Geoffrey Ruiz Contracted by GeoLogin 3G: Geologin 3G CCSC · CCSC 87-6700 Rumble street, Burnaby,...

Geoffrey Ruiz, GeoLogin 3G, madeleine 28, 1800 Vevey, Switzerland. Tel.: +41 78 847 43 68, email: [email protected], http://www.geologin3g.com

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Geoffrey Ruiz Geologin 3G Madeleine 28 1800 Vevey Switzerland Tel: +41 78 847 43 68 [email protected] http://www.geologin3g.com

Contracted by GeoLogin 3G: CCSC 87-6700 Rumble street, Burnaby, V5E4H7, BC, Canada Tel: + 1 778 986 10 26 (Canada) Fax + 1 604 777 07 23 Mobile + 49 176 61 28 31 05 (Germany) + 99 455 234 83 36 (Azerbaijan) www.caspiancsc.com

Lausanne 17th of January 2014 “Oil and gas prospects: insights from low-temperature thermal modelling and peak temperature maturity for shales”. Dear Madam, Sir In 2011, Geo Login 3G in cooperation with Caspian Consultancy Service Company (CCSC) set up a joint partnership to provide full consultancy services to Oil, Gas and Energy industry in Geology, Geochemistry, Geophysics and Geomechanics. Our Directors are graduates at doctorate level from ETH Zurich or IPG Paris and Azerbaijan Oil Academy. The group also includes a number of experts in structural geology with geochemical, geohazards (seismotectonics), seismology, sedimentology and geophysics (geomodelling, ArcGis, 3Dmove) experience. We have experience in different and challenging regions such as the Amazon Basin, Northern Africa, the Eastern Cordillera of Ecuador and Peru, Zagros (Iran), Azerbaijan, the Alps, and Caucasus. Moreover, I am also a reviewer and editor of peer viewed international journals in Earth Sciences. The attached pamphlet presents the expertise of the geologists who have been involved in oil and gas prospection during the last 15-10 years. In addition, we utilise an analytical approach that constrains the maturity of carbonaceous rich shales (graphitization), a non-reversible process, which records maximum peak temperatures. This approach can be used to trace shale gas from outcrop or well and subsequently extrapolate to the basin.


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Figure 1: Sampling approach used by GeoLogin 3G to trace cooling and heating patterns within the oil and gas temperature window using 4 low-temperature-thermochronology methods (left). The methods are apatite (U-Th)/He, (AHe); apatite fission track, (AFT); zircon (U-Th)/He, ZHe; and zircon fission track (ZFT). Circles 1 are conventional & direct approaches whereas circles 2 are either indirect and/or unconventional approaches. The end product is to identify phases of cooling and heating within the O&G temperature window in the basins (and orogen). 1) The oil and gas temperature window range within the bounds described by the thermochronometers mentioned in figure 1. Thermal modelling is rigorous within the 120 and 55°C isotherms with additional constraints that are a near-surface presence for the Aptian-Albian and/or additional low-temperature ages outside the 120-55°C bounds (Fig. 2). Such thermal models 1) yield time-temperature, or exhumation-burial paths of sedimentary sequences in the basin, 2) the residence time for sedimentary sequences within the oil & gas window and 3) phases of uplift in the basins and orogens (Fig. 2).

Figure 2: Temperature-time models for substratum of the Cretaceous Andean Amazon Basin. The substratum is in unconformable contact (60 my hiatus) with the overlying reservoir (Aptian-Albian Hollin). 1, 2, 3, 4 are the four low-temperature thermochronometers: AFT, ZFT, AHe, ZHe, 2) In addition, we utilise an analytical approach that constrains the maturity of carbonaceous rich shales (graphitization), a non-reversible process, which records maximum peak temperatures. This approach can be used to trace shale gas from outcrop or well and subsequently extrapolate to the basin.

GeoLogin 3G proposes for Oil & Gas prospecting purposes to: - Generate thermal modelling within the oil and gas window in the hinterland and surrounding clastic basins thanks to bedrock and well/core samples - Determine the residence time of a sedimentary level within the oil & gas window (new) - Prospect shale maturity and shale gas (new) - Date fault gouge and quantify differential movements across fault systems (new) - Date fault and fold propagation (new) - Identify and quantify denudation and deposition in the basin with (rapid) tools we developed (new) - Determine illite crystallinity, geochemical and mineralogical analyses, characterization of organic material (Rock Eval, Raman Spectroscopy)


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Our company is at the cross-roads of many centres of excellence in Geosciences in Switzerland, e.g. ETH Zurich, University Bern, University Lausanne, University Geneva and University Fribourg. We have agreements with all laboratories for an access to their facilities. If needed – for a rapid turn around, we can speed up the acquisition using our secondary laboratory networks (Denmark, United Kingdom, France, USA, Spain and New Zealand). We are taking a different approach to normal consulting procedures in that interpretation of your analyses will be done with you on a one per one personal basis - we will interpret the small and large-scale dataset(s) for you, with you – as true collaborators. We believe that these analyses will add great value potential in any prospects studies to achieve scientific and economical advancements in oil and gas industry. With our kind regards Geoffrey Ruiz (owner)


