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Sample records for catagenesis

  1. Living microbial ecosystems within the active zone of catagenesis: Implications for feeding the deep biosphere

    Science.gov (United States)

    Horsfield, B.; Schenk, H. J.; Zink, K.; Ondrak, R.; Dieckmann, V.; Kallmeyer, J.; Mangelsdorf, K.; di Primio, R.; Wilkes, H.; Parkes, R. J.; Fry, J.; Cragg, B.

    2006-06-01

    Earth's largest reactive carbon pool, marine sedimentary organic matter, becomes increasingly recalcitrant during burial, making it almost inaccessible as a substrate for microorganisms, and thereby limiting metabolic activity in the deep biosphere. Because elevated temperature acting over geological time leads to the massive thermal breakdown of the organic matter into volatiles, including petroleum, the question arises whether microorganisms can directly utilize these maturation products as a substrate. While migrated thermogenic fluids are known to sustain microbial consortia in shallow sediments, an in situ coupling of abiotic generation and microbial utilization has not been demonstrated. Here we show, using a combination of basin modelling, kinetic modelling, geomicrobiology and biogeochemistry, that microorganisms inhabit the active generation zone in the Nankai Trough, offshore Japan. Three sites from ODP Leg 190 have been evaluated, namely 1173, 1174 and 1177, drilled in nearly undeformed Quaternary and Tertiary sedimentary sequences seaward of the Nankai Trough itself. Paleotemperatures were reconstructed based on subsidence profiles, compaction modelling, present-day heat flow, downhole temperature measurements and organic maturity parameters. Today's heat flow distribution can be considered mainly conductive, and is extremely high in places, reaching 180 mW/m 2. The kinetic parameters describing total hydrocarbon generation, determined by laboratory pyrolysis experiments, were utilized by the model in order to predict the timing of generation in time and space. The model predicts that the onset of present day generation lies between 300 and 500 m below sea floor (5100-5300 m below mean sea level), depending on well location. In the case of Site 1174, 5-10% conversion has taken place by a present day temperature of ca. 85 °C. Predictions were largely validated by on-site hydrocarbon gas measurements. Viable organisms in the same depth range have been proven using 14C-radiolabelled substrates for methanogenesis, bacterial cell counts and intact phospholipids. Altogether, these results point to an overlap of abiotic thermal degradation reactions going on in the same part of the sedimentary column as where a deep biosphere exists. The organic matter preserved in Nankai Trough sediments is of the type that generates putative feedstocks for microbial activity, namely oxygenated compounds and hydrocarbons. Furthermore, the rates of thermal degradation calculated from the kinetic model closely resemble rates of respiration and electron donor consumption independently measured in other deep biosphere environments. We deduce that abiotically driven degradation reactions have provided substrates for microbial activity in deep sediments at this convergent continental margin.

  2. Formation of magnetic minerals at hydrocarbon-generation conditions

    OpenAIRE

    Abubakar, R.; Muxworthy, A. R.; Sephton, M.A.; Southern, P.; Watson, J. S.; Fraser, A.J.; Almeida, T.P.

    2015-01-01

    In this paper, we report the pyrolysis and formation of magnetic minerals in three source rock samples from the Wessex Basin in Dorset, southern England. The experimental conditions in the laboratory recreated the catagenesis environment of oil source rocks. Magnetic analysis of both the heated and the unheated samples at room temperature and at very low-temperatures (5 K), coupled with transmission electron-microscopy imaging and X-ray analysis, revealed the formation of nanometre-sized (...

