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Examples of fourier transform infrared (FT-IR) spectra obtained for fluid inclusions of varying composition: (A) H 2 O spectrum for sample VRW8B inclusion 18. (B) Spectrum indicating the presence of coexisting H 2 O-CO 2 and H 2 O-CO 2-CH 4 inclusions in sample PS3. (C) Variation of spectra for aqueous-and volatile-rich inclusions in sample PS3. (D) H 2 O-CO 2-CH 4 spectrum for sample FSG6 (after Drennan, 1997 and Drennan et al., 1999).
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Gold and uranium mineralization within the Archean Witwatersrand Basin exhibits a close association with carbonaceous matter. In order to understand the gold and uranium mineralization associations, it is necessary to understand something about the carbonaceous matter itself as well as the fluids involved in remobilizing both hydrocarbons and miner...
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... P-T-X (pressure- temperature-compositional) and geochemical data (and, hence, determine the metal-carrying capacity of the fluids and recon- struct the P-T evolution of the fluids), independent characteri- zation of paleofluids was obtained by subjecting selected fluid inclusion samples to Fourier transform infrared (FT-IR) spec- troscopy ( Fig. 2; Barres, 1990, 1992) and laser Raman spectrometric analysis ( Fig. 3; Dubessy et al., 1982Dubessy et al., , 1984Pasteris et al., 1988;Wopenka et al., 1990 (Drennan, 1997;Drennan et al., 1997Drennan et al., , 1999). These data were used to cal- culate mole percentages for each of the species present in the fluids (Table 3) as well as ...
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... REE patterns obtained by PIXE spot scans (Drennan, 1997) of individual vein nodules appear to be complex and do not resemble the patterns for granite-hosted nodules or seam bitumen (Fig. 12A). Of the five nodules, BIT1 is the least enriched in total REEs (Fig. 12B); it does exhibit high Sm and Gd concentrations and a negative Eu anomaly. BIT2, BIT3, and BIT4 are characterized by REE enrichment (Figs. 12C-12E), whereas BIT5 has the highest REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also ...
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... REE patterns obtained by PIXE spot scans (Drennan, 1997) of individual vein nodules appear to be complex and do not resemble the patterns for granite-hosted nodules or seam bitumen (Fig. 12A). Of the five nodules, BIT1 is the least enriched in total REEs (Fig. 12B); it does exhibit high Sm and Gd concentrations and a negative Eu anomaly. BIT2, BIT3, and BIT4 are characterized by REE enrichment (Figs. 12C-12E), whereas BIT5 has the highest REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr ...
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... 1997) of individual vein nodules appear to be complex and do not resemble the patterns for granite-hosted nodules or seam bitumen (Fig. 12A). Of the five nodules, BIT1 is the least enriched in total REEs (Fig. 12B); it does exhibit high Sm and Gd concentrations and a negative Eu anomaly. BIT2, BIT3, and BIT4 are characterized by REE enrichment (Figs. 12C-12E), whereas BIT5 has the highest REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr contents. BIT3 also has very high amounts of Tb present, whereas BIT5 has very high Sm and Gd concentra- tions. Although BIT4 has no Eu anomaly, it is ...
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... for granite-hosted nodules or seam bitumen (Fig. 12A). Of the five nodules, BIT1 is the least enriched in total REEs (Fig. 12B); it does exhibit high Sm and Gd concentrations and a negative Eu anomaly. BIT2, BIT3, and BIT4 are characterized by REE enrichment (Figs. 12C-12E), whereas BIT5 has the highest REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr contents. BIT3 also has very high amounts of Tb present, whereas BIT5 has very high Sm and Gd concentra- tions. Although BIT4 has no Eu anomaly, it is characterized by high Pr and Tb abundances (Fig. 12E). BIT2 exhibits a positive ...
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... nodules or seam bitumen (Fig. 12A). Of the five nodules, BIT1 is the least enriched in total REEs (Fig. 12B); it does exhibit high Sm and Gd concentrations and a negative Eu anomaly. BIT2, BIT3, and BIT4 are characterized by REE enrichment (Figs. 12C-12E), whereas BIT5 has the highest REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr contents. BIT3 also has very high amounts of Tb present, whereas BIT5 has very high Sm and Gd concentra- tions. Although BIT4 has no Eu anomaly, it is characterized by high Pr and Tb abundances (Fig. 12E). BIT2 exhibits a positive Eu anomaly and very high Tb ...