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Applications and implications of combined low-temperature thermochronological, geometer analyses and geological observations for

- the identification and quantification of thermal changes in a basin-orogen system - oil & gas prospect

GeoLogin 3G consultants


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1. Introduction 6

2. Applications & implications for oil & gas prospect 7 2.1. “Direct” thermochronology 7

2.1.1. Thermal modelling in a basin – Oil and Gas prospect (Amazon basin) 7

2.1.2. Differential exhumation across fault systems. 10

2.1.3. Fault gouge/sealing dating. 11

2.1.4. Changes in exhumation rates compared to sedimentation rates (Amazon) 12

2.1.5. Inversion of the Western High-Atlas, thrust propagation 14 2.1.6. Determination of Peak Temperature and its age, shale gas 15

2.2. Indirect or Detrital thermochronology 17

3. Methods

Low-Temperature thermochronology 18

- Definitions - The different thermochronometers - Resetting - Thermal modelling Peak Temperature maturity 20

4. Conclusions 21

5. Modus operandi 22


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1. Introduction You will find later in the methodology section some brief descriptions and definitions on low-temperature methods with accurate references if you wish to go deeper into the geochemistry of these methods. In the second section is described the potential of these methods in any geological context. I illustrate all this with some examples from our previous studies in different orogens-basin systems (Andes, Amazon, Zagros, Atlas, Alps, Caucasus, South Africa, Tunisia, Balkans). Since 12 years we have used low-temperature thermochronology to quantify vertical movements within the upper 10 kilometres of the crust. The low-temperature thermochronometre with the lowest temperature of closure (U-Th-Sm/He on apatite Fig. 1) investigates the most recent geodynamical evolution and this is logical that this is the reverse with the one with the highest temperature of closure (Zircon Fission-Track, Fig. 1). Here is a brief list of what is detailed in section 2 1) A direct thermochronological approach permits

- Thermal modelling of basin fill series and hence determines residence time within the oil and gas rich shale temperature windows. - More recently, I combined Raman Spectroscopy (“graphitization”) to low-temperature thermochronology analyses. This approach is in development but it has a high potential for gas and oil prospect (see below). - With colleagues of the University of Grenoble (France) and Lausanne (Switzerland) we are dating fault gouge using Ar/Ar thermochronology on authigenic illite and microprobe analyses to determine the temperature of equilibrium for phyllosilicates, chlorite, mica and smectite. - To point active faulting, its age and to quantify differential movements across faults, and finally fault and fold propagation. - Vertical sampling (in the orogen but also from wells) allows identification of changes in denudation in the hinterland and basin

2) Indirect or detrital (on the sediments) analyses on past and present-erosion products of the orogen that allows past and recent denudation to be traced in the hinterland Some of the applications for low-temperature thermochronology are of major interest for hydrocarbon industry because they fill a void of data from the “source” towards the sink aspect. The potential of our approach is important for oil and gas industry because it is based on the combination of knowledge in isotope geochemistry, structural geology, sedimentology, but also geomorphology. It necessitates a perfect comprehension of low-thermochronological methods, their limits, fields of application and some innovation.


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2. Applications and implications for oil & gas prospect

Figure 3 (id. Fig. 1). Sampling approach used by GeoLogin 3G to trace vertical movements using low-temperature-thermochronology methods. Circles 1 are conventional & direct approaches whereas circles 2 are either indirect and/or unconventional approaches. The end product is to identify and quantify vertical movements anywhere and at any time using rates of cooling or heating. Temperatures of closure and/or partial annealing zone see section 3. There are two ways to tackle vertical movements in orogen-basin settings, the 'direct' and the 'indirect' or detrital approaches (Fig. 3). The first one aims to 'directly' constrain vertical movements from bedrocks of the orogens and basins through low-temperature thermochronology on both apatite and zircon minerals. These methods allow an immediate inspection of vertical movements for the upper crust. Examples discussed below arise from past projects. With a multiple approach, it is possible to investigate the short and long-term phases of orogenic growth, and burial in the basin. ‘Indirect’-detrital thermochronology is based on the fact that the denudation record of the orogen is systematically deposited into the adjacent basins. Such approach is implemented, when a direct approach is impossible on the basin fill series and even present-day erosion products (sands). It traces denudation records that are no longer present in the orogen since erosion has often removed the record of earlier stages. A sediment can be fully reset and as a result be modelled (direct approach).

2.1. Direct thermochronology

2.1.1. Thermal modelling in a basin – Oil and Gas prospect The Andean Amazon basin of Ecuador is a perfect example to illustrate how it is possible to constrain the thermal history of a basin and hence investigate its oil & gas potentials (Fig. 4). Oil is encountered in the Cretaceous basin of the Andean Amazon basin of Ecuador and source rocks vary in the Andean Amazon Basin: they can be Palaeozoic formations and black shales from the Middle Cretaceous. Reservoir rocks vary as well ranging from early Cretaceous to Eocene sandstones.


