 100 times.

Figure 7) Sample 3015-100.70: Polished section with galena (light gray/white) in sphalerite (gray). The

galena contains some sulphosalt in light gray (see orange arrow). Magnification 200 times.

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Figure 8) Sample 3015-100.70: Polished section with a pyrite crystal (light yellow) in sphalerite (grey),

locally around pyrite small patches of galena (light grey/white). Magnification 100 times.

Figure 9) Sample 3015-104.25: Polished section with pyrrhotite (beige/light brown) and sphalerite (gray)

in pyrite (white/light yellow). Magnification 200 times.

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5.2 Electron microprobe analysis

After examination of the samples under reflected light, five samples were selected for more thorough

examination by electron microprobe analysis. The result from this investigation are complied below in

a number of Figures and Tables:

The compositions of all sphalerites (fifteen investigated spots) are shown in Tables 2-3 and Figure 10.

The compositions of arsenopyrite are shown in Tables 4-5 and the variations in As/S ratio in Figure

11. Moreover, the compositional zoning in arsenopyrite is shown in a series of BSE images (Figs 12-

16) and a series of traverses across the crystals (Figs 17-22), while bulk compositions are shown in Fig

23 and Table 6. Also, based on the analyses, a diagram showing composition versus temperature for

arsenopyrite was constructed (Fig 24), while in a temperature versus composition (mole % FeS)

diagram for sphalerite, the compositions of the analysed sphalerites are shown relative Scotts (1973)

empirical curves.

Sample No.,

Point No.

Fe in

sphalerite (in

mole %),

original

Fe in sphalerite

(in mole %)S,

recalculated

(eq.1)

Mn in

sphalerite

(at.%)

Comments

3012–124.25, 1 13,03 14,98 0,17 Sph in contact with po

3012–124.25, 2 14,19 16,53 0,22 Sph in contact with po

3012–124.25, 3 12,25 13,96 0,18 Sph in contact with po

3012–130.30, 1 16,87 20,29 0,15 Sph in py

3012–130.30, 2 14,49 16,95 0,11 Sph in py and in contact with po

3012–130.30, 6 12,24 13,95 0,11 Sph in po

3012–130.30, 15 12,98 14,92 0,13 Sph in contact with py and po

3012–130.30, 18 12,56 14,37 0,12 Sph in contact with po

3015–100.60, 12 8,78 9,63 1,68 Sph with high concentration Mn

3015–100.60, 18 8,77 9,61 1,66 Sph with high concentration Mn

3015–100.60, 20 7,878 8,55 1,72 Sph with high concentration Mn

3015–104.25, 1 13,39 15,46 0,63 Sph in contact with po

3015–104.25, 17 14,73 17,28 0,57 Sph in py

3015–104.25, 30 16,57 19,87 0,70 Sph in contact with py and po

3015–104.25, 37 14,93 17,54 0,78 Sph in contact with po (close to py)

Table 2) Iron content in sphalerite of all the analysed samples and comments on the analyzed spot. (Sph=

sphalerite, py=pyrite and po=pyrrhotite).

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Sample No. Mean Fe content in sphalerite (in

mole%) EMPA

Mean Fe content in sphalerite (in

mole%). Equation 1

3012-124.25 13,08 15,16

3012-130.30 13,76 16,09

3015-100.60 8,16 9,26

3015-104.25 15,14 17,54

Table 3) Average iron content in sphalerite.

Figure 10) Fe-Zn-S ternary plot for the analysed sphalerites (n=15). The plot shows a mean of around 5%

iron, 45% zinc and 50% sulphur.

Or

An

Graf:

Ab

S

Zn

Fe-Zn-S

Fe

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Sample No.,

Point No.

S in FeAsS

(in at.%)

Fe in FeAsS

(in at.%)

As in FeAsS

(in at.%)

Comments

3012-124.25, 8 36,41 33,34 30,25

3012-124.25, 9 36,66 31,85 31,50

3012-124.25,10 36,72 30,80 32,48

3012-124.25, 11 36,50 30,89 32,61

3012-130.30, 7 40,43 33,80 25,768 Darker in colour, a lower content of As

3012-130.30, 8 35,37 34,02 30,61 Lighter in colour, a higher content of As

3012-130.30, 13 35,68 34,15 30,17 Asp in py, in contact with po

3012-130.30, 16 36,22 33,90 29,87 Zoned, darker zone analysed

3012-130.30, 17 34,37 33,95 31,31 Zoned, lighter zone analysed

3015-100.60, 2 30,24 30,24 36,20 Zoned asp crystal. See Figure 12

3015-100.60, 3 34,47 33,51 32,02 Zoned asp crystal. See Figure 12

3015-100.60, 4 33,70 33,95 32,35 Zoned asp crystal. See Figure 12

3015-100.60, 5 43,74 33,00 23,26 Zoned asp crystal. See Figure 12

3015-100.60, 6 35,68 33,94 30,38 Zoned asp crystal. See Figure 12

3015-100.60, 7 35,06 33,21 31,73 Zoned asp crystal. See Figure12

3015-100.60, 8 31,38 33,26 35,36 Zoned asp crystal. See Figure 13

3015-100.60, 9 31,86 33,94 34,20 Zoned asp crystal. See Figure 13

3015-100.60, 10 31,27 34,22 34,52 Zoned asp crystal. See Figure 13

3015-100.60, 11 35,91 34,22 29,87 Zoned asp crystal. See Figure 13

3015-104.25, 4 35,76 33,92 30,32 In contact with both py and po (triple point)

3015-104.25, 6 35,53 33,61 30,86 Buffered with py and po

3015-104.25, 11 35,32 32,95 31,73 Triple point, in contact with po and py

3015-104.25, 21 34,51 33,97 31,52 Triple point, in contact with py and po

3015-104.25, 22 34,44 33,86 31,70 Triple point, in contact with py and po

3015-104.25, 33 35,87 33,36 30,77 Triple point, in contact with po and py

3015-104.25, 44 34,44 32,81 32,74 Triple point, in contact with py and po

Table 4) Results of the analyzed arsenopyrite samples and comments on the analyzed spot. (Asp=

arsenopyrite, po=pyrrhotite and py= pyrite).

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Sample No. Mean As content (in at.%)

3012-124.25 31,71

3012-130.30 29,53

3015-100.60 31,97

3015-104.25 31,37

Mean sum: 31,14

Table 5) Average at. % arsenic content in arsenopyrite.

Figure 11) Scatter plot As/S for all the analysed points in arsenopyrite (n=26).

Figure 12) Back scatter picture showing a zoned

arsenopyrite crystal. p2 – p7 show where the

analyses were done.

Figure 13) Back scatter picture showing a zoned

arsenopyrite crystal. p8 –p11 show where the

analyses were done.

20

25

30

35

40

25 30 35 40 45 50

As,

at%

S, at%

As/S

3012-124.25

3012-130.30

3015-100.60

3015-104.25

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Figure 14) Back scatter picture showing a zoned

arsenopyrite crystal. Traverse line indicated.

Figure 15) Back scatter picture showing a zoned

arsenopyrite. The traverse from the middle to the rim

is indicated.

Figure 16) Back scatter picture showing a zoned

arsenopyrite. Traverse line from the light area towards

the darker area is indicated.

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Scatter plots of the traverses.

Figure 17) Scatter plot for traverse 1, As/S (at.%), n = 25.

Figure 18) Travers 2

Figure 19) Scatter plot for Travers 2, As/S (at.%), n=50.

25

30

35

40

25 27 29 31 33 35 37 39

As,

at%

S, at%

As/S, travers 1

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

at%

As and S in FeAsS, travers 1

As

S

25

30

35

40

25 27 29 31 33 35 37 39

As,

at%

S, at%

As/S, travers 2

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Figure 20) Travers 2 FeAsS, n=50.

Figure 21) Scatter plot for Travers 3, As/S (at.%), n=50.

Figure 22) Travers 3 FeAsS, n=50.

