Timing and magma evolution of the Chelopech volcanic ... · Timing and magma evolution of the...

Schweizerische Mineralogische und Petrographische Mitteilungen 84 101ndash117 2004

0036-7699040084101 copy2004 Schweiz Mineral Petrogr Ges

1 University of Mining and Geology lsquoSt Ivan Rilskirsquo Department of Economic Geology Studentski grad Sofia 1700Bulgaria ltsstoykovmgubggt

2 Central Laboratory of Mineralogy and Crystallography Bulgarian Academy of Sciences Sofia 1113 Bulgaria3 Institute of Isotope Geology and Mineral Resources ETH-Zentrum CH-8092 Zuumlrich Switzerland4 Institute of Earth Sciences University of Geneva CH-1205 Geneva Switzerland

Timing and magma evolution of theChelopech volcanic complex (Bulgaria)

Stanislav Stoykov 1 Irena Peytcheva 23 Albrecht von Quadt 3 Robert Moritz 4 Martin Frank 3 and Denis Fontignie 4

Abstract

The Chelopech volcanic complex is located in the Central Srednogorie magmatic zone and hosts one of the largestCundashAu deposits in Europe Field observations and sedimentary relationships allow to distinguish three units of thevolcanic complex (I) dome-like bodies (II) lava to agglomerate flows and (III) the Vozdol lava breccias andvolcanites The volcanic rocks are porphyritic with plagioclase and amphibole phenocrysts quartz and biotite arerare The lava flows contain fully crystallised fine-grained enclaves of more basic composition Their mineral chem-istry indicates mingling and mixing between two parental magmas The geochemical evolution of the Chelopechvolcanic complex developed from intermediate to basic lavas but the evolution of the magmatism was more complexincluding magmatic differentiation assimilation mingling and mixing The trace element distribution is typical for anactive continental marginThe magmatic activity commenced at the northern border of the Chelopech region with the intrusion of dome-likebodies at 922 plusmn 03 Ma (UndashPb single zircon ID-TIMS dating) The products of the second and the third units aregeochronologically indistinguishable within the error uncertainties and representative samples yield a crystallisationage of 913 plusmn 03 Ma REE abundances reveal a striking positive Ce-anomaly in zircons of unit 2 and zircon core partsof unit 3 which relates to a higher oxidation state of the parental magmaSr and Nd isotopic compositions suggest a mixed mantle and crustal source of the Turonian magma Initial Sr ratiosrange between 070470 and 070554 and 90(Nd) varies between ndash227 and ndash355 90(Hf) values of concordant zirconscorroborate this data and range between +290 to +502 in the andesite of the first unit and from +106 to +138 in thevolcanites of the second and third unit

Keywords Late Cretaceous volcanites Chelopech petrology UndashPb zircon geochronology geochemistry

Introduction

High-sulphidation epithermal deposits are an im-portant gold resource in Eastern Europe notablyin the Bulgarian Panagyurishte region (CentralSrednogorie zone Fig 1) High-sulphidation vol-canic-hosted epithermal deposits of economicimportance such as the Chelopech major gold-copper mine (Strashimirov et al 2002 Moritz etal 2003) occur in this region The genesis of theChelopech mine the major ore producing epi-thermal deposit in this area is related to interme-diate Late Cretaceous volcanism which extrudedin the northern part of the Central Srednogoriemagmatic zone (Fig 1) The ideas about the evolu-tion of the magmatic complex changed throughtime and one (Terziev 1968 and recently Jelev etal 2003) or two (Mutafchiev 1967 Popov and

Mutafchiev 1980) to four stages of magmatic ac-tivity (Popov and Kovachev 1996) were supposedConsequently the genetic models for the forma-tion of the Chelopech deposit in relation to thevolcanic products evolved assuming one (theldquoChelopech volcanordquo) or two volcanic structures(ldquoChelopechrdquo and ldquoVozdol volcanoesrdquo) requireone or two mineralising systems respectively Forthe timing of the magmatic activity and the miner-alisation alteration products just KndashAr data areavailable (Lilov and Chipchakova 1999) whichrange from 92 to 57 Ma respectively The magma-tism in the Chelopech region was supposed to beprolonged but mainly Senonian in age

The aim of our investigation is to reconstructthe geological evolution of the Late CretaceousChelopech volcanic complex and to identify thetemporal relationships between its magmatic

S Stoykov et al102

Fig 1 (a) Major tectonic zones in Bulgaria (after Ivanov in press) with the location of the Srednogorie zone andChelopech deposit (b) Simplified geological map of the northern part of Central Srednogorie (modified afterCheshitev et al 1989) with the location of the economically important deposits Elatsite Chelopech and Medet) (c)Geological map of the Chelopech region (modified after Popov et al 2000 and Stoykov et al 2002)

Timing and magma evolution of the Chelopech volcanic complex (Bulgaria) 103

products and the mineralised zones outside of theChelopech mine An important part of the presentstudy is to trace the magmatic source determinethe precise age of volcanic units and reconstructthe magmatic processes that may contribute tothe formation of the high-sulphidation epither-mal Chelopech deposit We have combined fieldobservations with representative whole rock andmineral geochemical analyses Conventional UndashPbsingle zircon dating has been utilised to determinethe magmatic ages as this method combines therelative resistance of the zircons to hydrothermaloverprint with the high precision of the ID-TIMS(isotope dilution ndash thermal ionisation mass spec-trometry) techniques Cathode-luminescence (CL)images and Laser Ablation (LA) ICP-MS analy-ses of the zircons help the proper interpretationof the geochronological data and give evidencefor changes in the geochemistry and oxidationstate of the magma Isotope SmndashNd and RbndashSrwhole rock and Hf-zircon analyses provide addi-tional information about the magma sources andtheir evolution

Geological setting and petrology of theChelopech volcanic complex

The products of the Chelopech volcanic complexare located in the Central Srednogorie volcano-plutonic area which forms part of the Srednogo-rie tectonic zone (Dabovski et al 1991 Fig 1)The basement of the volcanic rocks consists ofSrednogorie type (Ivanov in press) high-grademetamorphic rocks (two-mica migmatites withthin intercalations of amphibolites amphibole-bi-otite and biotite gneisses) and low metamorphicphyllites and diabases of the Berkovitsa group(Early Paleozoic island-arc volcanic complex Hay-doutov 2001 Peytcheva and von Quadt 2004)These units are in tectonic contact with each otherand to the North of Chelopech the phyllites of theBerkovitsa group are intruded by the Variscangranitoids (Kamenov et al 2002) of the Vejen plu-ton The base of the Chelopech volcanic rocks ispartly exposed on the surface although it has beenintersected in the underground mine