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Figure 4: Geological map of the Eastern Cordillera (EC) and Sub-Andean Zone (SAZ) of northern Ecuador (modified from Litherland et al., 1994). Basin fill encompass the Aptian-Albian Hollin Fm. to the Quaternary. Substratum formations and units are indicated, i.e. the Misahualli Fm., Abitagua Batholith, Pumbuiza Fm. and Paradalarga Unit. Above is indicated the position of cross-section of Figure 6. SF, CF, AF, SAF, QF, RF, CH: Subandean Fault, Cosanga Fault, Abitagua Fault, Sub-Andean Front, Quijos Fault and Reventador Fault, Cordillera de Huacamoyos. We sampled the complete Jurassic to present-day basin fill series in the Sub-Andean Zone. None yielded any apatite, with the exception of Jurassic volcanics but many zircons because apatite crystals are fragile and the depositional environments were of too high energy. This 1) eluded AFT and AHe analyses and as a result time-temperature modelling of the post-Cretaceous series themselves and 2) forced to develop a novel approach in detrital thermochronology (see above and 4). However, we found an alternative. The Jurassic substratum and the Hollin Fm. are in unconformable contact in the Sub-Andean Zone (Fig. 5). Hence they underwent a common thermal history since the Aptian-Albian. Exact phases of heating, and cooling are identified thanks to thermal modelling using input parameters that are Fission-Track and U-Th-Sm/He analyses + some external constraints, i.e. geology (unconformity) and timing (other low-temperature thermochronometers) – figure 5. Finally time of residence in the oil and gas window temperature can be estimated. Heating and cooling phases are interpreted as phases of burial and exhumation using a geothermal gradient. All these discoveries are later utilised to constrain oil and gas generation.


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We can observe different phases from left to right that are: 1) The eruption of the volcanics that began in the early Jurassic. 2) A phase of burial that was related to the deposition of volcanics and volcano-sediments still from the Jurassic volcanic arc 3) A phase of exhumation that was concomitant with the end of arc activity and related to the accretion of a terrane along the Ecuadorian margin to the west. This phase most likely generated the hiatus we dated. 4) A phase of burial that correspond to the development of a Cretaceous to Late Eocene back-arc basin. 5) An ultimate phase of exhumation associated to oil migration in the Oligocene-early Miocene generating the Sub-Andean Zone

Figure 5: Inverse thermal modelling for substratum of the Cretaceous Andean Amazon basin within the 120-55°C bounds that correspond to the partial annealing zones of the (U-Th)/He and Fission-Track systems on apatite. AHe & ZHe: U-Th-Sm/He analyses on apatite and zircon. AFT and ZFT. fission-track on apatite and zircon Thick black lines: constrained paths. Dashed black lined represents unconstrained paths but uses the local geological (unconformity) and additional thermochronometric constraints. The substratum is composed of early Jurassic volcanics that are in unconformable (60 my hiatus) contact with the overlying sedimentary reservoir Hollin Fm of Aptian-Albian age. AFT and ZFT ages range between 180-175 Ma. The Hollin Fm. is composed of a succession of cross-bedded sandstones with some conglomerates. Black: oil-bitumen dripping from the sandstones. Because the maximum burial temperature was reached before the ultimate phase of cooling towards the surface cooling (Fig. 5) it is possible to estimate the missing sedimentary pile above this outcrop. We use a geothermal gradient ranging between 25 and 20°C/km, a temperature difference of 50°C between the maximum temperature reached of 70°C and a surface temperature of 20°C: 50°C/22°/km= 2.2 kilometres. Such value is in agreement with 1) reported stratigraphic thickness from a nearby well drilled by Petro-Ecuador and 2) values from the proximal Amazon basin. Conclusion: The thermal modelling of the substratum of any basin can be completed using bedrock and/or core sample to determine with precision the thermal history but also the time of residency of source rocks within the 120-55°C temperature window. Such temperatures correspond to the temperature range of the maturation of organic material. NB: substratum does not always


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imply crystalline, volcanics or metamorphics, it can be a sedimentary formation that has been fully reset to temperatures higher than its metastable zone (section 3).

2.1.2. Differential exhumation across fault systems. Samples from the Sub-Andean Thrust Belt are located between the Subandean Fault and Cosanga Fault (Fig. 6). They are 1) volcano-sediments of Jurassic age, and 2) Jurassic pelites (Ju). AFT and ZFT ages from the SATB yielded similar ages to those from the Eastern Cordillera ranging between 6.4 and 2.4 Ma, and 55-45 Ma respectively. East of the Cosanga Fault AFT and ZFT ages are much older and can reach 180 Ma (Fig. 6) as illustrated with the sample modelled in figure 5.