25

27

29

31

33

35

37

39

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

At

%As and S in FeAsS, travers 2

As

S

25

30

35

40

25 27 29 31 33 35 37 39

As,

at%

S, at%

As/S, travers 3

25

27

29

31

33

35

37

39

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

At

%

As and S in FeAsS, travers 3

As

S

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As mentioned earlier arsenopyrite is better represented by Fe(AsXS2-X)2. So in table 6 the results of the

calculated formula of arsenopyrite is presented.

Sample No. Composition

3012-124.25 Fe0.95As0.95S1.1 (n= 4)

3012-130.30 Fe1.02As0.98S1.02 (n= 5)

3015-100.60 FeAs0.96S1.04 (n= 10)

3015-104.25 FeAs0,94S1.06 (n= 7)

Table 6) Composition of arsenopyrite.

Or

An

Graf:

Ab

S

As

Fe-As-S

Fe

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Figure 23) Fe-As-S ternary plot for all samples, n=26. The plot shows an average of around 33% iron,

approximately 30% arsenic and 35% sulphur.

Figure 24) Temperature and atomic percent As in FeAsS, n = 26. The temperature scale in the figure is

extrapolated from Sundblad et.al, 1984. Who analysed samples buffered with pyrite + pyrrhotite.

Besides the low atomic percent values the temperature clusters between 280 – 470 Co.

Figure 25) Temperature and pressure diagram for FeS in sphalerite. Pressures are in bars. The isobars in

the figure is taken from Scott (1973, p. 469). Where spalerite is buffered by pyrite + pyrrhotite.

Besides the green dots the pressure ranges from just over 1 bar up to around 5000 bars.

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Besides the major phases, some minor minerals were analysed. Microprobe analyses of sample 3015-

100.70 indicate tetrahedrite ((Cu,Fe,Ag,Zn)12Sb4S13), and two other sulfosalts; pyragyrite (Ag3SbS3)

and the more unusual sulfosalt diaphorite (Pb2Sb3Ag3S8).

6. Discussion

Buffered assemblages; arsenopyrite + pyrite +pyrrhotite or sphalerite + pyrite + pyrrhotite are not

always present in the investigated samples. However pyrite + pyrrhotite can be seen within the same

polished section in most of the cases. Microprobe analysis shows some differences between different

grains. In fact, the maximum FeS content is found in a spot with sphalerite + pyrite (lacking

pyrrhotite). This is quite opposite of what can be expected from equilibrium reasoning, but can

probably be explained by a disappearance of the reactive pyrrhotite during retrograde metamorphism,

while the inert phases, sphalerite and pyrite, remained unaffected. Also for sphalerite in intimate

contact with both pyrite + pyrrhotite the FeS content varies, indicating poor equilibrium. As mentioned

above, the reactive pyrrhotite probably retrogrades down to low temperature, while the other phases

“freeze” at higher temperatures. This could show up in the structure of pyrrhotite, where a sulphur-rich

variety should be equivalent with monoclinic pyrrhotite (Fe 0.877S), while sulphur-poor compositions

(Fe0.936–0.900S) are equivalent with hexagonal pyrrhotite (Clark 1965). However, X-ray diffraction

analysis has been outside the scope of the present study.

Figure 26) Microscope picture showing galena with sulfosalts; green arrows = tetrahedrite, red arrow = pyragyrite. Magnification 200 times.

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The result from the microprobe analysis of arsenopyrite shows that the content of iron is rather

constant while As/S varies. This is obvious in the zoned crystals, where the darker parts are less As-

rich than the lighter parts (seen in BSE-images, where lighter mean atomic weight are represented by a

lighter colour).

The scale in fig.24, extrapolated from Sundblad et.al 1984, indicates negative temperatures for the As-

poorest arsenopyrites; which of course is impossible. The crystal was zoned, and the low As content

does not represent the entire crystal. Most points cluster around 280 – 470oC, which correspond to

greenschist to lower amphibolite facies (see Figure 28). Despite the zoning arsenopyrite compositions

frequently indicate initial formation temperatures (Kretschmar & Scott 1976). They explain the zoning

to reflect local disequilibrium during growth.

Hutchison and Scott (1981) showed that cobalt and manganese have no significant effect on the

pressure dependence of FeS in sphalerite. However, in the present study the concentration of

manganese is high in one sample (sample 3015-100.60), with over 1,5 at% Mn (see Figure 27). The

corresponding reduction in FeS content resulted in an imaginary pressure of 11.3 kb (1130 MPa).

Figure 27) Manganese versus iron in sphalerite (n=15).

The other samples with a lower content of manganese in sphalerite cluster between pressures of 2.4 –

4.4 kb (240 – 440 MPa) (Equation 3). Even though sample 3015-104.25 shows a higher content of

manganese compared with 3012-124-25 and 3012-130.30, this does not show up in Fig 27. The higher

manganese content of these two samples can be explained by the fact that they originate from the same

drill core.

Both the calculated (equation 3) and the plotted values (Fig 25) fit nicely within greenschist to lower

amfibolite facies, as in the Dannemora area.

0

0,5

1

1,5

2

2 4 6 8 10

Mn

(at

%)

Fe (at%)

Mn/Fe in (Zn,Fe)S

3012-124.25

3012-130.30

3015-100.60

3015-104.25

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Figure 28) Metamorphic Facies. Marking of the result from this study, are marked by the stippled rectangle.

Hutchison and Scott (1981) also discussed the effect of copper on the sphalerite geobarometer and

noted that copper is a problematic element. However, in the present study the electron microprobe

analysis showed very low concentrations of copper in sphalerite.

Many studies on the sulphide minerals have been done in the laboratory; where the minerals are

produced in a controlled environment, with known temperatures and pressures. In this way it is

possible to see how the elements react with each other and how temperature and pressure affect the

system. Besides, it is common to use silicate paragenesis to determine metamorphic conditions (Lynch

& Mengel 1995), and from these conditions calibrate the arsenopyrite geothermometer. Thus, for the

natural paragenesis the pressure and temperature histories have previously been independently

established (Sharp, Essene & Kelly 1985).

Uppsala University Taking the Temperature & Pressure on Dannemora.

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7. Conclusions Q: Is it possible to use sphalerite and arsenopyrite from Dannemora, to perform geothermometry and

geoberometry? A: Yes, but reliability must be discussed. The structure of pyrrhotite should be

established. Additionally, the choice of EMPA standards can affect the results. However the results in

this study give temperatures between 280 – 470oC and pressures of 2.4 – 4.4 kb.

Q: Must sphalerite and arsenopyrite be buffered (coexisting with pyrite + pyrrhotite), or how will

buffering or non-buffering affect the results? A: The results from the sphalerite analysis suggest that

the FeS-content varies, more or less independently of whether the mineral is in contact with pyrite,

pyrrhotite or both. This suggests retrograde disequilibrium. The arsenopyrite gave a less clear result

then sphalerite.

Q: Does zoning in arsenopyrite influence the result, and if so in what way? A: Yes, zoning influences

the result greatly. Knowledge of this can prevent misleading results. This study recommends using the

mean value of a zoned crystal. However, the zoning can tell us something about the arsenopyrite

growth history.

Q: How do other elements affect the geothermobarometry? A: this study suggests that manganese is

the important “contaminating” element, as seen in a significant decrease in iron in sphalerite.

8. Further studies

It would be interesting to examine the structure of pyrrhotite using x-ray diffraction (XRD), to

conclude if it is monoclinic or hexagonal.

An extended investigation using more samples would be useful to see if buffering or non-buffering

will affect the result. Especially of extend the investigation on the effect of manganese on sphalerite. Is

it possible to see any effect of manganese in the microscope?

Can magnetite give a clue to the metamorphic path? How does magnetite affect the sulphides? What is

the relation between magnetite and the sulphides? This important question has also been outside the

scope of the present paper.

Uppsala University Taking the Temperature & Pressure on Dannemora.