The Late Cretaceous succession in the Chelo-pech region starts with conglomerates and coarse-grained sandstones intercalated with coal-bearinginterbeds (coal-bearing formation Moev and An-tonov 1978) covered by polymictic argilleous andarkose sandstones to siltstones (sandstone forma-tion) Collectively these units have a thickness ofless than 500 m Pollen data suggests that both for-mations are Turonian (Stoykov and Pavlishina2003) where the age of 935 Ma was taken as tran-

sitional from the Cenomanian to the Turonian ac-cording to the Geological time scale of the Geo-logical Society of America (Palmer and Geiss-man 1999) The sedimentary rocks are cut by vol-canic bodies and overlain by sedimentary and vol-canic rocks of the Chelopech Formation (Moevand Antonov 1978) It comprises the products ofthe Chelopech volcanic complex epiclastics aswell as the Vozdol sandstones (Fig 1c) The latterare recently paleontologically dated as Turonianin age (Stoykov and Pavlishina 2003) These for-mations have been eroded and transgressivelycovered by sedimentary rocks of the Upper Seno-nian Mirkovo Formation (reddish limestones andmarls) which are in turn overlain by flysch of theChugovo Formation (Campanian-Maetrichtian inage Moev and Antonov 1978) (Fig 1b c)

Based on their structures host rocks cross-cut-ting relationships and alterations on the surfacethe products of the Chelopech volcanic complexcan be subdivided into 3 units (I) dome-likevolcanic bodies (II) lava and agglomerate flowsand (III) the Vozdol volcanic breccias andvolcanics (Stoykov et al 2002 2003)

The first unit is composed of dome-like volcan-ic bodies which extruded through the unconsoli-dated Turonian sediments (the sandstone and coal-bearing formation) and through the metamorphicbasement (Fig 1c) The largest volcanic body (Mur-gana) is approximately 21 km in size It shows ahigher stage of phenocryst crystallisation than theother units Brecciated fragments of the dome-likevolcanic bodies have been observed as xenoliths inthe third unit of the Chelopech volcanic complex ndashthe Vozdol volcanic breccia

The dome-like bodies mainly have an andesit-ic and trachydacitic composition (Fig 2) They arehighly porphyritic (phenocrysts gt40 vol) Thephenocrysts consist of plagioclase zoned amphi-bole minor biotite titanite and rare corrodedquartz crystals whereas the microlites consist ofplagioclase and amphibole only The accessoryminerals are apatite zircon and Ti-magnetiteLilov and Chipchakova (1999) obtained an age of65ndash67 Ma for these bodies based on KndashAr dating

The second unit is represented by lava flowswhich grade upwards into agglomerate flows(with fragments up to approximately 30 cm insize) Borehole data sho ws that the total thick-ness of these volcanic products is generally lessthan 1200 m but exceeds more than 2000 m in theregion of the Chelopech mine (ldquowithin their ex-trusive centerrdquo Popov et al 2002) The composi-tion of the lava flows varies from latitic-trachy-dacitic to dacitic (Fig 2) Subsidiary andesites arealso present These volcanic rocks consist of thesame phenocrysts microlites and accessory min-

S Stoykov et al104

erals as the first unit with the exception of thecorroded quartz crystals The lava flows containfine-grained fully crystallised enclaves of basalticandesites to shoshonites The enclaves consist ofthe same minerals as the main mass of unit 2 (pla-gioclase amphibole and minor biotite) but com-prise phenocrysts of different (more basic) chem-istry A fine-grained quartz zone marks the mar-gins of the enclaves These features are typical formagma mingling and mixing processes and aremostly exhibited in the lava flows compared tothe other volcanic units Previous KndashAr dating ofnon-altered andesite yielded a Turonian age of 91Ma (Lilov and Chipchakova 1999)

The third unit is represented by volcanic brec-cias and volcanites that formed the so called Voz-dol monovolcano of Popov et al (2000 2002) Thevolcanic breccias contain fragments within theirlava matrix that vary in size between 20 and 80cm Brecciated fragments from the andesites ofthe first unit can be observed in outcrops in theVozdol river valley The matrix of the volcanicbody in the eastern part hosts small lenses andlayers of sedimentary material (Vozdol sand-stones) and the abundance increases towards themargins of the body The Vozdol volcanic brecciasadditionally intercalate and are covered by theVozdol sandstones (Fig 1c) The latter has paleo-ntologically been dated as Turonian in age (Stoy-kov and Pavlishina 2003) These features maysuggest that the extrusion of the third unit volcan-ites occurred contemporaneous with sedimenta-tion processes in the Turonian Based on the bore-hole data and observation in the eastern part ofthe Chelopech mine which is not in exploration atpresent Popov and Kovachev (1996) and Popov

et al (2000) conclude that the Vozdol volcanicbreccias and volcanites form the final stage of themagmatic activity in the Chelopech region cut-ting all older products of the volcanic complex aswell as the ore bodies of the Chelopech mine(Popov et al 2000) On the surface where ourwork was concentrated these relationships arenot clear In the breccias we can observe stronglyhydrothermally altered volcanic xenoliths with anobliterated primary texture which inhibited us torecognise which type was the initial volcanic rockAdditionally there are detailed studies missing onthe alteration type in these xenoliths the latterare crucial to clarify if the high-sulfidation typealteration (leading to the deposition of the gold)was genetically linked to the widespread hydro-thermal alteration along the Petrovden fault (Fig1c Popov et al 2000 Jelev et al 2003) exposed inthe Vozdol river valley Hence we can not con-clude about the possible relation of the observedxenoliths to the economic mineralisation (as itwas supposed by Jelev et al 2003)

The composition of the Vozdol volcanites var-ies from basaltic andesites and andesites to latites(Fig 2) They show similar petrographic character-istics to the older units although their phenocrysts(plagioclase amphibole minor biotite and titanite)are less abundant The groundmass is composed ofmicrolites of the same nature as minerals of thesecond unit K-feldspar is present as microlitesonly in the Vozdol andesitic rocks A biotite 40Ar39Ar age yields a Turonian age of 8995 plusmn 090 Ma(Velichkova et al 2001 Handler et al 2004)Therefore the KndashAr age of 65 Ma obtained byLilov and Chipchakova (1999) from samples at thesame locality reflects a low-temperature overprint

Fig 2 TAS diagram after Le Maitre (1989) for representative magmatic rocks from the studied region (BmdashbasaltBAmdashbasaltic andesite Amdashandesite Dmdashdacite SHmdashshoshonite Lmdashlatite TDmdashtrachydacite) DLBmdashdome-likebodies (unit 1) LAFmdashlava and agglomerate flows (unit 2) VBVmdashVozdol breccias and volcanites (unit 3)


Several dykes are exposed to the east of to theChelopech volcanic complex (outside of the mapon Fig 1c) They strike predominately in an eastndashwest direction and intrude into the Pre-upperCretaceous metamorphic basement They do notshow cross-cutting relationships to the Chelopechvolcanic complex The largest dyke is more than 7km in length These dykes have andesitic latiticdacitic and trachydacitic compositions

The magma of the volcanic complex initiallyerupted more acidic volcanic rocks The earlierproducts (dome-like bodies and lava to agglomer-ate flows) contain 61ndash64 wt SiO2 whereas themore basic Vozdol breccias and volcanites con-tained 56ndash580 wt SiO2 The cover of the Chelo-pech volcanic complex is composed of the Vozdolsandstones (in the east) muddy limestones of theMirkovo Formation (in the center) and sedimen-tary rocks of the Chelopech formation (in thewest Fig 1c)