  3. Maturation related changes in the distribution of ester bound fatty acids and alcohols in a coal series from the New Zealand Coal Band covering diagenetic to catagenetic coalification levels

    Energy Technology Data Exchange (ETDEWEB)

    Glombitza, C.; Mangelsdorf, K.; Horsfield, B. [German Research Cemter of Geoscience GFZ, Potsdam (Germany)

    2009-10-15

    Several lignites and coals of low to moderate maturation levels from the New Zealand Coal Band were investigated using alkaline ester cleavage experiments to reveal compositional changes of ester bound components during increasing maturation. Ester bound alcohols are found to be present in highest amounts in the very immature lignite samples but show a rapid decrease during early diagenesis. Ester bound fatty acids also show an initial exponential decrease during diagenesis but reveal an intermittent increase during early catagenesis before decreasing again during main catagenesis. This was related to the short chain fatty acids. To obtain a maturity related signal and to eliminate facies related scattering in the amounts of fatty acids in the coal samples, the carbon preference index of fatty acids (CPIFA) parameter is introduced. For the long chain fatty acids the CPIFA decreases with increasing maturity. During diagenesis, the same trend can be observed for the short chain fatty acids but the intermittent increase in the amounts of short chain fatty acids is also accompanied by high CPIFA values. This indicates less altered organic biomass at this maturation level and is in contrast to the mature CPIFA signal of the long chain fatty acids of the same samples. Thus could be due to extremely different amounts of short and long chain fatty acids in the original source organic matter or it could due to the incorporation of immature bacterial biomass from deep microbial communities containing C{sub 16} and C{sub 18} fatty acids as main cell membrane components. Deep microbial life might be stimulated at this interval by the increasing release of thermally generated potential substrates from the organic matrix during early catagenesis. The high amounts of alcohols in the immature lignite samples are also visible in the alkene distribution from the open system pyrolysis experiments of the organic matrix before and after saponification.

  4. Relationship between the physico-mechanical properties of middle carboniferous rock of the Donetsk Basin coal-bearing basins and the depth of stratification. [Dependence on depth and degree of metamorphism

    Energy Technology Data Exchange (ETDEWEB)

    Sverzhevskii, V.L.; Karnaukhova, L.A.; Pikalova, V.P.

    1977-06-01

    A compilation was made of data indicating the relationship between the stratal depth and physico-mechanical properties of aleurite, argyllite and sandstone in various zones and graphs of coal metamorphism. Also indicated are the relative changes in the hardness limits during compression in relation to lithological-petrographic and textural factors, depth and catagenesis, and categenesis alone. The comparative data indicate that the physico-mechanical properties of middle Carboniferous limestone are practically independent of the depth of occurrence, and are significantly dependent upon categories. 4 references, 2 tables.

  5. Lithogenic transformation of clay in zones of abnormally high stratal pressure. Litogeneticheskie preobrazovaniya glin v zonakh anomal'no vysokikh plastovykh davlenii

    Energy Technology Data Exchange (ETDEWEB)

    Zkhus, I.D.; Bakhtin, V.V.

    1979-01-01

    An examination is made of problems associated with the properties of clays as an mantles over petroleum and gas beds with abnormally high stratal pressures (AHSP), with changes in the clays that are characteristic of AHSP zones, with catagenetic transformations of clay minerals, and with their superimposed catagenesis under the influence of fluids in the interstitial coronas. The study of the lithogenetic transformations of clay was shown to be of practical use for forecasting AHSP zones and estimating stratal pressures as well as for the operative development of an optimal system for drilling deep wells. The gradient distribution of AHSP for the layer of clay mantles was demonstrated for the first time as was the coincidence of the maximum values of those gradients with the hydrodynamic threshold. The over-all effect of dispersing rock in the AHSP zones was shown to have a universal significance and importance to forecasting beds with AHSP and the safe drilling of boreholes by means of the timely identification of AHSP zones. Calculations were made for the first time on the effect that the thickness of mantles has on fracture time of the fluids. 150 references, 27 figures, 21 tables.