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... REE abun- dances of all five grains (Fig. 12F). BIT3 and BIT5 (Figs. 12D and 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr contents. BIT3 also has very high amounts of Tb present, whereas BIT5 has very high Sm and Gd concentra- tions. Although BIT4 has no Eu anomaly, it is characterized by high Pr and Tb abundances (Fig. 12E). BIT2 exhibits a positive Eu anomaly and very high Tb concentrations (Fig. 12C). These highly variable REE patterns do not approximate REE patterns of uraninite or uranothorite. It cannot, therefore, be argued that the REE patterns of vein nodules derive their signatures from any preexisting uranium-rich mineral but rather that these ...
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... 12F) also exhibit negative Eu anomalies, and both nodules have elevated Pr contents. BIT3 also has very high amounts of Tb present, whereas BIT5 has very high Sm and Gd concentra- tions. Although BIT4 has no Eu anomaly, it is characterized by high Pr and Tb abundances (Fig. 12E). BIT2 exhibits a positive Eu anomaly and very high Tb concentrations (Fig. 12C). These highly variable REE patterns do not approximate REE patterns of uraninite or uranothorite. It cannot, therefore, be argued that the REE patterns of vein nodules derive their signatures from any preexisting uranium-rich mineral but rather that these bitu- men nodules coprecipitated in quartz veins are chemically unique, having ...
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... sug- gestions that the source rock was not within the Witwatersrand Basin but in an overlying sequence such as the 2550 Ma dolomites of the Transvaal Supergroup, which contained abun- dant organic material now preserved as algal stromatolites, are not supported by the available evidence. Spangenberg and Frimmel (2001), for example, have demonstrated that carbona- Figure 12. C1 Chondrite-normalized REE (rare-earth element) patterns for: (A) Witwatersrand sediment-hosted seam bitumen, granite-hosted bitumen nodules ( Robb et al., 1990), and bitumen nodules extracted from late-stage quartz veins. ...
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Based on the new drilling data and field outcrop data of the Gaoshiti–Moxi area, the geochemical characteristics of the Sinian-Cambrian natural gas are studied and analyzed, including gas composition, isotope, light hydrocarbon, kerogen carbon isotope and reservoir bitumen biomarkers etc. The results show that: (1) The natural gases of the Sinian D...
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... However, it is necessary to determine whether carbon-rich upper horizons in palaeosols of the Kaapvaal Craton indeed represent ancient biological soil crust or formed differently. Important carbon sources to consider are migrating hydrocarbons associated with burial diagenesis or hydrothermal-metamorphic processes, such as caused by the emplacement of the Bushveld Igneous Complex and the Vredefort Impact at ~2.0 Ga ( Fig. 1a; Robb and Meyer, 1995;Buick et al., 1998;Drennan and Robb, 2006;Fuchs et al., 2016). ...
... Fuchs et al. (2016) documented evidence of hydrocarbon migration in BRF conglomerates and argued that hydrothermal and hydrocarbon fluids sourced from the Witwatersrand Supergroup were transported through fault networks and infiltrated the BRF. If migration of hydrocarbons occurred, evidence of this percolation would be recorded in the presence of pyrobitumen: (1) along veins/fractures in the BRF quartzites and palaeosol, (2) in the pore space between quartz grains in the BRF quartzites, and (3) as bituminous nodules, as is commonly observed in carbon-rich conglomerate seams of the Witwatersrand Supergroup (Spangenberg and Frimmel, 2001;Drennan and Robb, 2006) and conglomerate reefs of the BRF (Buick et al., 1998;Fuchs et al., 2016). No such features have been observed in the present study. ...
... There exist multiple instances of close spatial and temporal associations of gold with organic matter, such as in the renowned Witwatersrand basin, where the precipitation of native gold and uraninite was suggested to have occurred by reduction at the interface between a hydrothermal sulfidebearing fluid and hydrocarbon liquids or solids (Disnar and Sureau, 1990;Robb and Meyer, 1995;Drennan et al., 1999;Drennan and Robb, 2006;Fuchs et al., 2016). The close spatial association of gold and carbonaceous-bearing formations (including hydrocarbons) in the Carlin trend deposits has triggered the foundation for the carbonaceous trap model (Radtke and Scheiner, 1970). ...