Analytical techniques

Major and trace elements

Major and trace elements were analysed by X-rayfluorescence (XRF) at the University ofLausanne Switzerland The rare earth elements(REE) were analysed by ICP-atomic emissionspectrometry following the procedure of Voldet(1993) A petrological study has also been per-formed Mineral analyses on samples of the differ-ent units were carried out at the University ofLausanne on a CAMEBAX SX-50 electron mi-croprobe

UndashPb zircon analyses

High-precision ldquoconventionalrdquo UndashPb zircon anal-yses on single zircon grains utilised the FinniganMAT 262 thermal ionisation mass-spectrometerat ETH-Zurich using an ion counter system Se-lected zircons were air-abraded to remove mar-ginal zones with lead loss rinsed several timeswith distilled water with acetone in an ultrasonicbath and washed in warm 4 N nitric acid All sam-ples were spiked with a 235Undash205Pb mixed tracerTotal blanks were less than 0002 ng for Pb and UThe PBDAT and ISOPLOT programs of Ludwig(1988 2001) were used for calculating the uncer-tainties and correlations of UPb ratios All uncer-tainties are reported at the 2 level The decayconstants of Steiger and Jaeger (1977) were usedfor age calculations and corrections for commonPb were made using the Stacey and Kramers(1975) values

LundashHf isotope analyses

Hf isotope ratios in zircons were measured on aNu Instruments multiple collector inductivelycoupled plasma mass spectrometer (MC-ICPMSDavid et al 2001) at the Institute of Isotope Geo-chemistry and Mineral Resources ETH-ZurichTesting determined that the high Zr in the sam-

unit DLB DLB LAF LAF VBVsample No Ch 113 Ch 121 Ch 37 Ch 56 Ch 10

SiO2 6122 6057 6107 6301 5711TiO2 054 053 049 051 065Al2O3 1798 1787 1768 1636 1835Fe2O3 501 518 456 494 703MnO 014 016 013 012 012MgO 144 194 149 163 175CaO 338 445 49 491 487Na2O 532 428 421 339 419K2O 270 25 295 274 327P2O5 025 025 022 023 026LOI 173 247 154 116 155Total 9971 1002 9924 9900 9915

Nb 7 8 8 7 6Zr 121 134 126 98 127Y 23 24 24 20 18Sr 1430 904 1013 781 871Rb 72 74 67 63 46Th 4 6 3 3 3Pb 17 18 12 16 15Ga 18 18 17 19 18Zn 46 57 90 72 137Cu 25 15 10 26 35Ni 3 2 2 2 4Co 50 21 7 10 13Cr 10 10 12 14 15V 96 97 101 127 139Ba 870 778 732 1441 768S 12 3 140 113 29Hf 7 6 6 6 6Sc 6 8 10 10 9As 11 8 3 6 3La 344 n d 283 229 21Ce 668 n d 602 493 447Pr 665 n d 67 53 52Nd 301 n d 277 24 228Sm 56 n d 54 49 46Eu 141 n d 13 126 127Gd 38 n d 35 33 3Dy 35 n d 35 31 3Ho 067 n d 073 066 064Er 21 n d 2 18 17Tm 025 n d 028 026 024Yb 17 n d 17 15 14Lu 024 n d 024 022 018

Table 1 Major and trace element composition of re-presentative samples of the Chelopech volcanic com-plex DLBmdashdome like bodies (unit 1) LAFmdashlava andagglomerate flows (unit 2) VBVmdashVozdol breccias andvolcanites (unit 3)

Total Iron as Fe2O3 Major concentrations are expressedin wt and trace element concentrations in ppm re-spectively n dmdashnot detected

S Stoykov et al106Ta

ble

2U

ndashPb

zirc

on is

otop

e da

ta fo

r re

pres

enta

tive

sam

ples

of t

he th

ree

unit

s of

the

Che

lope

ch v

olca

nic

com

plex

CH

-114

mdashan

desi

te u

nit 1

CH

-56mdash

trac

hyda

cite

uni

t2

CH

-10mdash

ande

site

uni

t 3


ples did not create significant matrix effects Dur-ing analysis we obtained a 176Hf177Hf ratio for theJMC 475 standard of 0282141 plusmn 5 (1 sigma) usinga 179Hf177Hf=07325 ratio for normalisation (ex-ponential law for mass correction) For the calcu-lation of the Hf values the present-day ratios of(176Hf177Hf)CH=028286 and (176Lu177Hf)CH-=00334 were used For recalculation to 90 Ma a176Lu177Hf ratio of 00050 was taken into accountfor all zircons

RbndashSr and SmndashNd whole rock isotope analyses

The isotopic composition of Sr and Nd and thedetermination of Rb Sr Sm and Nd contentswere performed at ETH-Zurich and the Univer-sity of Geneva using ID-TIMS techniques Nd iso-topic ratios were normalised to 146Nd144Nd=07219 Analytical reproducibility was estimatedby periodically measuring the La Jolla standard(Nd) as well as the NBS 987 (Sr) The mean of 12runs during this work was 143Nd144Nd = 0511841plusmn 0000007 and 10 runs of the NBS 987 standardshow an 87Sr86Sr ratio of 0710235 plusmn 0000006 Forfurther details the reader is referred to von Quadt(1997)

Cathodoluminescence (CL) imaging

The CL-pictures were taken from a split screen ona CamScan CS 4 scanning electron microscope(SEM) at ETH Zurich The SEM is equipped withan ellipsoidal mirror located close to the samplewithin the vacuum chamber and can be adjustedby electro-motors The sample can be located inone focal point while the second focal point liesoutside the sample chamber Here the CL lightenters the highly sensitive photo multiplierthrough a quartz glass-vacuum window and a lightchannel The signal of the photo multiplier is thenused to produce the CL picture via a video-ampli-fier In general weak CL emission (dark coloursin the picture) means high amounts of minor andtrace elements strong CL emission (light coloursin the picture) means low amounts of minor andtrace elements

Laser ablation ICPMS (LA-ICPMS)

Laser ablation ICP-MS spot analyses were doneusing an Excimer laser (ArF 193 nm) with a gasmixture containing 5 fluorine in Ar with smallamounts of He and Ne connected to a PE SCIEXElan 6000 ICP-MS The sample is placed in aclosed cell together with the standard material(NIST 612) from which the ablated material iscarried out into the ICP-MS by the argon gas

stream We used a spot diameter of 40 microm The la-ser pulse repetition rate is 10 Hz The elementshave been detected with 10 ms dwell time and 3ms quadrupole settling time The measurementefficiency was around 70 Backgrounds weremeasured for 30 s and the transient signals fromthe sample material to be analysed were acquiredfor approx 30 s Calibrations for the zircon analy-ses were carried out using NIST 612 glass as anexternal standard Limits of detection are calcu-lated as 3 times the standard deviation of thebackground normalised to the volume of the sam-ple ablated (cpsmicrogg) The reproducibility of thedata during this work was estimated measuringthe NIST 612 standard For further details we re-fer to Guumlnter et al (2001)

Mineral chemistry

The composition of plagioclase phenocrysts of theMurgana dome-like body vary from An385ndash422(core) to An387ndash462 (rim) and those of the lavaflows vary from An425ndash482 (core) to An301ndash539(rim) Phenocrysts of the Vozdol breccias and vol-canites range between An508 in the center toAn362 in the periphery The rims are variable incomposition which substantially overlaps with