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9. Acknowledgements

Big thanks to Dannemora Mineral AB, who provided me with samples from Södra Fältet in

Dannemora, and made this study possible. I like to thank my mentor Örjan Amcoff for all the help and

support. A special thanks to Peter Dahlin, for help, support and inspiration. Thanks to Hans Harrysson

for all the help with the electron microprobe analysis. I also want to thank my roommates for all the

great discussions we have had and of course all the support.

10. References

Allen, R., Lundström, I., Ripa, M., Simeonov, A. and Christofferson, H. (1996) Facies Analysis of a 1.9 Ga,

Continental Margin, Back-Arc, Felsic Caldera Province with Diverse Zn-Pb-Ag-(Cu-Au) Sulfide and Fe Oxide

Deposits, Bergslagen Region, Sweden. Economic Geology, vol.91, p.979 – 1008.

Amcoff, Ö., (2001) Ore Petrology. Department of Earth Science, Uppsala University, p.13, 23 – 25.

Barton, P.B and Toulmin, P. (1966) Phase relations involving sphalerite in the Fe-Zn-S system. Economic

Geology vol.61, p. 815 – 849.

Berglund, S., and Ekström, T.K. (1980) Arsenopyrite and Sphalerite as T-P indicators in Sulphide ores from

Northern Sweden. Mineralium Deposita, vol.15, p.175 – 187.

Clark, A.H. (1965) Iron-deficient Low-temperature Pyrrhotite. Nature vol.205, p.792 – 793.

Craig, J.R and Vaughan D.J (1994) Ore microscopy & ore petrography, 2nd

ed. John Wiley & sons, Inc. Canada,

p. 1 – 17.

Geijer, P. and Magnusson, N.H. (1944) De Mellansvenska järnmalmernas geologi. Sveriges Geologiska

Undersökning Ca 35, p.527 – 543.

Hutcheon, I. (1978) Calculation of metamorphic pressure using the sphalerite – pyrrhotite – pyrite equilibrium.

American Mineralogist, vol.63, p.87 – 95.

Hutchison M. and Scott S.D. (1980) Sphalerite Geobarometry applied to metamorphosed 27ulphide ores of the

Swedish Caledonides and U.S Appalachians. Norges Geologiska Undersøkelse, vol.360, p.59 – 71, 1981.

Hutchison M. and Scott S.D. (1981) Sphalerite Geobarometry in the Cu – Fe – Zn – S System. Economic

Geology, vol.76, p.143 – 153.

Koh, Y-K., Choi, S-G., So, C-S., Choi, S-H. and Uchida, E. (1992) Application of Arsenopyrite geothermometry

and sphalerite geobarometry to the Taebaek Pb – Zn (– Ag) deposit at Yeonhwa I mine, Republic of Korea.

Mineralium Deposita, vol.27, p.58 – 65.

Kretschmar, U. and Scott, S.D. (1976) Phase relations involving arsenopyrite in the Fe-As-S system and their

applications. Canadian Mineralogist, vol.14, p.364 – 386.

Lager, I. (2001) The geology of the Palaeoproterozoic limestone-hosted Dannemora iron deposit, Sweden.

Sveriges Geologiska Undersökning Rapporter och meddelanden 107, 49pp.

Lynch, G. and Mengel, F. (1985) Metamorphism of Arsenopyrite – Pyrite –Sphalerite –Pyrrhotite Lenses,

Western Cape Breton Island, Nova Scotia. The Canadian Mineralogist, vol.33, p.105 – 114.

Martín, J.D. and Soler I Gil, A. (2004) An intergraded thermodynamic mixing model for sphalerite

geobarometry from 300 to 850o C and up to 1GPa. Geochemical et Cosmochimica Acta, vol.69, no.4, p.995 –

1006, 2005.

Uppsala University Taking the Temperature & Pressure on Dannemora.

28

Nesse, W.D. (2000) Introduction to Mineralogy. Oxford University Press,Inc, p.169 -174.

Ribbe, P.H., Editor (1973) Sulfide Mineralogy – Mineralogical Society of America Short Course Notes,

Mineralogical Society of America, vol.1, 284pp.

Scott, S.D and Barnes, H. (1971) Sphalerite Geothermometry and Geobarometry. Economic Geology, vol. 66, p.

653 – 669.

Scott, S.D. (1973) Experimental Calibration of the Sphalerite Geobarometer, Economic Geology, vol. 68, p.466

– 474.

Scott, S.D. (1976) Application of sphalerite geobarometer to regionally metamorphosed terrains. American

Mineralogist, vol.61, p.661 – 670.

Sharp, Z.D., Essene, E.J, and Kelly, W.C. (1985) A re-examination of Arsenopyrite geothermometer: Pressure

considerations and applications to natural assemblages. Canadian Mineralogist, vol.23, p.517 – 534.

Stålhös, G. (1991) Beskrivning till berggrundskartorna Östhammar NV, NO, SV, SO. Sveriges Geologiska

Undersökning, Af 161, 166, 169, 172, 249pp.

Sundblad, K., Zachrisson, E., Smeds, S.-A., Berglund, S. and Ålinder, C. (1984) Sphalerite Geobarometry and

Arsenopyrite Geothermometry Applied to Metamorphosed Sulfide Ores in the Swedish Caledonides. Economic

Geology, vol 79, p. 1660 – 1668.

Web site of the University o Microprobe Laboratory: http://probelab.geo.edu/electron_microprobe.html,

2009.05.13, 10:11.

Figures:

1. Lantmäteriet digitala kartbibliotek:

http://butiken.metria.se/hamtplats/digibib/order_133840_266763_1.jpg, 2009-05-12, 14:38.

2. Lantmäteriet digitala kartbibliotek:

http://butiken.metria.se/hamtplats/digibib/order_133843_266774_2.jpg, 2009-05-12, 14:40.

3. http://www4.nau.edu/microanalysis/Microprobe/img/EMP.gif, 2009-05-13, 10:11.

28. http://earthsci.org/education/teacher/basicgeol/meta/meta.html, 2009-09-16, 10:41.

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11. Appendices

11.1 Tables recalculated from the EMPA result.

11.1.1 Recalculated sphalerite analyses where Zn+S+Fe=100 at.%

Sample No., Point No. S Fe Zn

3012–124.25, 1 50,11 6,50 43,39

3012–124.25, 2 51,08 6,94 41,98

3012–124.25, 3 50,79 6,03 43,18

3012–130.30, 1 50,91 8,28 40,81

3012–130.30, 2 49,95 7,25 42,80

3012–130.30, 6 49,94 6,13 43,93

3012–130.30, 15 50,33 6,45 43,24

3012–130.30, 18 50,83 6,18 42,99

3015–100.60, 12 51,62 4,25 44,14

3015–100.60, 18 50,72 4,32 44,96

3015–100.60, 20 51,39 3,83 44,78

3015–104.25, 1 51,20 6,54 42,26

3015–104.25, 17 50,39 7,31 42,30

3015–104.25, 30 50,47 8,21 41,32

3015–104.25, 37 51,16 7,29 41,55

11.1.2 Table of results from calculating equation 3.

Sample No. Pressure (kb) Comments

3012-124.25 4,57 Sphalerite in contact with pyrrhotite

3012-124.25 3,19 Sphalerite in contact with pyrrhotite

3012-124.25 5,55 Sphalerite in contact with pyrrhotite

3012-130.30 0,33 Sphalerite in pyrite

3012-130.30 2,85 Sphalerite in pyrite and in cont. with pyrrhotite

3012-130.30 5,56 Sphalerite in pyrrhotite

3012-130.30 4,63 Sphalerite in contact with pyrite and pyrrhotite

3012-130.30 5,15 Sphalerite in contact with pyrrhotite

3015-100.60 10,73 Sphalerite with high concentration Mn

3015-100.60 10,75 Sphalerite with high concentration Mn

3015-100.60 12,38 Sphalerite with high concentration Mn

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3015-104.25 4,12 Sphalerite in contact with pyrrhotite