Figure 6: Cosanga section (see Fig. 4 for location) with both apatite and zircon fission-track ages, respectively AFT and ZFT. Thin black line: topography. Left-axis: altitude in meters. Right-axis: age (Ma). X-axis: distance in kilometres. Light grey background: the Eastern Cordillera. Darker grey background: extension of the Eastern Cordillera proposed in this text according to the numerous new thermochronological data. Lighter grey with white crosses correspond to an Early Jurassic batholith or Cordillera de Huacamoyos (CH; Fig. 4). Mid grey thick line: trend for Apatite Fission-Track ages; dark grey thick line: trend for Zircon Fission-Track ages. EC, SATB, DSAF, SF, CF, SAF: Eastern Cordillera, Sub-Andean Thrust Belt, Distal Sub-Andean Zone, Subandean Fault, Cosanga Fault, Sub-Andean Front. Our dataset demonstrate that: - The Subandean Fault (SF) is no longer active because the fission-track ages are identical across it since at least since 55-45 Ma because identical cooling ages across the SF indicates coeval exhumation from temperatures around 270°C (ZFT; Fig. 1) towards the surface. Hence, the Sub-Andean Thrust Belt (SATB) is part of the EC since at least the Early Eocene. - The Cosanga Fault does accommodate differential movement as suggested by the major contrast in cooling ages across it. Cooling ages are “young” in the hanging whereas they are much older in the footwall. It is thus the active fault system that localizes deformation of the Eastern Cordillera onto the Sub-Andean Zone since the Early Eocene. - Differential movements along the CF can be quantified using a geothermal gradient of 22°C/km. The AFT ages range between 6 and 2 Ma (so 4 Ma) for the hanging wall with a temperature of closure of 110°C and a surface temperature of 20°C. The hanging wall of the Cosanga Fault is thus exhuming a rate of ((110-20°C)/4Ma)/(22°C/km)=1.0 km/my. In the footwall, AFT ages are much older and the thermal model of figure 5 is used to estimate recent exhumation. Thermal model shows that cooling started roughly 30 Ma from a temperature of 70°C ((70-20°C)/30)/(25C°/km)=0.075 km/my that is more than 10 time lower than for the hanging wall.


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Conclusion: Sampling on both sides of a fault and applying low-temperature thermochronometers allow to date and quantify faulting.

2.1.3. Fault gouge/sealing dating. Ex. High-Atlas Morocco Fault gouges can be dated using précised methodology and analyses. Once the sample selected, a thin section is made that is analysed by X-ray to determine its composition and percentage in phyllosilicates. Later, a cartography of the thin section is made with a microprobe to determine which minerals are in equilibrium. Equilibrium between micas and Illite indicate the pressure for a given temperature that is indicated by chlorite. The estimated temperature for our sample is 250-225°C. There are always two families of illite in fault gouges, one in the range or smaller than two microns and a second one in the range or greater than 14 microns in length. The authigenic illite is the smallest, and was generated when the two blocks slipped. Ar/Ar thermochronological analyses on this illite are finally being produced to determine the age of the fault gouge.

Figure 7: Left: panorama of a giant recent landslide along a Triassic normal fault plane with massive tilted colluviums. The white line is the fault gouge constituted of phyllosilicates and barite that can be followed for many kilometres. Right: details of the fault plane and gouge. The footwall is a Precambrian gneiss whereas the hanging is constituted of Cambrian carbonates and Triassic siltstones. The gouge has an average width of 2 metres. The example illustrated in figure 7 is a huge Triassic Fault plate with a two meters thick gouge in the High-Atlas of Morocco. It is 1.2 km long here but can be followed many kilometres to the north and south using the white line constituted of Barite. The road is at the level of the river so we could not see the fault plane from the bottom except the tilted colluviums. We followed the procedure and analyses indicated above. Results indicate that the age of the fault gouge is still Triassic being not affected by the second and very recent slip.


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2.1.4. Changes in denudation/exhumation rates compared to sedimentation rates Ex. SE Peru Amazon basin

The southeastern Peruvian Andes include the Eastern Cordillera and Sub-Andean Zone (Fig. 8) that act today as a topographic front for the Amazon precipitation. However knowledge of changes in denudation is required to differentiate between tectonic and climatic stimulus that shapes the 1) morphology of this flank of the Andes and 2) infilling of the Andean Amazon Basin.

Figure 8: Left: DEM from South America (Cornell University) with Nazca–South American plate convergence showing the extent of the studied area. Right: geological map of the studied area with sample locations (source: 1:100 000 sheets maps INGEMMET). AAB, FT, ITS, AF, Maz., MP: Andean Amazon Basin, Frontal Thrust, Inambari Thrust System, Andean Front, town of Mazuko and Macusani Plateau. Black and white dashed line: cross-section illustrated in figure 9. I present the first zircon U-Th/He (ZHe) and AFT ages from a transect against the strike of the Andes (Figs. 7 & 8).