No 176Hf177Hf 2 error -Hf -Hf T 90 Ma

CH-101 0282759 0000006 ndash046 1033 0282764 0000003 ndash028 1204 0282769 0000003 ndash011 1385 0282760 0000002 ndash042 1066 0282752 0000002 ndash071 078


CH-11417 0282761 0000003 ndash039 11018 0282807 0000007 124 27219 0282812 0000007 141 29020 0282855 0000012 294 44221 0282872 0000010 354 502

Table 3 Hf isotope data for zircons of the Chelopechvolcanic complex (numbers as in Table 2)

During analysis the 176Hf177Hf ratio (JMC 475 stan-dard) of 0282141 plusmn 5 (1) using the 179Hf177Hf = 07325ratio for normalisation is measured For the calculation of the -Hf values the present-dayratios (176Hf177Hf)CH= 028286 and (176Lu177Hf)CH=00334 are used and for 90 Ma a 176Lu177Hf ratio of00050 for all zircons was taken into account

S Stoykov et al108

that of the phenocryst cores The composition ofplagioclase microlites varies from An48 to An31 K-feldspar microlites (Or86ndash93) were only observedin the Vozdol volcanic breccia and volcanitesAmphiboles from all the volcanic rocks displayMg between 048 and 067 and their Si per for-mula unit content ranges between 640 and 655The amphiboles plot on the limit of the magnesio-hastingsite pargasite ferropargasite hastingsiteand Fe-edenite field of Leake et al (1997) Thecomposition of the amphibole phenocrysts of themore mafic enclaves differs to those from the hostvolcanic rocks They yield higher Mg whichrange between 070 and 083 and are magnesio-hastingsites The Si per formula unit of these am-phiboles ranges between 590 and 610 (Stoykovet al 2002 2003) The large variations in Mg ofthe amphiboles combined with the reverse mine-ral zonation of the plagioclase phenocrysts reflect

processes of magma mixing and mingling that oc-curred during the evolution of the Chelopech vol-canic complex

Bulk rock trace elements composition

MORB normalised patterns for the magmaticrocks indicate an enrichment of LILE (large ionlithophile elements) and low values for HFSE(High Field Strength Element) (Ce Zr P and Hf)with a strong negative Nb anomaly as well as adepletion of the FendashMg elements (Table 1 Fig 3a)The enrichment of LILE relative to Nb is charac-teristic of crustal contamination The LREE en-richment ranges from 33 to 105 (Fig 3b) whereasLanYbn ratios vary from 10 to 13 Middle andheavy REEs show relatively flat patterns whichare generally within 5ndash30 times that of chondriteThe rocks from the Murgana dome-like body re-

Fig 3 (a) REE diagram for magmatic rocks of the Chelopech region (b) spider discrimination plot for the volcanicrocks of the Chelopech volcanic complex Data symbols as in Fig 2

a

b


veal slightly enriched values of LREEs comparedto the lava flows and the Vozdol volcanic breccia(Fig 3) An Eu anomaly is not observed whichsuggests that there was no plagioclase fractiona-tion involved during the genesis of the andesiticrocks All these features are typical for subduc-tion-related magmatic sequences Discriminationdiagrams TiO2Al2O3 vs ZrAl2O3 and ZrTiO2 vsCeP2O5 (Muumlller et al 1992) show similar compo-sition to active continental margin magmaticproducts (Fig 4)

UndashPb zircon geochronology and Hf zirconisotope geochemistry

Zircons were separated from the three differentunits of the Chelopech volcanic complex (Fig 1c)Ten zircon grains of an andesite sample CH-114from the Murgana dome-like body (unit 1) weredated (Table 2) Three of them (22 25 and 26 longprismatic beige) are plotting on the concordiawithin their uncertainties and define a mean206Pb238U age of 9222 plusmn 030 Ma (Fig 5) We inter-pret that these concordant grains most closelyrepresent the time of intrusion of the andesitebody Two of the zircon grains reveal lead loss butmost of the measured zircons have lead inherit-ance The regression line through four corre-sponding points yields an upper intercept age of467 plusmn 28 Ma indicating an Early Paleozoic event(the age of the metamorphic basement) whereasone of the analyses (No 8 Table 2) give evidence

for a possible Hercynian inheritance (the Varis-can granites of the Balkan or of the Srednogo-rie) The 90(Hf) of the zircons range from +110to +502 (Table 3) The zircon grain with the high-est apparent age (No 17 Table 2 3) shows thelowest 90(Hf) and gives evidence for upper crus-tal characteristics of the assimilated materials Onthe other hand there is no clear correlation be-tween lead inheritance and decrease of the90(Hf) values which is possibly not only due tothe fact that some grains are abraded and othersnot but more to source differences and inhomo-geneities

The UndashPb isotope systematic of the zirconfractions of a trachydacite (CH-56 Table 2) fromthe second unit shows characteristics of lead in-heritances and lead losses Four data points arealmost concordant and define a mean 206Pb238Uage of 913 plusmn 03 Ma (Fig 6) The 90(Hf) of theconcordant zircons change in a narrow range of+106 to +138 (Table 3) indicating a mixed crustaland mantle origin of the magma but more crustalinfluence compared to the andesite of the firstunit (CH-114 Table 2) The inherited old Pb com-ponents for two zircon points (Table 2 No 13 14)refer to an upper intercept ldquoVariscan agerdquo of theassimilated crustal material

Five out of seven zircon analyses of an andes-ite from the Vozdol lava breccia neck (CH-10third unit) are concordant (Fig 7 Table 2) andyield a mean 206Pb238U age of 913 plusmn 03 Ma Itcoincides within error limits with the age of thelava flow sample of the second unit Some similar

Fig 4 (a) TiO2 Al2O3 vs ZrAl2O3 and (b) ZrTiO2 vs CeP2O5 discrimination diagrams (Muumlller et al 1992) CAPmdashContinental Arc PAPmdashPostcollisional Arc IOPmdashInitial oceanic Arc LOPmdashLate oceanic Arc WIPmdashWithin-plateFor data symbols see Fig 2

S Stoykov et al110

features of both samples are revealed by the90(Hf) values of the concordant zircons changingin one and the same narrow range of +106 to+138 (Table 3 Fig 7) These similarities with closeHf-isotope characteristics is typical for both vol-canic units

Fig 5 UndashPb concordia diagram for zircons of an andesite CH-114 (Murgana dome-like body) representing the firstunit of the Chelopech volcanic complex

Fig 6 UndashPb concordia diagram for zircons of trachydacite CH-56 representing the second unit of the Chelopechvolcanic complex Solid error ellipse lines are used for the concordant zircons and dashed error ellipse lines markzircons with lead loss or lead inheritance The ndashHf data of Table 3 are plotted for the corresponding data points