3015-104.25 2,58 Sphalerite in pyrite

3015-104.25 0,63 Sphalerite in contact with pyrite and pyrrhotite

3015-104.25 2,36 Sphalerite in contact with pyrrhotite (close to pyrite)

11.2 Electron Microprobe Analyse results.

Sample: 3012-124.25 Point 1 Sphalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,566 33,298 49,9867

Cd 0,198 0,1964 0,0841

Mn 0,1948 0,1933 0,1693

Fe 7,5826 7,522 6,4824

Cu 0 0 0

Zn 59,2637 58,7904 43,2775

Hg 0 0 0

Total: 100,8051 100 100

Sample: 3012-124.25 Point 2 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,5758 34,1686 50,9166

Cd 0,2092 0,2129 0,0905

Mn 0,2494 0,2538 0,2207

Fe 7,9473 8,0876 6,9186

Cu 0,0008 0,0008 0,0006

Zn 56,2826 57,2763 41,853

Hg 0 0 0

Total: 98,2651 100 100

Sample: 3012-124.25 Point 3 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,7156 33,8877 50,6657

Cd 0,1358 0,1365 0,0582

Mn 0,2108 0,2119 0,1848

Fe 6,97 7,0056 6,0128

Cu 0 0 0

Zn 58,46 58,7584 43,0785

Hg 0 0 0

Total: 99,4921 100 100

Sample: 3012-124.25 Point 4 Chalcopyrite CuFeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 35,713 35,8638 51,1719

Cd 0 0 0

Mn 0 0 0

Fe 27,1294 27,2439 22,3156

Cu 34,5227 34,6684 24,9565

Zn 2,2146 2,2239 1,556

Hg 0 0 0

Total: 99,5797 100 100

Sample: 3012-124.25 Point 5 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0126 0,0128 0,0228

S 39,2805 40,0516 53,7781

Fe 58,7817 59,9356 46,1992

Mn 0 0 0

Total: 98,0748 100 100

Sample: 3012-124.25 Point 6 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

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Mg 0 0 0

S 39,7151 41,6915 55,467

Fe 55,5443 58,3085 44,533

Mn 0 0 0

Total: 95,2594 100 100

Sample: 3012-124.25 Point 7 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 39,4047 40,8832 54,6417

Fe 56,9562 59,0933 45,34

Mn 0,0227 0,0235 0,0183

Total: 96,3836 100 100

Sample: 3012-124.25 Point 8 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 22,1828 22,0449 36,4128

Fe 35,3791 35,1592 33,3386

Ni 0 0 0

Co 0 0 0

As 43,0636 42,7959 30,2486

Sb 0 0 0

Total: 100,6255 100 100

Sample: 3012-124.25 Point 9 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,8481 22,1176 36,6568

Fe 33,0653 33,4729 31,8475

Ni 0 0 0

Co 0 0 0

As 43,8686 44,4095 31,4957

Sb 0 0 0

Total: 98,782 100 100

Sample: 3012-124.25 Point 10 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,6349 22,0863 36,7233

Fe 31,6065 32,2661 30,7984

Ni 0 0 0

Co 0 0 0

As 44,7145 45,6476 32,4783

Sb 0 0 0

Total: 97,9559 100 100

Sample: 3012-124.25 Point 11 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,0841 21,9122 36,489

Fe 31,0799 32,3006 30,8781

Ni 0,0288 0,03 0,0273

Co 0 0 0

As 44,028 45,7572 32,6056

Sb 0 0 0

Total: 96,2208 100 100

Sample: 3012-124.25 Point 12 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0087 0,0086 0,0154

S 39,4483 39,1139 52,8045

Fe 61,398 60,8775 47,1801

Mn 0 0 0

Total: 100,855 100 100

Sample: 3012-124.25 Point 13 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,049 0,0482 0,0859

S 39,6879 39,0645 52,7315

Fe 61,8296 60,8583 47,1598

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Mn 0,0294 0,029 0,0228

Total: 101,5959 100 100

Sample: 3012-124.25 Point 14 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 39,3726 39,073 52,7659

Fe 61,3527 60,8858 47,2016

Mn 0,0415 0,0412 0,0325

Total: 100,7668 100 100

Sample: 3012-124.25 Point 15 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0054 0,0054 0,0096

S 39,5233 39,1475 52,8413

Fe 61,4311 60,8471 47,1491

Mn 0 0 0

Total: 100,9598 100 100

Sample: 3012-130.30 Point 1 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,7819 34,0912 50,7424

Cd 0,2475 0,2498 0,106

Mn 0,1661 0,1676 0,1456

Fe 9,5733 9,661 8,2549

Cu 0,0981 0,099 0,0743

Zn 55,2257 55,7314 40,6768

Hg 0 0 0

Total: 99,0926 100 100

Sample: 3012-130.30 Point 2 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,166 33,1815 49,8217

Cd 0,2993 0,2994 0,1282

Mn 0,1301 0,1302 0,1141

Fe 8,3904 8,3943 7,2356

Cu 0,0071 0,0071 0,0054

Zn 57,9606 57,9875 42,695

Hg 0 0 0

Total: 99,9535 100 100

Sample: 3012-130.30 Point 3 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 38,7925 38,5602 52,2337

Fe 61,6805 61,3112 47,6777

Ni 0 0 0

Co 0,0894 0,0888 0,0655

As 0,0401 0,0398 0,0231

Sb 0 0 0

Total: 100,6025 100 100

Sample: 3012-130.30 Point 4 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 38,829 38,5594 52,2269

Fe 61,8703 61,4406 47,7731

Mn 0 0 0

Total: 100,6993 100 100

Sample: 3012-130.30 Point 5 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,004 0,0039 0,007

S 38,6351 38,4552 51,115

Fe 61,8288 61,5409 47,8779

Mn 0 0 0

Total: 100,4679 100 98,9999

Sample: 3012-130.30 Point 6 Shpalerite (Zn,Fe)S

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Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 32,9459 33,1061 49,8118

Cd 0,2468 0,248 0,1064

Mn 0,1277 0,1284 0,1127

Fe 7,0438 7,0781 6,1136

Cu 0,0395 0,0397 0,0301

Zn 59,1121 59,3997 43,8254

Hg 0 0 0

Total: 99,5158 100 100

Sample: 3012-130.30 Point 7 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 24,9679 25,3216 40,3999

Fe 36,3635 36,8787 33,7775

Ni 0,0184 0,0186 0,0162

Co 0,065 0,0659 0,0572

As 37,1884 37,7152 25,7492

Sb 0 0 0

Total: 98,6032 100 100

Sample: 3012-130.30 Point 8 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,5474 21,2742 35,3513

Fe 36,0984 35,6407 33,9987

Ni 0 0 0

Co 0,0717 0,0707 0,064

As 43,5668 43,0144 30,586

Sb 0 0 0

Total: 101,2843 100 100

Sample: 3012-130.30 Point 9 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 55,0265 53,7171 66,9189

Fe 47,3055 46,1798 33,0257

Co 0,0035 0,0034 0,0023

As 0,1021 0,0997 0,0531

Total: 102,4376 100 100

Sample: 3012-130.30 Point 10 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 54,6935 54,1433 67,2854

Fe 46,3226 45,8567 32,7146

Mg 0 0 0

Mn 0 0 0

Total: 101,0161 100 100

Sample: 3012-130.30 Point 13 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,5634 21,5302 35,671

Fe 35,9535 35,8982 34,1431

Ni 0,0213 0,0213 0,0193

Co 0 0 0

As 42,616 42,5503 30,1666

Sb 0 0 0

Total: 100,1542 100 100

Sample: 3012-130.30 Point 15 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,5807 33,4802 50,2008

Cd 0,2231 0,2224 0,0951

Mn 0,1437 0,1433 0,1254

Fe 7,4984 7,4759 6,4351

Cu 0 0 0

Zn 58,8543 58,6782 43,1436

Hg 0 0 0

Total: 100,3002 100 100

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Sample: 3012-130.30 Point 16 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 22,4862 21,9332 36,2112