Figure 9. Schematic non-balanced geological cross section (see figure 8 for locality) and thermochronological ages projected onto it. The duplexes to the west of the section (SATB) are only interpretation. AFTA, ZHe, QB, AF, SATB, ITS, DSAZ, FT, AAB, PS: Apatite fission track age, zircon U-Th/He, Quincemil Basin, Andean Front, Sub-Andean Thrust Belt, Inambari Thrust System, Distal Sub-Andean Zone, Frontal Thrust, Andean Amazon Basin, Punquiri Syncline. A major increase in denudation is evidenced from the Eastern Cordillera in southern Peru at 4-3 Ma (Fig. 10) that can be correlated with a synchronous increase in the sedimentary accumulation rates from the Amazon Basin from outcrops and well data but also as far as the Amazon fan. On the basis of these results, I argue for the first order importance of a Pliocene climatic change towards more erosive conditions along the eastern slope of the Andes.


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Figure 10. Right and Bottom: AFT and Zircon U-Th/He age-elevation plot from the Eastern Cordillera of SE Peru. Left and Top: calculated sediment accumulation rates in the proximal AAB. Stratigraphic correlations in the Eastern Cordillera and Andean Amazon Basin with sedimentary thicknesses.. (1) (2) & (3): Radiometric ages from intercalated tuff layer..


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2.1.5. Inversion of the Western High-Atlas, thrust propagation (Sub-Atlas Zone)

I completed a robust U-Th/He dataset on paired apatite and zircon minerals to examine phases of uplift. The U-Th/He dataset of zircon suggests that denudation was of the order of 0.03 km/my from 90 to 30 Ma whereas the apatite dataset clearly indicates that Alpine tectonic inversion occurred since the Oligocene at an exhumation rate of 0.3 km/my (Fig. 10) generating the present-day topography of the High-Atlas mountains.

Figure 11: A) Geological map of the southern flank of the Atlas system with sample location, and U-Th/He thermochronological ages on apatite and zircon minerals (AHe, ZHe and maximum peak temperatures. Map and stratigraphic column modified from Stets (pers. com) with Palaeozoic substratum series. Cooling rates were transformed into denudation rates using the estimated geothermal gradient. TNTF, SSAZ, Alt.: Tizi N'Test fault zone, Southern Sub-Atlas Zone, Altitude. B) Age-altitude relationship for samples from the Axial Zone. Thermochronometers with the lowest temperatures of closure, i.e. fission-track and (U-Th-Sm)/He analyses on apatite are better to trace recent changes, i.e. exhumation, fault and fold development. We dated to 4.5 and 0.5 Ma (Fig. 10) the core of the frontal anticlines in the Southern-Sub-Atlas Zone (SSAZ) using U-Th-Sm/He thermochronometry (80-55°C) on


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apatite. Hence the SSAZ undergoes in sequence thrust propagation since the Late Miocene-till today. It is locus of present-day deformation in the whole Atlas system. Conclusion: Age-altitude profiles allow recognition of changes in denudation and exhumation on the hinterland and question the stimulus of these changes. In the Atlas of SW Morocco it is evident that the acceleration of denudation in the Oligocene was tectonically controlled (see below) whereas the one in the Eastern Cordillera of SE Peru has to be related to climate change because we had sediment accumulation data in the Amazon Basin.

2.1.6. Determination of Peak Temperature and its age, shale gas

Figure 12: Schematic sketch of natural gas resources (modified from Wikipedia). A: gas associated to oil reservoirs; B: conventional gas; C: coal gas; D: gas encountered in ultra-compacted reservoir; E: shale gas A new geothermometre was recently developed in 2002 and upgraded in 2010. The principle is simple and briefly detailed in section 3. Carbonaceous material is getting organized with temperature increasing. This process is irreversible and permits to determine the maximum temperature reached by any rock that hosting carbonate material. This geothermometre encompassed temperatures between 600°C and as low as the oil and gas window, i.e. 150°C. We immediately jumped onto this method when we realized its potential 1) once combined with low-temperature thermochronology and but also 2) for shale gas prospect. Shale gas is usually encountered at depths of 3000-4000 km (Fig. 11), which fit perfectly temperatures investigated by the Apatite Fission-Track (AFT; 120-60°C; Fig. 1) and U-Th-Sm/He analyses on zircon (200-160°C; Fig. 1 & 3) low-temperature thermochronometers depending on the geothermal gradient. Once its maturity temperature determined, it is possible using the accurate low-temperature thermochronometer to determine when it occurred and if this level kept or not its kerosene’s potential.


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We produced an important dataset for graphitization or peak/maximum temperature along a transect against the strike of the Atlas of Morocco (Fig. 13). The very low-grade meta-Palaeozoic (170-200°C) sediments belong to the Southern-Sub-Atlas Zone (Fig. 11). They are organic rich with a clear smell of bitumen. Still these temperatures are too high for gas prospect in southern Morocco and indicate that the potential Palaeozoic has been “overcooked”. Maximum temperatures were in the range of U-Th-Sm/He analyses on zircon. Results indicate that they were reached 260-240 Ma that was coeval with the development of a (aborted) rift system in the region.