CL-features and REE geochemistryof the zircons

Using cathode-luminescence (CL) images andthe Excimer Laser Ablation (LA) ICP-MS analy-ses (Table 4) we tried to characterise the inner


peculiarities and the chemistry of the zircons fromthe first to the third unit of the Chelopech volcan-ic complex which helps us to control the properinterpretation of the geochronological UndashPb zir-con data This precise study was provoked addi-tionally by recently published data of Ballard etal (2002) for calc-alkaline intrusions from theporphyry copper belt in Chile where a highCe(IV)Ce(III) ratio was characteristic for therocks with economic potential bearing magmatic-hydrothermal Cu plusmn Au It is known that this posi-

Fig 7 UndashPb concordia diagram for zircons of the andesite sample CH-10 from the Vozdol lava breccia neck repre-senting the third unit of the Chelopech volcanic complex Error ellipse symbols as in Fig 6 The ndashHf data of Table 3are plotted for the corresponding data points

tive anomaly is related to the higher oxidationstate of the parental magma that leads to oxida-tion of Ce3+ to Ce4+ the latter easily substitutesZr4+ in the lattice of zircon (Cornell and Hegardt2003) The higher oxidation state of the parentalmagma from the other side is usually considered asa prerequisite feature of the ore-producingmagmatism

The typical magmatic oscillatory zoning is ob-served in all zircon images (Fig 8) The intermedi-ate and heavy rare earth elements (REE) reveal a

Sample No CH56-C CH56-R CH10-C CH10-R CH114-C CH114-RElement

La 0149 0030 0038 2176 4273 0214Ce 2235 1933 1413 4563 1585 1551Pr 0061 0037 0033 0789 0998 0168Nd 1027 0453 0279 4752 4017 1133Sm 2701 1715 0589 4660 1059 1210Eu 1309 0800 0436 2000 0330 0878Gd 1599 9332 5288 2317 5611 9165Tb 6541 3965 2019 9676 2366 3365Dy 8482 5435 2888 1344 2884 4482Ho 3713 2438 1498 5876 1249 2043Er 1914 1344 8859 3022 6501 1148Tm 4592 3537 2440 7290 1610 2959Yb 5238 4207 3045 7994 1882 3502Lu 1163 9942 8028 1684 4186 8262

Table 4 Rare earth element contents (ppm) in zircons of the three units of theChelopech volcanic complex

Abbreviations Cmdashcore Rmdashrim

S Stoykov et al112

constant and typical magmatic (Hoskin and Ir-land 2000 Belousova et al 2002) distribution Euanomaly is not observed in the zircons which con-firms the conclusion (based on the rock chemis-

try) that there was no plagioclase fractionationduring the genesis of the andesitic magma

A recrystallised inherited zircon core is ob-served within the first unit sample CH-114 (Fig

Fig 8 Cathode-luminescent (CL) images of zircons from the three units of the Chelopech volcanic complex withthe corresponding chondrite-normalised distribution of the REE Circles on the pictures correspond to the laserablation spot in the zircon crystals


8) which is in agreement with the UndashPb datashowing inherited lead (Table 2 and Fig 5) Thechondrite-normalised pattern of the REE chan-ges in this core compared to the outer magmaticzone The striking features are specially marked inthe distribution of the light REE and the Ce posi-tive anomaly As we already calculated an Earlyand Late Paleozoic age of the inherited zirconcores we can conclude that the parental Paleozoicmagma either missed the high oxidation andorCe was released during later geological processeseg the metamorphism of the basement rocks orthe dissolution of the zircons in the Cretaceousmagma

The entire zircon of CH-56 (trachydacite ofthe second unit) as well as the zircon core part ofCH-10 (andesite of the third unit) reveal well-de-fined Ce positive anomalies marking thereforehigher oxidation state of the magma The rim partof CH-10 lost the well-pronounced positive Ceanomaly which possibly means changing of therelative oxidation state of the magma in the timewhen the zircon still crystallised (possible mixingwith a new portion of magma in the chamber)

Sr and Nd isotope geochemistry andmagma sources

The initial Sr isotope ratios of the magmatic rocksfrom the Chelopech volcanic complex and thedykes show a small range between 070470 and070554 at Cretaceous time (90 Ma correctionTable 5) Generally the initial 87Sr86Sr ratios fallwithin the field previously defined by Kouzmanovet al (2001) and von Quadt et al (2003) in therange 07046 to 07061 for Late Cretaceous magm-atites in Central Srednogorie and show similaritieswith published initial Sr values of the Apuseni-Banat-Timok-Srednogorie belt (Berza et al 1998Dupont et al 2002 von Quadt et al 2001 2003)The calculated 90(Nd) values are between ndash227and ndash355 These data together with the 90(Hf) ofthe zircons suggest a mixed mantle-crust source ofthe Turonian magmatism in the Chelopech re-gion

The (87Sr86Sr)i vs (143Nd144Nd)i diagram (Fig9) demonstrates that all data points plot close tothe enriched mantle type 1 (EM1) field which istypical for island arc volcanites Some peculiari-ties of the bulk rock chemistry and of the zirconsgive evidence for additional interaction of the en-riched mantle source magma with crustal materi-als However using the variations of the initial Srand Nd ratios vs SiO2 the evolution of the magmamay be largely due to minglingmixing processeswithout isotope homogenisation in the whole vol-N

rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114

ume of the magma chamber and not to a simpledifferentiation of one parental magma combinedor not with assimilation of upper crustal rocks

Discussion and constraints for timingand magma sources

The high-precision UndashPb zircon data demon-strate that the magmatic activity of the Chelopechregion started at the northern border with the in-trusion of the dome-like bodies at 923 plusmn 05 MaThe products of the second and the third units fol-lowed closely one after the other and they are un-distinguishable within their uncertainties UndashPbanalyses of zircons of representative samplesyield an intrusion age of 9222 plusmn 030 Ma The lavabreccias of the third unit contain fragments of thefirst unit hence the geological relationships in thefield are in agreement with isotope geochronolog-ical data The high-sulphidation epithermal CundashAu mineralisation is hosted by the volcanites ofthe second unit Assuming the error uncertaintieswe can calculate a maximum age of 916 Ma forthe epithermal deposit which coincides with therecently published data of Chambefort et al(2003) and Moritz et al (2003) The minimum ageof the deposit is still not constrained As it wasmentioned in the above chapters present investi-

gations are focussed on the special features of thevolcanic products on the surface so that we stillare not able to link the strongly altered volcanicxenoliths in the volcanic breccias of the third unitto a distinct mineralising stage

Chondrite-normalised patterns of REE andtrace elements in the zircons (LA ICP-MS analy-ses) reveal a well-pronounced positive Ce anoma-ly in the zircon grains of the second unit (trachy-dacite) and in the zircon core of the third unit (an-desite) The latter may be related to a higher oxi-dation state of the parental magma ndash a prerequi-site feature of an ore-producing magmatismThese data just show the potential of the secondunit volcanites to be the fertile phase of the vol-canic complex but are far away to prove this asthe formation of one deposit is a combination offactors which study was not the aim of the presentwork

There is commonly a close spatial relation be-tween porphyry Cu (plusmn Au) and high-sulphidationepithermal CundashAu deposits through the worldand the close temporal relation between themshould be an argument for their genetic link (Ar-ribas et al 1995) The world-class porphyry Cudeposit Elatsite is located about 6 km to the NNWof the Chelopech high-sulphidation epithermalCundashAu deposit and a genetic link between themwas proposed by Popov et al (2002) The ore-pro-