  6. Thermal stability of ladderane lipids as determined by hydrous pyrolysis

    Science.gov (United States)

    Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

    2008-01-01

    Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

  7. The relationship between dolomitization and organic matter occurrence in Lower Paleozoic carbonate in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on observations on the core and surface sections of Lower Paleozoic carbonate in the Ordos Basin, petrography research and measurements of TOC, TOS , Ro, XRD, and comparative study with dolomite in modern Coorong Lake, it has been revealed that: (i)dolomitization may occur in micrite limestone, gypsum-halite and argillaceous sandstone, and it can be divided into three types: sedimentary penecontemporaneous-early diagenesis, late diagenesis of deep burial and catagenesis of uplift period. However, the crystal cell of the second type less than 35 μ m in size is most closely associated with gas pool; (ii) the highest content of organic matter (OM) is produced in samples from the argillic dolomite which may be formed by argillaceous fluid through gypsum-halite; (iii) in the evolution process from penecontemporaneous dolomite into stoichiometric dolomite, the crystal order of dolomite and the porosity of its host rock tend to increase, which is favorable to the formation of an available migration network. When the power of the fluid is high enough, the network is mainly favorable to the migration and transport of heat, but when the power of the fluid goes down, the network system is favorable, due to its large space, to OM deposition in it.

  8. Characteristics of Mire Soils and Its Sustainable Utilization in Xianghai Mire Wetland.%向海沼泽湿地土壤特征及可持续利用

    Institute of Scientific and Technical Information of China (English)

    白军红; 余国营; 张玉霞

    2001-01-01

    On the basis of the study about the conditions and process of formation of mire soils in Xianghai mire wetland, this paper classifies the soil into four soil subtypes, and describes their main characters such as distribution laws, profile features etc. respectively. In addition, it also puts forward such ways of sustainable exploitation and utilization to solve such problems as salinization, desertification and catagenesis etc..%基于对向海沼津湿地土壤形成条件和主要成土过程的研究,将其沼泽土壤划分为4个亚类型,并分别描述了各自的分布规律和剖面特征。在向海沼泽湿地土壤盐渍化、沙化、退化问题日益严重的大前提下提出了可持续开发利用对策。

  9. Forecast of phase state and composition of hydrocarbon systems of subsalt formations of the north Caspian region

    International Nuclear Information System (INIS)

    Full text : Major concentrations of hydrocarbon resources of the Caspian basin are associated with deep horizons. In experimental investigations the forecast of hydrocarbon phase state at the great depths of the oil, gas condensate and gas fields of Precaspian basin has been made and the postion petroleum within the phase-genetic range of the vertical zonation of hydrocarbons from the Precaspain are has been determined from a series of geological and geochemical indices (composition petroleum, individual composition of light and heavy fractions of hydrocarbons. The extended catagenesis zonation and consequently, a low temperature gradient of west and south areas have predetermined generation of gas-condensate and gas pools. Ona can assign those systems to supercritical under saturated systems associated with the high temperature and pressure. The violation of a normal relation in a distribution of liquid and gaseous phases exhibited in those systems is owed to the occurrence of acid components in the composition of formation gas. The content of condensate and gas factor are controlled by the concentration of acid components of formation system. The The higher content of acid components (Hs, S, CO2) in formation gas the lower is the condensate content and gas factor of the oil.

  10. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1996-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  11. Transition metal catalysis in the generation of petroleum and natural gas. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mango, F.D.

    1997-01-21

    This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalytically robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process: The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.

  12. Transition metal catalysis in the generation of petroleum and natural gas. Final report, September 1, 1992--October 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Mango, F.D.

    1997-01-21

    This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalytically robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process. The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.

  13. Diamondoid hydrocarbons as a molecular proxy for thermal maturity and oil cracking: Geochemical models from hydrous pyrolysis

    Science.gov (United States)

    Wei, Z.; Moldowan, J.M.; Zhang, S.; Hill, R.; Jarvie, D.M.; Wang, Hongfang; Song, F.; Fago, F.