Fe 36,6615 35,76 33,8923

Ni 0 0 0

Co 0,0415 0,0404 0,0363

As 43,332 42,2664 29,8602

Sb 0 0 0

Total: 102,5212 100 100

Sample: 3012-130.30 Point 17 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,0351 20,7888 34,7289

Fe 35,8191 35,3997 33,9488

Ni 0,0177 0,0175 0,0159

Co 0 0 0

As 44,3128 43,794 31,3064

Sb 0 0 0

Total: 101,1847 100 100

Sample: 3012-130.30 Point 18 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,45 33,9092 50,7042

Cd 0,2658 0,2693 0,1149

Mn 0,1355 0,1374 0,1199

Fe 7,08 7,1772 6,1609

Cu 0,0256 0,026 0,0196

Zn 57,689 58,4809 42,8805

Hg 0 0 0

Total: 98,6459 100 100

Sample: 3012-130.30 Point 19 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,5782 38,9746 52,6709

Cd 0 0 0

Mn 0 0 0

Fe 61,829 60,8861 47,2358

Cu 0,0466 0,0458 0,0313

Zn 0,0949 0,0935 0,062

Hg 0 0 0

Total: 101,5487 100 100

Sample: 3012-130.30 Point 20 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0021 0,0021 0,0038

S 39,3603 39,9256 53,6534

Fe 59,2215 60,0723 46,3428

Mn 0 0 0

Total: 98,5839 100 100

Sample: 3015-100.60 Point 2 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 17,7167 17,4367 30,2184

Fe 34,2444 33,7032 33,5307

Ni 0 0 0

Co 0,0843 0,082 0,0782

As 49,5605 48,7772 36,1727

Sb 0 0 0

Total: 101,6059 99,9991 100

Sample: 3015-100.60 Point 3 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 20,9499 20,5373 34,4387

Fe 35,4854 34,7866 33,4871

Ni 0 0 0

Co 0,0858 0,0841 0,0767

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As 45,4878 44,592 31,9975

Sb 0 0 0

Total: 102,0089 100 100

Sample: 3015-100.60 Point 4 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 20,3236 20,0067 33,6995

Fe 35,6626 35,1066 33,9469

Ni 0 0 0

Co 0 0 0

As 45,5976 44,8867 32,3536

Sb 0 0 0

Total: 101,5838 100 100

Sample: 3015-100.60 Point 5 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 28,9237 28,0999 43,7235

Fe 38,0186 36,9358 32,9929

Ni 0 0 0

Co 0,0292 0,0284 0,024

As 35,9525 34,9285 23,2565

Sb 0,0077 0,0074 0,0031

Total: 102,9317 100 100

Sample: 3015-100.60 Point 6 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,9877 21,5182 35,6773

Fe 36,4367 35,6588 33,9404

Ni 0 0 0

Co 0 0 0

As 43,7573 42,823 30,3823

Sb 0 0 0

Total: 102,1817 100 100

Sample: 3015-100.60 Point 7 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,4948 20,984 35,0557

Fe 35,4653 34,6224 33,2041

Ni 0 0 0

Co 0,024 0,0234 0,0213

As 45,4504 44,3702 31,7189

Sb 0 0 0

Total: 102,4345 100 100

Sample: 3015-100.60 Point 8 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 18,8913 18,2231 31,3379

Fe 34,8813 33,6474 33,2172

Ni 0,0298 0,0287 0,027

Co 0,1128 0,1088 0,1018

As 49,7519 47,992 35,3161

Sb 0 0 0

Total: 103,6671 100 100

Sample: 3015-100.60 Point 9 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 18,7268 18,633 31,8452

Fe 34,7533 34,5793 33,9266

Ni 0,0196 0,0195 0,0182

Co 0,034 0,0338 0,0314

As 46,9695 46,7344 34,1786

Sb 0 0 0

Total: 100,5032 100 100

Sample: 3015-100.60 Point 10 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 18,3659 18,1988 31,2203

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Fe 35,0131 34,6945 34,168

Ni 0,0196 0,0194 0,0182

Co 0,1368 0,1355 0,1265

As 47,383 46,9518 34,467

Sb 0 0 0

Total: 100,9184 100 100

Sample: 3015-100.60 Point 11 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,5681 21,6782 35,8492

Fe 35,7962 35,979 34,1561

Ni 0 0 0

Co 0,1836 0,1846 0,1661

As 41,929 42,1432 29,8221

Sb 0,015 0,015 0,0065

Total: 99,4919 100 100

Sample: 3015-100.60 Point 12 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,8779 33,8675 50,6781

Cd 0,2623 0,2622 0,1119

Mn 1,9295 1,9289 1,6843

Fe 4,8511 4,8496 4,1658

Cu 0,0271 0,0271 0,0205

Zn 59,0829 59,0647 43,3394

Hg 0 0 0

Total: 100,0308 100 100

Sample: 3015-100.60 Point 13 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 54,3177 53,1652 66,4137

Fe 47,85 46,8348 33,5863

Mg 0 0 0

Mn 0 0 0

Total: 102,1677 100 100

Sample: 3015-100.60 Point 14 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 53,3386 52,3671 65,8823

Fe 46,9428 46,0878 33,2859

As 1,5737 1,5451 0,8318

Ni 0 0 0

Co 0 0 0

Total: 101,8551 100 100

Sample: 3015-100.60 Point 16 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 54,7411 53,755 66,9439

Fe 47,011 46,1641 33,0035

As 0,0162 0,016 0,0085

Ni 0,0315 0,031 0,0211

Co 0,0345 0,0339 0,023

Total: 101,8343 100 100

Sample: 3015-100.60 Point 18 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,2144 33,1141 49,828

Cd 0,2139 0,2133 0,0915

Mn 1,8991 1,8934 1,6626

Fe 4,9291 4,9142 4,2451

Cu 0,0107 0,0106 0,0081

Zn 60,0357 59,8544 44,1647

Hg 0 0 0

Total: 100,3029 100 100

Sample: 3015-100.60 Point 19 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

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S 54,8662 54,6154 67,7027

Fe 45,58 45,3716 32,2879

Mg 0 0 0

Mn 0,013 0,013 0,0094

Total: 100,4592 100 100

Sample: 3015-100.60 Point 20 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,6867 33,6246 50,4319

Cd 0,2379 0,2375 0,1016

Mn 1,9675 1,9638 1,7188

Fe 4,3728 4,3648 3,7581

Cu 0,0642 0,064 0,0485

Zn 59,8557 59,7453 43,9411

Hg 0 0 0

Total: 100,1848 100 100

Sample: 3015-104.25 Point 1 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,874 34,051 50,7903

Cd 0,2439 0,2452 0,1044

Mn 0,7195 0,7232 0,6296

Fe 7,5311 7,5705 6,4824

Cu 0,0994 0,0999 0,0752

Zn 57,0124 57,3102 41,9181

Hg 0 0 0

Total: 99,4803 100 100

Sample: 3015-104.25 Point 2 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 40,0778 40,4002 54,1601

Cd 0 0 0

Mn 0 0 0

Fe 58,8683 59,3419 45,669

Cu 0,0712 0,0717 0,0485

Zn 0,1847 0,1862 0,1224

Hg 0 0 0

Total: 99,202 100 100

Sample: 3015-104.25 Point 3 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 54,5476 53,8511 67,1029

Fe 46,0728 45,4845 32,5368

Ni 0,0416 0,0411 0,028

Co 0 0 0

As 0,6313 0,6233 0,3323

Total: 101,2933 100 100

Sample: 3015-104.25 Point 4 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,5999 21,5801 35,7596

Fe 35,6859 35,6534 33,9157

Ni 0 0 0

Co 0,0003 0,0003 0,0002

As 42,8052 42,7662 30,3245

Sb 0 0 0

Total: 100,0913 100 100

Sample: 3015-104.25 Point 5 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 39,8188 39,9532 53,6831