Figure 13: Top-left: morphotectonic map of the SW Atlas system. Thick black dashed line. Topographic section illustrated in grey lines elsewhere. Numbers 1 to 6 correspond to the different morpho-tectonic domains that are in the other 3 rectangles labelled as HP, NSAZ, AZSSAZ, SP, AA: Haouz Plain, Northern Sub-Atlasic Zone, Axial Zone, Southern Sub-Atlasic Zone, Souss Plain, Anti-Atlas. HA, AA: High-Atlas, Anti-Atlas. Red lines: sections along which I sampled. Top right: U-Th-Sm/He analyses on apatite. Left-axis: Altitude. X-axis: distance. Right-axis: age in Ma. Bottom right: U-Th-Sm/He analyses on zircon. Axes are the same. Bottom Left: Peak temperature in °C (left-axis). Right axis: altitude. X-axis distance. Thermal modelling Shale by definition has a very fine granulometry. Hence Apatite and Zircon will not be met. However, it is possible to select from a well/core the 2 levels and above rich in these minerals. With the measured geothermal gradient we will correct the difference in term of position in stratigraphic column and model thermally the level that has high potential for shale gas. Conclusion: We did not know that a major oil company drilled 3 kilometres deep in the Palaeozoic - 700 kms to the east of our zone of study. They did not find any gas, or of very poor quality. To the contrary we were not surprised by this result but rather because we could have predicted it and prevented drilling.


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2.2. Detrital or indirect thermochronology. Direct approaches on bedrocks from the hinterland are sometimes limited since erosion has often removed the record of earlier stages of orogenic growth. To overcome this, we decided to study orogenic sedimentary records through the use of detrital thermochronology and heavy mineral analysis (Ruiz et al. 2004). Any detrital study is based on the notion of the lagtime (Fig. 15) and applicable to any low-temperature thermochronometer. The lagtime is detailed and explained in the figure 12. It brought a significant advance in thermochronology for the geoscientific community in terms of methodology but also geodynamics notably of the Ecuadorian Andes. The associated publication was awarded by the journal Basin Research as one of the best three of the year. Please note that transportation is almost always considered as negligible but this is untrue for example when the hinterland progressively cannibalizes the proximal series of a foreland basin. These series are not reset because they were not buried to temperatures high enough to homogenize the different age population. These series contain multiple detrital populations that are later put in the drainage basin. As a result, transport as defined in figure 16 is far from being always negligible. The detrital approach is not much applied because it requires more analyses and carefulness. This did not prevent us to update this approach and to push forward applying this approach to the recent, i.e. present-day-river. Sands are selected at the end of a drainage basin and compare results with an age-altitude profile completed from the same catchment (see 3.1.3). Our goals are multiple: 1) first we wanted to test if denudation records are identical and 2) if valid to extrapolate analyses to modern sands in order to minimize the amount of analyses. The AFT cooling ages from modern river sands but also from the vertical profile from the Eastern Cordillera in SE Peru reveal a coincidence between rapid erosion that is focused along the topographic barrier and climatic change from warm to ice-house for the Pliocene. This dataset corroborates that tectonism through important rock uplift exerted first the dominant control on the denudation pattern that was later overtaken by climate-driven erosion denudation since the Late Miocene-Pliocene.

Figure 15: The notion of lagtime in (a) a schematic cross- section and (b) within time temperature scales. The lagtime includes the time taken for the mineral to cool through the specific closure temperature, Tc, to the surface where the temperature is Ts and transported into the basin. The times of closure, exposure on the surface and time of deposition (stratigraphic age) are tc, te and td, respectively. tc1 and tc2 represent two levels in the hinterland carried into the basin with stratigraphic ages are td1 and td2.

Sediment hosting apatite, or zircon crystals keeps its provenance signature if it was not reset or partially reset, in another words heated to metastable or unstable temperature range (Fig. 1). If the sediment is reset, provenance information is deleted. As a result, it hosts the exhumation pattern of its present-day location similarly to thermal modelling of the substratum series of the basin (see 3.1.1).


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The reverse, i.e. an unreset dataset traces exhumation in the hinterland as discussed above. I do prefer to use the term substratum because it has no implication on the nature of the substratum. Sediments in a basin are most likely reset for the AHe system than for the ZFT’s one due to the important difference in temperature between the 2 unstable zones (Fig. 1). Two-three and ten kilometres of overlying sedimentary pile are required to reset these two thermochronometers respectively. These two values are considerably different; hence, using one thermochronometer rather than the other one depends on what you are looking for. Conclusion: Applications of detrital thermochronology for oil industry are many: we can tell from surface or well data if a level reached or not a certain temperature. Second, if the sample was not reset and kept its detrital signature and hence past denudation in the hinterland using the different detrital age populations. If the sediment was reset the multiple age populations are homogenized and put back to zero when thermal models, path, history of the basin could be produced as if this level was part of the substratum.