Sediment-hosted gold deposits represent a significant portion of the world’s gold resources. They are characterized by the ubiquitous presence of organic carbon (Corg; or its metamorphosed product, graphite) and the systematic occurrence of invisible gold-bearing arsenian pyrite. Yet the role played by these features on ore formation and the distribution of gold remains a long-standing debate. Here, we attempt to clarify this question via an integrated structural, mineralogical, geochemical, and modeling study of the Shahuindo deposit in northern Peru, representative of an epithermal gold deposit contained in a sedimentary basin. The Shahuindo deposit is hosted within Lower Cretaceous fluvio-deltaic carbon-bearing sandstone, siltstone, and black shale of the Marañón fold-and-thrust belt, where intrusions of Miocene age are also exposed. The emplacement of the auriferous orebodies is constrained by structural (thrust faults, transverse faults) as well as lithological (intrusion contacts, permeable layers, anticlinal hinge in sandstone) features. The defined gold reserves (59 tons; t) are located in the supergene zone in the form of native gold grains. However, a primary mineralization, underneath the oxidized zone, occurs in the form of invisible gold in arsenian pyrite and arsenopyrite. Here, four subsequent pyrite generations were identified—namely, pyI, pyII, pyIII, and pyIV. PyI has mean Au concentrations of 0.3 ppm, contains arsenic that is not detectable, and is enriched in V, Co, Ni, Zn, Ag, and Pb compared to the other pyrite generations. This trace element distribution suggests a diagenetic origin in an anoxic to euxinic sedimentary basin for pyI. Pyrite II and pyIV have comparable mean Au (1.1 and 0.7 ppm, respectively) and As (2.4 and 2.9 wt %, respectively) concentrations and precipitated under conditions evolving from lower (pyrrhotite, chalcopyrite, sphalerite) to higher (enargite, digenite, chalcocite) sulfidation, respectively. The pyIII generation is the major gold event in the primary mineralization, with pyrite reaching 110 ppm Au (mean ~7 ppm) and 5.6 wt % As (mean ~1.8 wt %), while coeval arsenopyrite attains 460 ppm Au. Pyrite III is also enriched in other trace elements such as Se, Ge, Mo, In, Ga, and Bi compared to the other pyrite generations, which is indicative of a magmatic source. Bulk analyses of the surrounding unmineralized rocks show only parts per billion levels of Au and less than 25 ppm As. These data, combined with mass balance considerations, demonstrate that the sedimentary rocks could not be the sole source of gold, as they could only contribute a minor portion of arsenic and sulfur (and iron) to the deposit. Conversely, fluids exsolved from a pluton crystallizing at depth likely provided the great part of the gold endowment. Equilibrium thermodynamics simulations, using geochemical constraints established in this study, demonstrate that interaction between Au-As-S-Fe–bearing fluids and organic carbon-bearing rocks strongly enhanced the fluid ability to transport gold by maximizing its solubility as AuI hydrosulfide complexes via a combined increase of pH and aqueous sulfide concentration. This finding challenges the traditional qualitative view of organic matter acting exclusively as a reducing agent for AuI that should promote gold deposition in its native state (Au0) rather than enhance its solubility in the fluid. Our results have significant implications for the exploration of carbonaceous sedimentary environments. Such settings may provide a very effective mechanism for focusing gold transport. Subsequent scavenging of AuI from solution in a chemically bound form is promoted by the precipitation of arsenian pyrite in permeable structural and lithologic traps, bound by more impermeable units, similar to what occurs in petroleum systems. Our integrated study underlines the important potential of sedimentary Corg-bearing rocks in the formation and distribution of gold and associated metal resources.
... This was supported by Gray et al. (1998), who used reflected light microscopy techniques (similar to those applied to determining coal rank) and concluded that shales present in the Witwatersrand basin were the primary source of the hydrocarbon. On the basis of fluid inclusion studies, Drennan and Robb (2006) concluded that diagenetic maturation of primitive bacteria in autochthonous shale within the basin migrated through the sedimentary pile forming gold and uranium complexes. They recognized at least four separate events whereby hydrocarbon fluids migrated into the host rocks along structural surfaces such as unconformities. ...