Fig 9 (87Sr86Sr)i vs (143Nd144Nd)i diagram for rock samples of Chelopech volcanic complex Fields of the DMM(depleted MORB mantle) HIMU (magma source having a high -238U204Pb ratio) EM1 and 2 (enriched mantle 1and 2) and BSE (bulk silicate earth) are given (corrected for 90 Ma) according to Zindler and Hart (1986) and Hartand Zindler (1989) Dashed lines correspond to the Sr and Nd isotope values of the undifferentiated reservoir ndashidentical to CHUR (DePaolo 1988 Faure 2001) corrected for 90 Ma For data symbols see Fig 2


ducing magmatism in Elatsite was bracketed inthe time span 921 plusmn 03 Ma to 9184 plusmn 031 Mausing high-precise UndashPb zircon dating (vonQuadt et al 2002) and confirmed later by RendashOsmolybdenite age determinations in the range of931ndash923 Ma (Zimmermann et al 2003) For anon-productive dyke of the deposit von Quadt etal (2002) obtained a mean 206Pb238U age of 9142plusmn 015 Compared with the present data of theChelopech volcanic complex there is an overlapbetween the ore-producing magmatism in Elat-site and the dome-like andesitic bodies The finalbarren stage of the magmatism in Elatsite was al-most contemporaneous with the volcanic rocksthat host the Chelopech deposit The age data donot discard therefore the model of a commonmagmatic chamber for both deposits with somepulses of intrusionextrusion of magmatites Un-fortunately we did not observed the publisheddata about structures between the Chelopech andthe Elatsite deposits which could explain the hori-zontal distance of about 6 km and the vertical dis-placement of about 1 km Therefore present iso-tope-geochronological data are not enough to fa-vour the idea for one and the same magmatic-hy-drothermal system for both deposits

The petrological and geochemical featuresgive additional evidence for a possible uniformmagma chamber of the volcanic rocks in theChelopech and Elatsite deposits with a complexevolution in Turonian times when a combinationof processes of magmatic differentiation assimi-lation mingling and mixing took place The mag-matic products in Elatsite and Chelopech revealsimilar Sr Nd and Hf characteristics where thetendency of an increase of 90(Nd) and a decreaseof 90(Hf) zircon could be related to minor assimi-lation of host rocks within parts of the magmaticchamber The amphibole chemistry of the mag-matic units of both deposits shows some similarcharacteristics ndash Mg between 048 and 067 andSi per formula unit content between 640 and 655but mark differences comparing to the other de-posits of the Panagyurishte ore region (Kamenovet al 2003)

Conclusions

The combined petrologic isotope-geochemicaland geochronological investigations of the Chelo-pech volcanic complex suggest

ndash The three units of the Chelopech volcaniccomplex are separated on the basis of their struc-tural textural petrographical and geochemicalcharacteristics including the chemistry of the phe-nocrysts

ndash the magmatic activity proceeded in Turoniantime starting with the intrusion of the dome-likebodies at 922 plusmn 03 Ma and finishing with the for-mation of the Vozdol breccias and volcanites at913 plusmn 03 Ma

ndash Nd and Sr whole rock and Hf-zircon charac-teristics argue for mixed crustal-mantle origin ofthe magma for all three volcanic units

ndash the evolution of the magmatism was definedby processes of magma mingling and mixing dif-ferentiation and assimilation of crustal rocks

ndash a maximum age of 916 Ma of the ChelopechCu-Au deposit could be calculated based on thedating of the second unit volcanites hosting theeconomic mineralisation the positive Ce anomalyin zircon from the same unit gives evidence forthe high oxidation state of the magma

ndash additional studies on the relationships of thevolcanic units to the economic mineralisation andaltered rocks as well as detailed tectonic investi-gations will help to constrain the age of the Chelo-pech deposit and to create reasonable models ofits formation or possible link to adjacent deposits

Acknowledgements

This work was supported by the Swiss National ScienceFoundation through the SCOPES Joint ResearchProjects 7BUPJ062276 and 7BUPJ62396 and researchgrant 21-5904199 Present study is a contribution to theABCD-GEODE (Geodynamics and Ore DepositsEvolution of the Alpine-Balkan-Carpathian-DinarideProvince) research program supported by the EuropeanScience Foundation The authors would like to thankthe geological staff of the Chelopech mine for their helpduring the visits of the deposit Z Cherneva and M Po-pov are kindly acknowledged for the help in samplepreparation and the zircon separation and P Voldet(University of Geneva) for REE whole rock data acqui-sition R Spikings is thanked for the corrections of theEnglish The authors are grateful to the two reviewersW Halter and J Lexa and the guest-editors of the spe-cial SMPM issue for their constructive suggestions andcorrections that helped to improve the manuscript

References

Arribas A Hedenquist Jr Itaya JW Okada T Con-cepcion RA and Garcia JS (1995) Contempora-neous formation of adjacent porphyry and epither-mal Cu-Au deposits over 300 ka in northern LuzonPhillippines Geology 23 337ndash340

Ballard JR Palin MJ and Campbell JH (2002) Rela-tive oxidation states of magmas inferred fromCe(IV)Ce(III) in zircon application to porphyrycopper deposits of Northern Chile Contrib MineralPetrol 144 347ndash364

Belousova E Griffin W OrsquoReilly S and Fisher N(2002) Igneous zircon trace element composition asan indicator of source rock type Contrib MineralPetrol 143 602ndash622

Berza T Constantinescu E and Vlad S-E (1998) Up-per Cretaceous magmatic series and associated min-eralisation in the Carpathian-Balkan orogen Re-source Geology 484 291ndash306

S Stoykov et al116

Cheshitev G Kanchev I Valkov V Marinova RShiljafova J Russeva M and Iliev K (1989) Geo-logical map of Bulgaria scale 1500000

Chambefort I von Quadt A and Moritz R (2003)Volcanic environment and geochronology of theChelopech high-sulfidation epithermal deposit Bul-garia regional relationship with associated depositGeoph Research Abstr 5 00569 (CD version)

Cornell DH and Hegardt EA (2003) No more blinddates with zircon Geoph Research Abstr 5 02524(CD version)

Dabovski Ch Harkovska A Kamenov B Mavrud-chiev B Stanisheva-Vasileva G and Yanev Y (1991)A geodynamic model of the Alpine magmatism inBulgaria Geol Balcanica 214 3ndash15

Dabovski C Boyanov I Khrischev Kh Nikolov TSapunov I Yanev Y and Zagorchev I (2002)Structure and Alpine evolution of Bulgaria GeolBalcanica 322ndash4 9ndash15

David K Frank M OrsquoNions RK Belshaw NS andArden JW (2001) The Hf isotope composition ofglobal seawater and the evolution of Hf isotopes inthe deep Pacific Ocean from FendashMn crusts ChemGeol 178 23ndash42