3. Methodologies

3.1. Low-temperature thermochronology

- Definitions Temperature increases with depth in the Earth and, at high temperatures, noble gases emitted in radioactive decay diffuse away. Defects (tracks) in crystals, produced by the charged particles expelled in nuclear fission, anneal. By measuring the concentrations of such gases or tracks, one can date when the sample cooled below a temperature at which diffusion or annealing becomes very slow. The cooling ages/paths provide an estimate of the average exhumation rate if combined with a geothermal gradient, which in these cases equals the rate at which material above the sampled rock has been eroded, and this is the reverse for heating/burial. Such estimates apply to periods as short as 500,000 years to as long as several 100 million years. But in all cases they span several glacial and interglacial cycles, smoothing out the effects of large climatic changes (Molnar 2003). There are four commonly used low-temperature thermochronometers. Temperatures of closure or Partial Annealing Zone or metastable temperature range are different for each thermochronometres (Fig 3). They range from 270 to 55°C. Analyses on titanite are also possible but not very common. They are usually completed when zircon is absent. The presence and extraction of apatite and zircon crystals is lithology dependant. Apatite and zircon rich lithologies are magmatic rocks, conglomerates, sandstones, siltstones and sometimes present-day river sands.

Once apatite and zircon are extracted (Fig. 4), mounts in epoxy and Teflon are made. They are polished, etched and have a low uranium sheet of mica attached to the surface. They are then sent for irradiation to determine their concentration in 235U and 238U. Counting of tracks then determines the apparent age of the samples. Analyses for U-Th-Sm/He are easier because they necessitate fewer crystals, i.e. three to five, crystals that should be inclusion free. They are packed in platinum foils and are first degassed to obtain the He concentration using a laser and a quadrupole mass spectrometer. The crystals are subsequently dissolved to obtain U, Th, Sm concentrations using Laser ablation ICPMS methodology.


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- The different thermochronometers

Figure 3: four of six low-temperature themochro-nometre, i .e. AHe, AFT, ZHe, and ZFT. Unstable indicates that within this temperature range fission, or degasing (He) occurs. Metastable correspond to the partial annealing zone discussed below.

Figure 4: Apatite and zircon crystals in reflective light.

- Resetting: A sample will be reset when it rests sufficient time in the metastable and/or unstable temperature range (Fig. 3). All its previous low-temperature information is deleted and the clock put back to 0 Ma. For a sediment, a total resetting homogenizes the different age population into a single initial 0 Ma age.

- Thermal modelling: Inverse low-temperature thermochronometric modelling is the end result of high quality datasets. Results from modelling are time-temperature envelopes that yield the long-term history of the rock being studied. Thermal models are constrained within the partial annealing zones of both 1) Fission track and 2) (U-Th)/He on apatite, i.e. 120-55°C (Fig. 2 & 3).

Thermal models quantify rates of cooling and heating from rock either exposed today at the surface or from a well (higher present-day temperature). Using a calculated geothermal gradient, it is possible to change 1) cooling and 2) heating paths/phases into 1) denudation/exhumation and 2) sedimentary/tectonic burial. In addition, thermal models image the residence time of the modelled sample within the 120-55°C isotherms (Fig. 3). Thermal models require external constraints, which are illustrated in figure 3 as an unconformity (geological constraint) and a presence at a certain temperature and time thanks to thermochronometres with higher temperature of closure.


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(For Additional information please read Reiners, P.W., Ehlers, T.A and Zeitler, P.K. Reviews in Mineralogy & Geochemistry Vol. 58, pp. 1-18, 2005). 3.2. Details on the Peak Temperature – thermal maturity method Introduction The transformation (carbonization or coalification) of carbonaceous material (CM) has been used as a proxy for studying the low-temperature evolution of rocks for quite some time, applying methods like vitrinite reflectance or Rock-Eval pyrolysis. Although some of these methods are quite reliable for studying thermal maturity in advanced diagenesis, equivalent tracers for low-grade metamorphism are still lacking. In this temperature range (from about 200 to 320°C), CM is a complex material in terms of chemistry and structure Raman spectroscopy of CM (RSCM thermometry) is used as a quantitative geothermometer for sediments in the range 330–650°C and indicates the peak temperature of a metamorphic cycle. In this temperature range, graphitization results in the irreversible polymerization and reorganization of the aromatic skeleton, for which Raman microspectroscopy provides sensitive quantitative information. The Raman spectrum of such CM is rather different from that of graphitic CM because of several additional 'defect' bands, and there is no consensus on their attribution.

Figure 13: Representative Raman spectra of carbonaceous material along 4 locations in the Alps for calibration.