... • The carbonaceous material was abiogenic (inorganic) in origin (Glasby 2006 and references therein). The latter theory no longer holds sway because carbon isotope studies of the pyrobitumen have shown that the carbon was organically derived (Hoefs and Schidlowski 1967;Nagy 1993;Drennan and Robb 2006). ...
... Because it seems plausible that these hydrocarbons played a fundamental role in the endowment of gold in the basin, and they are a vital component in the two recently published models, a vigorous debate has arisen about the origin of the hydrocarbons. The opinions of the investigators are generally divided over whether they originate i) from formerly migrating liquid oils (Drennan and Robb, 2006;England et al., 2002;Fuchs et al., 2017;Gray et al., 1998;Parnell, 1996Parnell, , 1999 or ii) from microbial mats that developed on exposed erosional paleosurfaces (Frimmel, 2018;Hallbauer, 1975;Hallbauer and van Warmelo, 1974;Mossman et al., 2008). Hydrocarbon nodules (commonly referred to as "flyspeck carbon" in the previous literature), either solitary or arranged in extensive veins, are present in many high-grade reefs and generally regarded to be a product of diagenetic migration of oil and their conversion to solidified pyrobitumen. ...
... Fluid inclusions preserved in quartz have been studied in several auriferous reefs, including the Basal, Vaal, Venterdorp Contact and C reefs, in order to characterize the mineralizing fluids (e.g., Coetzee et al., 1995;Drennan et al., 1999;Drennan and Robb, 2006;Frimmel et al., 1999;Stevens et al., 1997). All examples of fluid inclusions are described as being low-to moderate-salinity liquid or liquid-vapor systems that contain considerable volumes of CO 2 , carbonic gases (e.g., CH 4 ), N 2 , H 2 S, with Ca 2+ and Fe 2+ as the dominant cations. ...
... Inclusions of insoluble oil and their solid residues are common (Dutkiewicz et al., 1998;England et al., 2002;Fuchs et al., 2016a). Inclusions with a high proportion of gaseous higher hydrocarbons such as C 2 H 6 and C 3 H 8 have been documented in late-stage quartz veins that crosscut earlier populations (Drennan and Robb, 2006). ...
There is a close spatial relation between high-grade gold mineralization in the Witwatersrand basin and carbonaceous nodules, veins and seams. Hydrocarbons thus may well have been essential in ore genesis. We have sampled four major gold-, uranium- and hydrocarbon-bearing ore horizons, namely the Carbon Leader, Vaal, B and Black reefs, to determine the role of hydrocarbons in the accumulation and hydrothermal fixation of gold. Our multipronged approach included high-resolution scanning and transmission electron microscopy (SEM, TEM), nanotomography with video clips, and geochemical modeling. Post-depositional hydrothermal activity at the peak of regional metamorphism produced an assemblage of quartz, phyllosilicates, brannerite, crandallite, florencite, monazite and gold in all four reefs. The gold, hydrocarbons and associated mineral assemblages are closely related on the micro to nano scale. Gold deposition occurred in interstices, as fracture fillings in detrital minerals, and on the surface of migrated solid hydrocarbon residues. The spherical to elliptical inclusions in the gold consist of an outer pyrobitumen phase and a central void space, partially associated with nanometric gold, uraninite, coffinite and silica. The hydrocarbon-bearing inclusion likely formed by the entrapment of a fossil liquid oil precursor during gold precipitation. The oil was subsequently thermally altered and converted into the final pyrobitumen and gaseous residues. Geochemical calculations to simulate the interaction of an invading hot hydrothermal fluid with the hydrocarbons in the reefs reveal that a very small amount of hydrocarbons will drastically decrease the aqueous solubility of gold and hence cause its instant precipitation.