DePaolo DJ (1988) Neodymium isotope geochemistrySpringer Verlag Berlin 187 pp

Dupont A Vander Auwera J Pin C Marincea S andBerza T (2002) Trace element and isotope (Sr Nd)geochemistry of porphyry- and scarn-mineralisingLate Cretaceous intrusions in Banat western SouthCarpathians Romania Mineralium Deposita 376ndash7568ndash586

Faure G (2001) Origin of igneous rocks the isotopicevidence Springer Verlag Berlin 496 pp

Guumlnther D von Quadt A Wirz R Cousin H andDietrich V (2001) Elemental analyses using LaserAblation-Inductively Coupled Plasma-Mass Spec-trometry (LA-ICP-MS) of Geological samples fusedwith Li2B4O7 and calibrated without matrix-matchedstandards Mikrochimica Acta 136 101ndash107

Handler R Neubauer F Velichkova S and Ivanov Z(2004) 40Ar39Ar age constraints on the timing ofmagmatism and post-magmatic cooling in the Pana-gyurishte region Bulgaria Schweiz Mineral Petro-gr Mitt 84 119ndash132

Hart SR and Zindler A (1989) Constraints on the na-ture and development of chemical heterogeneitiesin the mantle In Peltier WR (ed) Mantle convec-tion Gordon and Breach Science Publishers NewYork 261ndash382

Haydoutov I (2001) The Balkan island-arc associationin West Bulgaria Geol Balcanica 311ndash2 109ndash110

Hoskin P and Irland T (2000) Rare earth chemistry ofzircon and its use as a provenance indicator Geo-logy 287 627ndash630

Ivanov Z (2002) Tectonics of Bulgaria (in press)Kouzmanov K Moritz R Chiaradia M and Ramboz

C (2001) Sr and Pb isotope study of AundashCu epither-mal and porphyry-Cu deposits from the southernpart of the Panagyurishte district Sredna Gora zoneBulgaria In Piestrzynski et al (eds) Mineral De-posits at the Beginning of the 21st Century Swets ampZeitlinger Publishers Lisse 539ndash542

Kamenov B von Quadt A and Peytcheva I (2002)New insight into petrology geochemistry and datingof the Vejen pluton Bulgaria Geochem MineralPetrol 39 3ndash25

Kamenov B K Nedialkov R Yanev Y and Stoykov S(2003) Petrology of Late Cretaceous ore-magmaticcenters from Central Srednogorie Bulgaria InBogdanov K and Strashimirov S (eds) Cretaceousporphyry-epithermal systems of the Srednogorie

zone Bulgaria Society of Economic GeologistsGuidebook Series 36 133 pp

Leake BE Woolley AR Arps CES Birch WDGilbert MC Grice JD Hawthorne FC Kato AKisch HJ Krivovichev VG Linthout K Laird JMandariano J Maresch WV Nickel EH RockNMS Schumacher JC Smith DC StephensonNCN Ungaretti L Whittaker EJW and YouzhiG (1997) Nomenclature of amphiboles Report ofthe Subcommittee on amphiboles in the IMAC onnew minerals and minerals names Eur J Mineral 9623ndash651

Le Maitre RW (1989) A Classification of igneousrocks and glossary of terms Oxford Blackwell SciPubl 193 pp

Lilov P and Chipchakova S (1999) KndashAr dating of theLate Cretaceous magmatic rocks and hydrothermalmetasomatic rocks from Central Srednogorie Geo-chem Mineral Petrol Sofia 36 77ndash91 (in Bulgarianwith English abstract)

Ludwig KR (1988) PBDAT for MS-DOS a computerprogram for IBM-PC compatibles for processingraw PbndashUndashTh isotope data version 100a US Geo-logical Survey Reston VA United States 37 pp

Ludwig KR (2001) IsoplotEx ndash A GeochronologicalToolkit for Microsoft Excel Berkeley Geochrono-logical Center Special Publication No 1a 43 pp

Moev M and Antonov M (1978) Stratigraphy of theUpper Cretaceous in the eastern part of Strelcha ndashChelopech line Ann de llsquoEacutecole sup mines et geacuteol23 Fasc II Geacuteol 7ndash27 (in Bulgarian with Englishabstract)

Moritz R Jacquat S Chambefort I Fontignie DPetrunov R Georgieva S von Quadt A (2003)Controls on ore formation at the high-sulphidationAundashCu Chelopech deposit Bulgaria evidencefrom infrared fluid inclusion microthermometry ofenargite and isotope systematics of barite InEliopoulos et al (eds) Mineral exploration andsustainable development Millpress Rotterdam1173ndash1176

Muumlller D Rock NMS and Groves DI (1992) Geo-chemical descrimination between shoshonitic andpotassic volcanic rocks in different tectonic setting apilot study Mineral Petrol 46 259ndash289

Palmer A and Geissman J (1999) 1999 Geologicaltime scale Geol Soc of America Product codeCTS004

Peytcheva I and von Quadt A (2004) The Palaeozoicprotoliths of Central Srednogorie Bulgaria recordsin zircons from basement rocks and Cretaceousmagmatites Proceed 5th Intern Symp on EasternMediterran Geol 14ndash20042004 ThessalonikiGreece Vol 1 392ndash395

Popov P and Kovachev V (1996) Geology compositionand genesis of the Mineralizations in the Centraland Southern part of the Elatsite-Chelopech orefield In P Popov (ed) Plate Tectonic Aspects of theAlpine Metallogeny in the Carpato-Balkan regionUNESKO-IGCP Project No 356 Proccedings of theannual meeting Sofia 1 159ndash170

Popov P Petrunov R Strashimirov S and KanazirskiM (2000) Elatsite ndash Chelopech ore field In Guideto Excursions A and C of ABCD-GEODE 2000Workshop Sofia 8ndash18

Popov P Radichev R and Dimovski S (2002) Geologyand evolution of the Elatzite-Chelopech porphyry-copper ndash massive sulfide ore field Ann Univ Miningand Geol 43ndash441 31ndash44

Stacey JS and Kramers JD (1975) Approximation ofterrestrial lead isotope evolution by a two-stagemodel Earth Planet Sci Lett 26 207ndash221


Steiger RH and Jaumlger E (1977) Subcommission ongeochronology Convention on the use of decay con-stants in geo- and cosmochronology Earth PlanetSci Lett 36 359ndash362

Stoykov S Yanev Y Moritz R and Katona I (2002)Geological structure and petrology of the Late Cre-taceous Chelopech volcano Srednogorie magmaticzone Geochem Mineral Petrol 39 27ndash38

Stoykov S Yanev Y Moritz R and Fontignie D(2003) Petrology Sr and Nd isotope signature of theLate Cretaceous magmatism in the South-easternpart of Etropole Stara planina Srednogorie mag-matic zone Ann Univ Mining and Geol 461 201ndash207

Stoykov S and Pavlishina P (2003) New data for Turo-nian age of the sedimentary and volcanic successionin the southeastern part of Etropole Stara PlaninaMountain Bulgaria C R Acad bulg Sci 566 55ndash60

Strashimiriov S Ptrunov R and Kanazirski M (2002)Porphyry-copper mineralization in the central Sred-nogorie zone Mineralium Deposita 37 587ndash598