Conclusion The qualitative changes in the spectra’s (Figure 13), as well as the quantitative ratios, exhibit a significant and remarkably consistent evolution with metamorphic grade, which may be used as a quantitative proxy f or metamorphic grade. Temperature is most likely the key factor controlling the structure of low- grade metamorphic CM. However, further work in various geological contexts is needed (and is in progress) to assess whether the spectral evolution observed i n t h e v e r y l o w - g r a d e r o c k s ( < 1 5 0 ° C ) may be generalized and to test whether it is possible to calibrate a general, empirical and quantitative thermometer based on the Raman spectrum of CM in lower-grade rocks. Sampling: 0.5 kgs of bedrock or from well-core, illite separation, Ar/Ar dating, an uncovered thin section, polished to 20 microns Analyses: completed in Switzerland or France


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4. Conclusions The expertise we presented you is of high importance for oil and gas prospection because it reconstructs the past thermal history of a basin within the oil & gas windows, as in the hinterland. Using the geothermal gradient phases of cooling and heating are interpreted and quantified in terms of exhumation and burial. We decided to present you the existing and the one we develop potentials of these methods. Finally, a novel approach is introduced. It combines a new geothermometer with low-thermochronology analyses to investigate gas shale. We believe in these methods as they are individually well established in academia. We are convinced that this expertise (see the Laius in the introduction) is important for Oil & Gas industry. Furthermore, we think that such study should be completed before any phase of exploration because it can generate shortcuts, avoid unnecessary investigations – in a way it will 1) probably save money but also 2) force you to have a different look at the geological object you target.

We aimed this booklet to any geoscientist, i.e. manager, petroleum geologist, structural geologist, exploration geologist, exploration manager, consultant. As a geologist, I would feel fulfilled with all these applications because I would be able to characterize and quantify an orogen-basin system using established but also novel approaches. The investigated temperatures reach 270°C so the 10 first kilometres of the crust and encompasses the oil and gas window from which time-Temperature paths are extracted with exactitude. Turn around from sampling to report can be reduced to 6 months.


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5. Modus operandi

a) Number of samples This is impossible to say how many samples are needed but we can give you examples. Pricing varies in function of the number of analyses completed on the sample and also in function of the total amount of sample selected.

• Sub-Andean Zone of Ecuador and Amazon Basin: 170 samples • Eastern Cordillera Peru and Amazon Basin: 120 samples • Western Atlas system (including basins and Sahara; 150 • Zagros Iran: 120 • Caucasus (2 section against it, Georgia and Russia) 120 • Tunisia (very small project): 40

b) Mineral separation for low-temperature thermochronology

- Selection of key lithologies from key-regions under our supervision (the amount of samples depends on the objectives) - Accurate lithologies are all magmatic rocks (volcanics, plutons, breccias), metamorphics ones if grain size is not too small, continental sediments (silt, slumps, conglomerates & sandstone). Please avoid carbonates, - Sample should weight 5-6 kgs and a thin section made - Sample is being crushed and the 355-50 microns fraction kept - Mineral separation using a wilfley table (table utilized in mining industry) - The Heavy fraction will go further in the heavy liquids separation (density of 3.1 and 3.3). Apatite mineral has a density of 3.10-3.15 whereas zircon exceeds 4. - Iron rich aggregates or minerals will be removed with a magnet - Apatite and zircon rich fractions will be cleaned thanks to hand picking if needed and acid for zircon.

Mineral separation using the new selfrag system (www.selfrag.com/analysis/OfApatite.pdf). Sample can be reduced to 1/10 of their volume and thus allow analysis on small samples such as well/cores.

c) Fission-Track analysis http://en.wikipedia.org/wiki/Fission_track_dating

- Apatites are mounted into epoxy, polished and chemically attacked with acid to reveal the tracks due to the spontaneous decay of U238. Mounts are later covered by a glass, or plastic, or mica Uranium free layer and send for irradiation by thermal neutrons to generate the fission of U235 (more stable) in a nuclear reactor. Once back the cover is


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chemically attacked generating tracks. Tracks are counted and an age is produced. Length and width of the U238 tracks are measured to allow thermal modelling.

- For Zircons the principle is the same except that there is no thermal modelling and the acids utilized are much more dangerous. For Fission-Track on apatite and zircon up to 20 crystals should de dated to get an age but more is better.

d) U-Th/He

From the Apatite and zircons separates, the most beautiful, i.e. inclusion free, size, crystals are selected and packed for determining the He content thanks to a mass quadrupole mass spectrometer whereas U and Th are determined using and ICPMS. Up to 5 crystals should be analysed to produce an age.

e) After collecting the data, they are first all put back into their geological context (map, section) before producing age-altitude profiles, and thermal modelling using existing software (HeFty) f) Reports, interpretation and conclusions

Geoffrey Ruiz Contracted by GeoLogin 3G: Geologin 3G CCSC · CCSC 87-6700 Rumble street, Burnaby,...

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