We extend our genetic model for the epigenetic formation of gold in the Witwatersrand. Regional metamorphism promoted the extensive and likely basin-wide circulation of hydrothermal fluids; these were capable of mobilizing substantial amounts of gold. The liquid, gaseous and solid hydrocarbons in the reefs acted as efficient chemical traps for the concentration of gold. Being strong chemical reductants, they caused the rapid precipitation and accumulation of gold on the surface of the fossil oil droplets and already solidified hydrocarbons. The release of the gases from accessible hydrocarbons into the sediments away from their source buffered the redox state of the hydrothermal solutions even at a considerable distance from the pyrobitumen seams and veins, likely resulting in the deposition of gold in the absence of visible hydrocarbons. Although our findings do not explain the ultimate origin and exceptional endowment of gold in the Witwatersrand, we do provide intriguing evidence for the large-scale hydrothermal mobilization, accumulation and fixation of gold mediated by hydrocarbons during post-depositional metamorphism.
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a fluvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a fluvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
Within the eastern portion of the Carletonville gold field, the gold- and uranium-rich Carbon Leader reef of the Central Rand Group (Witwatersrand Supergroup) is truncated by an erosion channel. This channel is asymmetrical and lenticular in shape, measuring 150 to 180 m in width and up to 100 m in depth. High-resolution seismic data show that the erosion channel cuts from the Carbon Leader reef into all older units of the Central Rand Group down to the Roodepoort Formation of the underlying West Rand Group. A total of seven bore-holes were drilled into the channel, revealing that it is composed of quartzite at its base (9 m thick), overlain by deformed (lower) and laminated (upper) chloritoid-bearing shale (21 m thick) and quartzite (18 m thick). The Carbon Leader reef is highly enriched in gold (5–40 g/t Au), whereas the gold tenor of the erosion channel fill is in general much lower (<1 g/t Au), although locally grades of as much as 3.8 g/t Au are reached. Detailed seismic, sedimentological, and petrographic analyses revealed that the channel was filled with locally sourced sediments from the Main Formation. A closed-system mass balance further demonstrates that gold in the erosion channel could have been entirely sourced from the Carbon Leader reef. Sediment load played a crucial role in the distribution of gold in the channel, thus supporting a stratigraphically controlled modified placer model for the origin of gold in the Carbon Leader reef.
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a uvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a uvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a uvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
... The Carbon Leader reef is composed of conglomerates with wellrounded quartz and chert particles (0.2-24.0 mm; Fig. 7A, B) consistent with a uvial origin. From the two types of carbonaceous matter described earlier, pyrobitumen globules have been interpreted by Gray et al. (1998), Drennan andRobb, (2006), andFuchs et al. (2016) to represent migrating oils. Pyrobitumen globules were observed in both lower and upper quartzite, as well as in the chloritoid-rich shale within the erosion channel. ...
Within the eastern portion of the Carletonville gold field, the gold- and uranium-rich Carbon Leader reef of the Central Rand Group (Witwatersrand Supergroup) is truncated by an erosion channel. This channel is asym- metrical and lenticular in shape, measuring 150 to 180 m in width and up to 100 m in depth. High-resolution seismic data show that the erosion channel cuts from the Carbon Leader reef into all older units of the Central Rand Group down to the Roodepoort Formation of the underlying West Rand Group. A total of seven bore- holes were drilled into the channel, revealing that it is composed of quartzite at its base (9 m thick), overlain by deformed (lower) and laminated (upper) chloritoid-bearing shale (21 m thick) and quartzite (18 m thick). The Carbon Leader reef is highly enriched in gold (5–40 g/t Au), whereas the gold tenor of the erosion channel fill is in general much lower (<1 g/t Au), although locally grades of as much as 3.8 g/t Au are reached. Detailed seismic, sedimentological, and petrographic analyses revealed that the channel was filled with locally sourced sediments from the Main Formation. A closed-system mass balance further demonstrates that gold in the ero- sion channel could have been entirely sourced from the Carbon Leader reef. Sediment load played a crucial role in the distribution of gold in the channel, thus supporting a stratigraphically controlled modified placer model for the origin of gold in the Carbon Leader reef.