Fe 59,8449 60,0468 46,3169

Mn 0 0 0

Total: 99,6637 100 100

Sample: 3015-104.25 Point 6 Arsenopyrite FeAsS

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Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,6809 21,3762 35,5298

Fe 35,7207 35,2187 33,6047

Ni 0 0 0

Co 0 0 0

As 44,0011 43,3827 30,8557

Sb 0,0227 0,0224 0,0098

Total: 101,4254 100 100

Sample: 3015-104.25 Point 8 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 55,0774 53,4521 66,7023

Fe 47,6922 46,2848 33,1572

Ni 0 0 0

Co 0 0 0

As 0,2711 0,2631 0,1405

Total: 103,0407 100 100

Sample: 3015-104.25 Point 10 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 53,2463 53,3261 66,5738

Fe 46,4716 46,5413 33,3553

Ni 0 0 0

Co 0 0 0

As 0,1324 0,1326 0,0709

Total: 99,8503 100 100

Sample: 3015-104.25 Point 11 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 21,0986 21,1539 35,3006

Fe 34,2863 34,3763 32,9317

Ni 0 0 0

Co 0,065 0,0652 0,0592

As 44,2884 44,4046 31,7085

Sb 0 0 0

Total: 99,7383 100 100

Sample: 3015-104.25 Point 13 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 38,815 39,4373 53,1468

Fe 59,607 60,5627 46,8532

Mn 0 0 0

Total: 98,422 100 100

Sample: 3015-104.25 Point 14 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0137 0,014 0,0249

S 38,6359 39,5555 53,2625

Fe 59,0255 60,4305 46,7126

Mn 0 0 0

Total: 97,6751 100 100

Sample: 3015-104.25 Point 15 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 37,3408 38,4813 52,1447

Fe 59,6953 61,5187 47,8553

Mn 0 0 0

Total: 97,0361 100 100

Sample: 3015-104.25 Point 17 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,2761 33,3626 49,967

Cd 0,1951 0,1956 0,0836

Mn 0,6548 0,6565 0,5737

Fe 8,4098 8,4316 7,2493

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Cu 0,2285 0,229 0,1731

Zn 56,9766 57,1247 41,9533

Hg 0 0 0

Total: 99,7409 100 100

Sample: 3015-104.25 Point 18 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,5316 53,1385 66,3907

Fe 46,288 46,8228 33,583

Ni 0 0 0

Co 0,0383 0,0387 0,0263

As 0 0 0

Total: 98,8579 100 100

Sample: 3015-104.25 Point 18 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,5316 53,1385 66,3907

Fe 46,288 46,8228 33,583

Ni 0 0 0

Co 0,0383 0,0387 0,0263

As 0 0 0

Total: 98,8579 100 100

Sample: 3015-104.25 Point 19 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 37,3555 39,3087 53,0127

Fe 57,6756 60,6913 46,9873

Mn 0 0 0

Total: 95,0311 100 100

Sample: 3015-104.25 Point 20 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0029 0,003 0,0054

S 37,2312 38,3067 51,9588

Fe 59,9582 61,6903 48,0358

Mn 0 0 0

Total: 97,1923 100 100

Sample: 3015-104.25 Point 21 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 20,6351 20,6205 34,5077

Fe 35,3829 35,3578 33,9677

Ni 0,0039 0,0039 0,0035

Co 0 0 0

As 44,049 44,0178 31,5211

Sb 0 0 0

Total: 100,0709 100 100

Sample: 3015-104.25 Point 22 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 20,4852 20,559 34,4371

Fe 35,0906 35,217 33,8643

Ni 0 0 0

Co 0 0 0

As 44,0654 44,224 31,6986

Sb 0 0 0

Total: 99,6412 100 100

Sample: 3015-104.25 Point 24 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,5358 52,8893 66,2933

Fe 45,7475 46,0554 33,1395

Ni 0 0 0

Co 0,0087 0,0088 0,006

As 1,0395 1,0465 0,5612

Total: 99,3315 100 100

Uppsala University Taking the Temperature & Pressure on Dannemora.

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Sample: 3015-104.25 Point 25 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 53,0606 52,6486 66,106

Fe 46,3776 46,0175 33,1697

Ni 0 0 0

Co 0 0,0523 0,0357

As 1,2916 1,2816 0,6886

Total: 100,7298 100 100

Sample: 3015-104.25 Point 26 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 53,1033 53,2011 66,4586

Fe 46,5762 46,6619 33,4624

Ni 0 0 0

Co 0,0401 0,0402 0,0273

As 0,0966 0,0968 0,0517

Total: 99,8162 100 100

Sample: 3015-104.25 Point 28 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0 0 0

S 37,559 38,8804 52,5644

Fe 59,0423 61,1196 47,4356

Mn 0 0 0

Total: 96,6013 100 100

Sample: 3015-104.25 Point 29 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 37,5244 38,6069 52,2842

Fe 59,5826 61,3015 47,6585

Ni 0 0 0

Co 0,0258 0,0265 0,0196

As 0,0633 0,0651 0,0377

Total: 97,1961 100 100

Sample: 3015-104.25 Point 30 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,2424 33,4702 50,0315

Cd 0,3139 0,3159 0,1347

Mn 0,7938 0,7993 0,6972

Fe 9,4187 9,4833 8,1378

Cu 0,0504 0,0508 0,0384

Zn 55,5001 55,8805 40,9604

Hg 0 0 0

Total: 99,3193 100 100

Sample: 3015-104.25 Point 31 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0237 0,0245 0,0436

S 37,7103 39,0284 52,7066

Fe 58,8887 60,9471 47,2498

Mn 0 0 0

Total: 96,6227 100 100

Sample: 3015-104.25 Point 32 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,1362 39,0738 52,7688

Cd 0 0 0

Mn 0 0 0

Fe 60,9943 60,897 47,2119

Cu 0 0 0

Zn 0,0292 0,0292 0,0193

Hg 0 0 0

Total: 100,1597 100 100

Sample: 3015-104.25 Point 33 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

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S 21,3355 21,6088 35,851

Fe 34,5603 35,003 33,338

Ni 0,0628 0,0635 0,0577

Co 0 0 0

As 42,7587 43,3064 30,7453

Sb 0,0181 0,0183 0,008

Total: 98,7354 100 100

Sample: 3015-104.25 Point 34 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

Mg 0,0032 0,0032 0,0059

S 38,0421 39,1225 52,8162

Fe 59,1932 60,8743 47,1779

Mn 0 0 0

Total: 97,2385 100 100

Sample: 3015-104.25 Point 34 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,6745 39,4714 53,2154

Fe 60,5131 60,2034 46,595

Ni 0 0 0

Co 0,0129 0,0128 0,0094

As 0,314 0,3124 0,1802

Total: 100,5145 100 100

Sample: 3015-104.25 Point 36 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 53,1729 53,5475 66,7857

Fe 45,8596 46,1827 33,0664

Ni 0 0 0

Co 0,0265 0,0267 0,0181

As 0,2414 0,2431 0,1298

Total: 99,3004 100 100

Sample: 3015-104.25 Point 37 Shpalerite (Zn,Fe)S

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 33,9025 33,9613 50,629

Cd 0,2785 0,279 0,1186

Mn 0,8947 0,8963 0,7797

Fe 8,4146 8,4292 7,2138

Cu 0,1855 0,1858 0,1398

Zn 56,151 56,2484 41,1191

Hg 0 0 0

Total: 99,8268 100 100

Sample: 3015-104.25 Point 38 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,9902 39,7718 53,5163

Fe 60,3549 60,0251 46,3668

Ni 0 0 0

Co 0 0 0

As 0,2042 0,2031 0,1169

Total: 100,5493 100 100

Sample: 3015-104.25 Point 39 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 54,6911 54,3469 67,4999