Velichkova S Handler R Neubauer F and Ivanov J(2001) Preliminary 40Ar39Ar mineral ages from theCentral Srednogorie Zone Bulgaria Implication forthe Cretaceous geodynamics In ABCD GEODEworkshop Vata Bai Romanian Journal of Mineraldeposits 79 2 112ndash113

Voldet P (1993) From neutron activation to inductivelycoupled plasma-atomic emission spectrometry inthe determination of rare-earth elements in rocksTrends in Analytical Chemistry 12 8ndash15

von Quadt A Ivanov J and Peytcheva I (2001) TheCentral Srednogorie (Bulgaria) part of the Cu (AundashMo) belt of Europe A review of the geochronologi-cal models in the light of the new structural and iso-topic studies In Piestrzyski LA (ed) Mineral de-posits at the Beginning of the 21st Century Swets ampZeitlinger Publishers Lisse 555ndash558

von Quadt A Peytcheva I Kamenov B Fanger LHeinrich CA and Frank M (2002) The Elatsiteporphyry copper deposit in the Panagyurishte oredistrict Srednogorie zone Bulgaria UndashPb zircongeochronology and isotope-geochemical investiga-tions of magmatism and ore genesis In BlundellDJ Neubauer F and von Quadt A (eds) The Tim-ing and Location of Major Ore Deposits in anEvolving Orogen Geol Soc London Spec Publ204 119ndash135

von Quadt A Peytcheva I and Cvetkovic V (2003)Geochronology geochemistry and isotope tracing ofthe Cretaceous magmatism of East-Serbia andPanagyurishte district (Bulgaria) as part of theApuseni-Timok-Srednogorie metallogenic belt inEastern Europe In Eliopoulos DG et al (eds)Mineral Exploration and Sustainable DevelopmentMillpress Rotterdam 1 407ndash410

Zimmerman A Stein H Markey R Fanger L Hein-rich C von Quadt A and Peytcheva I (2003) RendashOs ages for the Elatsite CundashAu deposit Srednogoriezone Bulgaria In Eliopoulos et al (eds) Mineralexploration and sustainable development MillpressRotterdam 1253ndash1256

Zindler A and Hart SR (1986) Chemical geodynam-ics Ann Rev Earth Planet Sci 14 493ndash571

Received 26 January 2004Accepted in revised form 30 August 2004Editorial handling T Driesner

S Stoykov et al102

Fig 1 (a) Major tectonic zones in Bulgaria (after Ivanov in press) with the location of the Srednogorie zone andChelopech deposit (b) Simplified geological map of the northern part of Central Srednogorie (modified afterCheshitev et al 1989) with the location of the economically important deposits Elatsite Chelopech and Medet) (c)Geological map of the Chelopech region (modified after Popov et al 2000 and Stoykov et al 2002)











S Stoykov et al104






















ble

2U

ndashPb

zirc

on is

otop

e da

ta fo

r re

pres

enta

tive

sam

ples

of t

he th

ree

unit

s of

the

Che

lope

ch v

olca

nic

com

plex

CH

-114

mdashan

desi

te u

nit 1

CH

-56mdash

trac

hyda

cite

uni

t2

CH

-10mdash

ande

site

uni

t 3










Mineral chemistry





CH-11417 0282761 0000003 ndash039 11018 0282807 0000007 124 27219 0282812 0000007 141 29020 0282855 0000012 294 44221 0282872 0000010 354 502



S Stoykov et al108






a

b









S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116


























































S Stoykov et al104






















ble

2U

ndashPb

zirc

on is

otop

e da

ta fo

r re

pres

enta

tive

sam

ples

of t

he th

ree

unit

s of

the

Che

lope

ch v

olca

nic

com

plex

CH

-114

mdashan

desi

te u

nit 1

CH

-56mdash

trac

hyda

cite

uni

t2

CH

-10mdash

ande

site

uni

t 3










Mineral chemistry





CH-11417 0282761 0000003 ndash039 11018 0282807 0000007 124 27219 0282812 0000007 141 29020 0282855 0000012 294 44221 0282872 0000010 354 502



S Stoykov et al108






a

b









S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116
































































ble

2U

ndashPb

zirc

on is

otop

e da

ta fo

r re

pres

enta

tive

sam

ples

of t

he th

ree

unit

s of

the

Che

lope

ch v

olca

nic

com

plex

CH

-114

mdashan

desi

te u

nit 1

CH

-56mdash

trac

hyda

cite

uni

t2

CH

-10mdash

ande

site

uni

t 3










Mineral chemistry





CH-11417 0282761 0000003 ndash039 11018 0282807 0000007 124 27219 0282812 0000007 141 29020 0282855 0000012 294 44221 0282872 0000010 354 502



S Stoykov et al108






a

b









S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116

























































Mineral chemistry





CH-11417 0282761 0000003 ndash039 11018 0282807 0000007 124 27219 0282812 0000007 141 29020 0282855 0000012 294 44221 0282872 0000010 354 502



S Stoykov et al108






a

b









S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116
















































S Stoykov et al108






a

b









S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116
























































S Stoykov et al110















S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116

























































S Stoykov et al112











rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116






















































rro

ck ty

peun

itR

bSr

87R

b86

Sr87

Sr86

Sr2

(87Sr

86Sr

) i90

SmN

d14

7 Sm

144 N

d143 N

d14

4 Nd

2(14

3 Nd

144 N

d)-

Nd

(ppm

)(p

pm)

erro

r(p

pm)

(ppm

)er

ror

T=

90T

= 9

0

56tr

achy

daci

te2

118

905

037

830

7051

870

0000

220

7047

032

4114

63

009

920

5124

640

0000

420

5124

06ndash2

27

81an

desi

te1

9969

50

4114

070

5750

000

0027

070

5224

315

170

10

1117

051

2444

000

0013

051

2378

ndash28

111

4an

desi

te1

209

925

065

390

7056

860

0000

370

7048

503

0115

85

011

470

5124

450

0000

690

5123

77ndash2

82

37i

ande

site

enc

lave

235

403

025

340

7055

190

0000

160

7051

954

3520

72

012

680

5124

250

0000

220

5123

50ndash3

35

10an

desi

te3

4687

10

1480

070

5133

000

0007

070

4944

460

228

00

2018

051

2459

000

0001

051

2340

ndash35

524

lati

te1

7262

30

3230

070

5845

000

0007

070

5432

560

390

00

1436

051

2457

000

0009

051

2372

ndash29

237

daci

te2

6710

130

0660

070

5620

000

0001

070

5536

540

277

00

1960

051

2460

000

0007

051

2345

ndash34

6

Tabl

e5

Rbndash

Sr a

nd S

mndashN

d is

otop

e da

ta fo

r w

hole

roc

k sa

mpl

es o

f the

Che

lope

ch v

olca

nic

com

plex

S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116
















































S Stoykov et al114











Conclusions








Acknowledgements


References





S Stoykov et al116



















































Conclusions








Acknowledgements


References





S Stoykov et al116
















































S Stoykov et al116
















































Timing and magma evolution of the Chelopech volcanic ... · Timing and magma evolution of the...

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Transcript of Timing and magma evolution of the Chelopech volcanic ... · Timing and magma evolution of the...