... A close relationship between hydrocarbons and gold deposits has been established in the previous studies (Radtke and Scheiner 1970;Sverjensky 1984;Radtke 1985;Ilchik et al. 1986;Gorzhevskiy 1987;Parnell 1988;Nelson 1990;Berger and Bagby 1991;Pearcy and Burruss 1993;Gize and Manning 1993;Hulen 1993;Nicholson 1994;Kuehn and Rose 1995;Arehart 1996;Robb et al. 1997;Hulen et al. 1998;Zhuang et al. 1999;Hulen and Collister 1999;Emsbo et al. 1999;Mossman 1999;Parnell and McCready 2000;Sherlock 2000;Mastalerz et al. 2000;Drennan and Robb 2006;Bao and Guha 2007;Mossman et al. 2008;Schaefer et al. 2010;Bao 2001;Large et al. 2011;Gu et al. 2002Gu et al. , 2012Gaboury 2013;Stein 2014;Wenzhi et al. 2015;Molnár et al. 2016;Migdisov et al. 2017;Frimmel 2018;Crede et al. 2019;Ozdemir and Palabiyik 2019a, b). It has been reported and illustrated that gold deposits and hydrocarbon reservoirs in the same sedimentary basin are formed as a result of joint transport and accumulation of gold and hydrocarbons occurred in the same sedimentary basin by the same fluid (Zhuang et al. 1999;Gu et al. 2012;Ozdemir and Palabiyik 2019a, b). ...
In recent studies, the links between hydrocarbon accumulations and gold mineralizations have been examined. According to the results obtained from these studies, it has been reported that gold and hydrocarbons are carried and deposited by the same hydrothermal fluids. In the Seferihisar Uplift, the Efemçukuru Gold Operation possesses the largest proven gold reserves of Turkey. For this reason, in this study, it is aimed to investigate the oil and gas potential of the Seferihisar Uplift by conducting total petroleum hydrocarbons analyses on the samples taken from the natural cold water resources. As a result of the analyses conducted, hydrocarbons have been detected in all the water samples. Organic geochemical methods have been used to determine the source of hydrocarbons detected in the water resources. The n-alkane hydrocarbons found in the water samples are the mature petroleum hydrocarbons, which are the geochemical evidence for a working petroleum system in the study area. Due to the presence of mature hydrocarbon-rich waters, the main structure in a maximum of 765 m depth determined in the study area
according to gravity and magnetic data has a significant hydrocarbon potential to become an oil and/or gas reservoir.
Keywords: reservoir-targeted oil and gas exploration, total petroleum hydrocarbons (TPH) in water analysis, hydrocarbon-rich water, Bornova Flysch Zone, gold deposit
... Cata-, meso and epi-impsonite have only been observed in quartz lodes associated with a rather monotonous U mineralization in comparison with the carbon-bearing mineral assemblages dealt with in Sections 5.2 and 5.3 (Dill, 1983a,b) (Fig. 3d). Secondary products of petroleum generating system such as solid hydrocarbon residues are characteristically highly pleochroic adjacent to grains of U minerals such as uraninite or coffinite, a phenomenon absent in the uraniferous quartz lodes hosting impsonite (Drennan and Robb, 2006). It can only been interpreted that the bombardment with α-particles was not long enough to cause any radiation damage visible under the incident light microscope. ...
Along the western edge of the Bohemian Massif, SE Germany, graphitic carbon occurs in metabasic rocks plus calcsilicates, metabiolites, and paragneisses (graphite I), in pegmatites (graphite II) and in mineralized structure zones (semigraphite and impsonite) The current studies unveiled these graphitic carbon compounds are strikingly different with regard to their age and temperature of formation: Graphite I ( 324 Ma, 570 to 625 °C), graphite II (3173 Ma, > 400°C), semi-graphite (305 Ma, 225 to 400°C), impsonite (< 298 4 Ma, 100 to 363 °C). Semi-graphite takes a special position among these graphitic carbon compounds because it links the different carbon modifications with regard to its age of formation, its structural position and its S- and C isotopes that point to a mantle and crustal influence on its formation in contrast to graphite (graphite I : crustal, graphite II : mantle) and impsonite (mantle). Semi-graphite precipitated in a fault zone which evolved from a zone of strong felsic mobilization in metabasic rocks spawning K-Na feldspar-quartz pegmatoids/aploids. During conversion of a pre-existing zone of felsic mobilization into a brittle shearzone not only carbonaceous matter but also Ni-, Pb-, Cu-, Zn-, As-, Fe-, Hg- and Mo sulfides were concentrated. The semi-graphite-bearing mineralized zone is located near rare element pegmatites hosting graphite flakes. The C-bearing systems are useful pathfinders to locate structurebound mineral deposits hosting U or base metals in the Variscan orogen.