Fe 45,6507 45,3633 32,3443

Ni 0 0 0

Co 0,0121 0,0121 0,0082

As 0,2795 0,2777 0,1476

Total: 100,6334 100 100

Sample: 3015-104.25 Point 41 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,5414 52,9134 66,2104

Fe 46,5707 46,9004 33,6899

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Ni 0 0 0

Co 0 0 0

As 0,1849 0,1862 0,0997

Total: 99,297 100 100

Sample: 3015-104.25 Point 42 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,8153 53,563 66,7702

Fe 45,7494 46,3971 33,2027

Ni 0,0097 0,0098 0,0067

Co 0,0297 0,0301 0,0204

As 0 0 0

Total: 98,6041 100 100

Sample: 3015-104.25 Point 43 Pyrite FeS2

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 52,7498 53,2158 66,4989

Fe 46,0486 46,4554 33,3253

Ni 0 0 0

Co 0 0 0

As 0,3259 0,3288 0,1758

Total: 99,1243 100 100

Sample: 3015-104.25 Point 44 Arsenopyrite FeAsS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 20,5866 20,474 34,4231

Fe 34,1615 33,9748 32,792

Ni 0 0 0

Co 0,0663 0,0659 0,0602

As 45,7354 45,4853 32,7247

Sb 0 0 0

Total: 100,5498 100 100

Sample: 3015-104.25 Point 45 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,6454 39,3912 53,0992

Cd 0,0024 0,0024 0,001

Mn 0 0 0

Fe 60,9976 60,6064 46,8998

Cu 0 0 0

Zn 0 0 0

Hg 0 0 0

Total: 100,6454 100 100

Sample: 3015-104.25 Point 46 Pyrrhotite Fe1-XS

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 39,3662 38,7529 52,4998

Fe 61,521 60,5624 47,1

Ni 0 0 0

Co 0,0214 0,021 0,0155

As 0,6742 0,6637 0,3847

Total: 101,5828 100 100

Sample:3015-100.70 Point 1 Pyrargyrite Ag3SbS3

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 16,5552 16,5097 40,2294

Ag 58,3451 58,1849 42,1391

Sb 22,7228 22,6604 14,5401

As 0,6459 0,6442 0,6717

Cu 0,4127 0,4115 0,5059

Zn 1,5211 1,5169 1,8125

Fe 0,0726 0,0724 0,1013

Total: 100,2754 100 100

Sample:3015-100.70 Point 2 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,0115 19,2366 41,0701

Uppsala University Taking the Temperature & Pressure on Dannemora.

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Ag 33,7047 34,1037 21,6407

Sb 25,966 26,2733 14,7709

As 0,4549 0,4603 0,4206

Cu 12,3021 12,4477 13,408

Zn 2,633 2,6641 2,7891

Fe 4,758 4,8143 5,9006

Total: 98,8302 100 100

Sample:3015-100.70 Point 3 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,3504 19,3122 41,2446

Ag 34,4812 34,4132 21,8439

Sb 26,2269 26,1753 14,7204

As 0,6564 0,6552 0,5987

Cu 12,2778 12,2536 13,2031

Zn 2,39 2,3853 2,498

Fe 4,8146 4,8052 5,8913

Total: 100,1973 100 100

Sample:3015-100.70 Point 5 Diaphorite Ag3Pb2Sb3S8

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 18,2268 17,7225 46,754

Ag 24,2766 23,6049 18,5083

Sb 27,1364 26,3856 18,3297

Pb 29,4011 28,5877 11,6693

As 0,9166 0,8913 1,0062

Cu 0,2273 0,221 0,2942

Zn 2,2339 2,1721 2,8099

Fe 0,4268 0,4149 0,6284

Total: 102,8455 100 100

Sample:3015-100.70 Point 6 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,281 19,6035 41,8139

Ag 33,8285 34,3944 21,8045

Sb 26,1084 26,5451 14,9096

Pb 0,203 0,2064 0,0681

As 0,0319 0,0324 0,0296

Cu 12,5561 12,7662 13,738

Zn 1,4544 1,4787 1,5466

Fe 4,8914 4,9733 6,0897

Total: 98,3547 100 100

Sample:3015-100.70 Point 7 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,6352 19,8658 42,139

Ag 33,6207 34,0156 21,445

Sb 26,2538 26,5622 14,8366

Pb 0,0699 0,0707 0,0232

As 0,0782 0,0791 0,0718

Cu 11,9873 12,1281 12,9791

Zn 1,9918 2,0152 2,0961

Fe 5,2022 5,2633 6,4092

Total: 98,8391 100 100

Sample:3015-100.70 Point 8 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,4088 19,47 41,6335

Ag 34,8877 34,9976 22,2427

Sb 26,0253 26,1073 14,7006

Pb 0,2792 0,2801 0,0927

As 0 0 0

Cu 12,2707 12,3093 13,2796

Zn 1,8953 1,9013 1,9937

Fe 4,9189 4,9344 6,0572

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Total: 99,6859 100 100

Sample:3015-100.70 Point 9 Tetrahedrite (Cu,Fe,Ag,Zn)12Sb4S13

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 19,3167 19,6095 41,8112

Ag 34,1217 34,6388 21,9513

Sb 25,8415 26,2331 14,7289

Pb 0,2487 0,2525 0,0833

As 0 0 0

Cu 12,4357 12,6241 13,5801

Zn 1,5718 1,5956 1,6683

Fe 4,971 5,0464 6,1769

Total: 98,5071 100 100

Sample:3015-100.70 Point 11 Pyrargyrite Ag3SbS3

Elements: Conc. (wt%) Norm Conc. (wt%) Norm Conc. (at%)

S 17,0381 16,8672 41,0507

Ag 58,0577 57,4752 41,5747

Sb 22,3005 22,0768 14,1484

Pb 1,3578 1,3441 0,5062

As 0 0 0

Cu 1,0562 1,0456 1,2838

Zn 1,1311 1,1197 1,3364

Fe 0,0722 0,0714 0,0998

Total: 101,0136 100 100

Traverse results:

AT%

Traverse 1 S Sb Fe Ni Co As SUM

301510060 tr1 31,611 0 33,405 0 0,097 34,887 100

301510060 tr1 30,704 0 33,195 0 0 36,1 99,999

301510060 tr1 30,296 0 33,089 0 0,096 36,518 99,999

301510060 tr1 30,449 0 33,229 0 0,159 36,163 100

301510060 tr1 30,415 0 33,216 0 0,103 36,267 100,001

301510060 tr1 30,188 0 33,546 0,042 0,17 36,054 100

301510060 tr1 30,412 0 33,185 0 0,105 36,298 100

301510060 tr1 30,589 0 33,869 0 0,105 35,437 100

301510060 tr1 30,931 0 33,95 0,018 0,148 34,952 99,999

301510060 tr1 31,851 0 33,184 0 0,131 34,835 100,001

301510060 tr1 32,058 0 33,973 0 0,097 33,873 100,001

301510060 tr1 32,028 0 33,402 0 0,093 34,477 100

301510060 tr1 32,263 0,007 33,059 0,005 0,084 34,583 100,001

301510060 tr1 31,695 0 33,461 0 0,058 34,786 100

301510060 tr1 31,067 0,003 33,439 0 0,118 35,373 100

301510060 tr1 31,564 0 33,029 0 0,055 35,353 100,001

301510060 tr1 31,037 0 33,961 0 0,065 34,937 100

301510060 tr1 31,576 0 33,25 0 0,082 35,092 100

301510060 tr1 30,844 0 33,618 0,017 0,016 35,505 100

301510060 tr1 31,509 0,014 33,504 0 0,066 34,907 100

301510060 tr1 31,8 0 33,751 0 0,018 34,431 100

301510060 tr1 35,511 0 32,388 0 0,187 31,914 100

301510060 tr1 34,997 0,004 33,246 0 0,176 31,577 100

301510060 tr1 36,23 0 32,903 0,001 0,199 30,667 100

301510060 tr1 35,203 0 33,321 0 0,125 31,35 99,999

AT%

Traverse 2 S Sb Fe Ni Co As SUM

301510060 tr2 31,865 0 33,543 0 0,12 34,472 100

301510060 tr2 31,436 0 34,052 0 0,204 34,308 100

301510060 tr2 31,225 0 33,797 0 0,129 34,849 100

301510060 tr2 31,218 0 33,531 0 0,072 35,18 100,001

301510060 tr2 30,85 0 33,504 0 0,114 35,532 100

301510060 tr2 30,6 0 33,782 0 0,123 35,495 100

Uppsala University Taking the Temperature & Pressure on Dannemora.

45

301510060 tr2 30,731 0 33,277 0 0,168 35,824 100

301510060 tr2 31,155 0 33,894 0 0,086 34,865 100

301510060 tr2 31,13 0 33,135 0 0,104 35,632 100,001

301510060 tr2 31,219 0 33,4 0 0,116 35,265 100

301510060 tr2 30,489 0 33,584 0 0,136 35,79 99,999

301510060 tr2 31,038 0 33,657 0,002 0,097 35,205 99,999

301510060 tr2 30,904 0 33,369 0 0,054 35,674 100,001

301510060 tr2 30,007 0 33,543 0,017 0,073 36,36 100

301510060 tr2 29,962 0 34,076 0 0,152 35,811 100,001

301510060 tr2 30,678 0 34,322 0,002 0,157 34,84 99,999

301510060 tr2 30,934 0 33,101 0 0,177 35,789 100,001

301510060 tr2 31,361 0 33,151 0 0,173 35,316 100,001

301510060 tr2 31,285 0 33,112 0 0,124 35,478 99,999

301510060 tr2 31,231 0 33,917 0 0,101 34,751 100

301510060 tr2 30,339 0 33,952 0 0,118 35,591 100

301510060 tr2 29,834 0 33,575 0 0,106 36,486 100,001

301510060 tr2 30,187 0 33,619 0,001 0,154 36,04 100,001

301510060 tr2 30,484 0,013 33,55 0 0,119 35,834 100

301510060 tr2 31,583 0 33,674 0 0,109 34,634 100

301510060 tr2 33,88 0 33,374 0 0,161 32,584 99,999

301510060 tr2 30,711 0 33,378 0 0,115 35,796 100

301510060 tr2 30,847 0 33,238 0 0,078 35,836 99,999

301510060 tr2 30,584 0 33,718 0 0,161 35,537 100

301510060 tr2 30,508 0 33,474 0 0,06 35,958 100

301510060 tr2 31,89 0 31,426 0 0,092 36,593 100,001

301510060 tr2 34,732 0 33,18 0 0,014 32,074 100

301510060 tr2 34,868 0 32,551 0,033 0,013 32,534 99,999

301510060 tr2 34,704 0,015 33,479 0,019 0,021 31,762 100

301510060 tr2 36,195 0,004 33,918 0 0,015 29,868 100

301510060 tr2 35,642 0,019 33,086 0 0,028 31,225 100

301510060 tr2 36,959 0 32,885 0 0,015 30,141 100

301510060 tr2 37,844 0 32,879 0 0,018 29,26 100,001

301510060 tr2 37,193 0,01 33,73 0 0 29,067 100

301510060 tr2 35,661 0,035 32,735 0 0 31,569 100

301510060 tr2 35,512 0,176 33,423 0 0,027 30,862 100

301510060 tr2 35,675 0,01 33,626 0 0,006 30,683 100

301510060 tr2 35,9 0,01 32,924 0 0 31,166 100

301510060 tr2 36,191 0 33,803 0 0 30,006 100

301510060 tr2 35,095 0,001 33,906 0 0 30,998 100

301510060 tr2 35,368 0 33,594 0 0 31,038 100

301510060 tr2 35,944 0,008 33,99 0 0,033 30,025 100

301510060 tr2 35,895 0,024 33,5 0 0 30,581 100

301510060 tr2 35,397 0 33,292 0 0,041 31,27 100

301510060 tr2 35,952 0,002 32,622 0 0,014 31,41 100

AT%

Traverse 3 S Sb Fe Ni Co As SUM

301510060 tr3 30,141 0 33,749 0 0,084 36,027 100,001

301510060 tr3 30,763 0 32,304 0,012 0,068 36,854 100,001

301510060 tr3 30,855 0 33,071 0 0,034 36,04 100

301510060 tr3 30,93 0 33,145 0 0,045 35,88 100

301510060 tr3 30,308 0 33,441 0 0,054 36,197 100

301510060 tr3 30,697 0,002 32,886 0 0,018 36,397 100

301510060 tr3 30,705 0 33,485 0 0,037 35,774 100,001

301510060 tr3 30,694 0 33,662 0 0 35,644 100

301510060 tr3 32,447 0 33,6 0 0 33,953 100

301510060 tr3 32,999 0,003 33,676 0 0,001 33,322 100,001

301510060 tr3 34,078 0 33,713 0 0,026 32,183 100

301510060 tr3 34,214 0 33,934 0 0,036 31,816 100

301510060 tr3 33,738 0 33,493 0 0,034 32,735 100

301510060 tr3 33,689 0 33,046 0 0 33,264 99,999

301510060 tr3 33,749 0 33,267 0 0,016 32,969 100,001

301510060 tr3 33,533 0 32,967 0 0 33,5 100

301510060 tr3 34,019 0 33,135 0 0 32,847 100,001

301510060 tr3 33,607 0 32,909 0 0,072 33,411 99,999

Uppsala University Taking the Temperature & Pressure on Dannemora.

46

301510060 tr3 34,041 0 32,993 0,036 0,049 32,88 99,999

301510060 tr3 34,677 0,03 33,211 0,008 0 32,074 100

301510060 tr3 37,514 0,113 33,063 0,017 0 29,292 99,999

301510060 tr3 37,012 0,028 33,216 0 0 29,744 100

301510060 tr3 33,86 0,04 34,112 0 0,076 31,912 100

301510060 tr3 34,828 0 33,48 0 0 31,692 100

301510060 tr3 34,116 0,004 33,397 0 0,032 32,452 100,001

301510060 tr3 34,956 0 32,815 0 0,005 32,224 100

301510060 tr3 34,446 0 33,476 0 0,024 32,054 100

301510060 tr3 34 0,002 33,744 0,025 0,033 32,196 100

301510060 tr3 36,271 0 33,824 0 0,009 29,896 100

301510060 tr3 35,115 0 33,223 0,016 0,009 31,637 100

301510060 tr3 35,322 0 33,5 0,001 0 31,177 100

301510060 tr3 34,414 0 33,693 0 0 31,894 100,001

301510060 tr3 34,761 0 33,414 0 0 31,825 100

301510060 tr3 35,427 0,008 33,565 0 0,034 30,967 100,001

301510060 tr3 34,895 0 33,726 0 0 31,379 100

301510060 tr3 35,212 0 33,595 0,025 0 31,168 100

301510060 tr3 35,289 0,009 33,485 0,017 0 31,201 100,001

301510060 tr3 34,688 0,006 33,86 0,017 0 31,43 100,001

301510060 tr3 35,037 0 33,012 0 0,025 31,926 100

301510060 tr3 35,349 0,008 32,471 0 0,012 32,16 100

301510060 tr3 34,194 0 32,917 0 0 32,889 100

301510060 tr3 34,244 0 32,695 0 0,029 33,032 100

301510060 tr3 34,44 0 33,653 0 0,007 31,9 100

301510060 tr3 34,212 0 33,923 0 0 31,865 100

301510060 tr3 35,134 0 33,488 0 0,097 31,28 99,999

301510060 tr3 34,631 0 32,869 0 0 32,5 100

301510060 tr3 34,17 0 33,75 0,046 0 32,034 100

301510060 tr3 33,851 0 33,748 0 0 32,401 100

301510060 tr3 34,273 0 33,637 0 0 32,09 100

301510060 tr3 34,05 0 34,119 0 0 31,831 100