The structurebound metalliferous semi-graphite mineralization in metabasic rocks can be taken as a reference type of dual-source hydrocarbon immigration into fault zones, syn- to postkinematically relative to the fault movement. The model can be applied to host rocks undergoing retrograde medium- to very-low-grade stage dynamo-metamorphic conditions.
To elucidate the complex history of the various types of graphite and metamorphosed bitumen a multidisciplinary approach has been taken involving petrographic and geological field mapping combined with drill core examination, petrographic and ore microscopy supplemented by electron microprobe, X-ray diffraction and scanning electron microscopy with EDX, micro-Raman spectroscopy in addition to classical coal petrographic studies, and inorganic geochemistry of major and minor elements and isotope (carbon and sulfur) chemical analysis followed up by a statistical treatment of the various chemical datasets.
... . However, uranium also causes radioactive alterations of uraniferous OM with a higher reflectance and structural changes (e.g., localised cleavage of OM-OH bonds and damage to OM-functional groups; Cumberland et al., 2016;Sýkorová et al., 2016;Smieja-Król et al., 2009;Drennan and Robb, 2006;Schlepp et al., 2001;Landais, 1996;Nagy et al., 1993;Leventhal et al., 1986;Sassen, 1984;Gentry et al., 1976). Xu et al. (2015) found that coffiniteproduced radiation resulted in the carbonization of the surrounding OM and the lattice defects of the coffinite itself within black shale-hosted polymetallic sulfide ore layer. ...
... Havelcová et al. (2014) observed that there was a decrease in H/C, O/C ratio with the increased uranium concentrations within coals in the Sokolov Basin. It has been widely reported that the structure of OM partly breaks down, and organic matter maturation increases for uranium-bearing coal, carbonaceous debris (CD), and bitumen by the methods of optical microscopy, electron microscopy, organic elemental analysis, pyrolysis GC-MS, and micro-spectroscopic techniques (Cumberland et al., 2016;Sýkorová et al., 2016;Havelcová et al., 2014;Smieja-Król et al., 2009;Drennan and Robb, 2006;Landais et al., 1990;Leventhal et al., 1986;Liu et al., 1980;Gentry et al., 1976). However, CD is rarely studied by the methods of coal property analyses. ...
Carbonaceous debris (CD) is widely distributed in the sandstone of the Daying Uranium Deposit, northern Ordos Basin, and coexists with uranium minerals, which provides a favorable case for studying their relationship. Vitrinite reflectance (VR), macerals, moisture, volatile matter, ash, total sulfur (St) and uranium concentration of CD within the sandstone were studied. The results show that VR ranges from 0.372 %Ro to 0.510 %Ro with an average value of 0.438 %Ro, indicating that CD is in the stage of lignite. The contents of vitrinite (V), inertinite (I) and minerals range from 83.18%–99.48%, 0–7.70%, and 0.34%–15.72%, respectively, with the corresponding average value of 95.51%, 1.34%, and 3.15%, respectively which indicates that V is the major maceral. Moisture on air dried basis (Mad), volatile matter yield on dry, ash-free basis (Vdaf), ash yield on dried basis (Ad) and St mostly range from 7.95%–16.09%, 44.70%–66.54%, 4.84%–26.24% and 0.24%–1.12%, respectively, while their average values are 12.43%, 53.41%, 16.57% and 0.77%, respectively. It suggests that CD is of medium-high moisture, super-high volatile matter, low-medium ash and low sulfur. Uranium concentration ranges from 29 ppm to 92 ppm with an average value of 50 ppm, and uranium concentration increases with the decreased distance to CD. On the whole, Mad and Vdaf decrease with increasing burial depth, which indicates that CD experienced the burial metamorphism. However, Mad and Vdaf obviously decrease in uranium-rich areas whereas Ad and St noticeably increase. Comprehensive studies suggest that there is a certain relationship between uranium enrichment and CD. CD in the stage of lignite helps the adsorption of uranium. On one hand, radioactivity uranium enrichment makes organic matter maturation increase with a decrease in moisture and volatile matter. On the other hand, an increase in organic matter maturation, caused by radioactivity uranium enrichment, results in an increase in uranium minerals, which is instructive in the study of regional uranium mineralization and metallogenic regularity.