    2007-01-01

    A series of isothermal hydrous pyrolysis experiments was performed on immature sedimentary rocks and peats of different lithology and organic source input to explore the generation of diamondoids during the thermal maturation of sediments. Oil generation curves indicate that peak oil yields occur between 340 and 360 ??C, followed by intense oil cracking in different samples. The biomarker maturity parameters appear to be insensitive to thermal maturation as most of the isomerization ratios of molecular biomarkers in the pyrolysates have reached their equilibrium values. Diamondoids are absent from immature peat extracts, but exist in immature sedimentary rocks in various amounts. This implies that they are not products of biosynthesis and that they may be generated during diagenesis, not just catagenesis and cracking. Most importantly, the concentrations of diamondoids are observed to increase with thermal stress, suggesting that they can be used as a molecular proxy for thermal maturity of source rocks and crude oils. Their abundance is most sensitive to thermal exposure above temperatures of 360-370 ??C (R0 = 1.3-1.5%) for the studied samples, which corresponds to the onset of intense cracking of other less stable components. Below these temperatures, diamondoids increase gradually due to competing processes of generation and dilution. Calibrations were developed between their concentrations and measured vitrinite reflectance through hydrous pyrolysis maturation of different types of rocks and peats. The geochemical models obtained from these methods may provide an alterative approach for determining thermal maturity of source rocks and crude oils, particularly in mature to highly mature Paleozoic carbonates. In addition, the extent of oil cracking was quantified using the concentrations of diamondoids in hydrous pyrolysates of rocks and peats, verifying that these hydrocarbons are valuable indicators of oil cracking in nature. ?? 2006 Elsevier Ltd. All rights

  14. Carbon and hydrogen isotopic reversals in deep basin gas: Evidence for limits to the stability of hydrocarbons

    Science.gov (United States)

    Burruss, R.C.; Laughrey, C.D.

    2010-01-01

    During studies of unconventional natural gas reservoirs of Silurian and Ordovician age in the northern Appalachian basin we observed complete reversal of the normal trend of carbon isotopic composition, such that ??13C methane (C1) >??13C ethane (C2) >??13C propane (C3). In addition, we have observed isotopic reversals in the ??2H in the deepest samples. Isotopic reversals cannot be explained by current models of hydrocarbon gas generation. Previous observations of partial isotopic reversals have been explained by mixing between gases from different sources and thermal maturities. We have constructed a model which, in addition to mixing, requires Rayleigh fractionation of C2 and C3 to cause enrichment in 13C and create reversals. In the deepest samples, the normal trend of increasing enrichment of 13C and 2H in methane with increasing depth reverses and 2H becomes depleted as 13C becomes enriched. We propose that the reactions that drive Rayleigh fractionation of C2 and C3 involve redox reactions with transition metals and water at late stages of catagenesis at temperatures on the order of 250-300??C. Published ab initio calculated fractionation factors for C-C bond breaking in ethane at these temperatures are consistent with our observations. The reversed trend in ??2H in methane appears to be caused by isotopic exchange with formation water at the same temperatures. Our interpretation that Rayleigh fractionation during redox reactions is causing isotopic reversals has important implications for natural gas resources in deeply buried sedimentary basins. ?? 2010.

  15. Experiments on δ 34S mixing between organic and inorganic sulfur species during thermal maturation

    Science.gov (United States)

    Amrani, Alon; Said-Ahamed, Ward; Lewan, Michael D.; Aizenshtat, Zeev

    2006-10-01

    Reduced sulfur species were studied to constrain isotopic exchange-mixing with synthetic polysulfide cross-linked macromolecules (PCLM), model sulfur containing molecules and natural sulfur-rich kerogen, asphalt and oil of the Dead Sea area. PCLM represents protokerogens that are rich in sulfur and thermally unstable. Mixing rates of PCLM with HS-(aq) (added as (NH 4) 2S (aq)) at low to moderate temperatures (50-200 °C) are rapid. Elemental sulfur and H 2S (gas) fully mix isotopes with PCLM during pyrolysis conditions at 200 °C. During these reactions significant structural changes of the PCLM occur to form polysulfide dimers, thiolanes and thiophenes. As pyrolysis temperatures or reaction times increase, the PCLM thermal products are transformed to more aromatic sulfur compounds. Isotopic mixing rates increase with increasing pyrolysis temperature and time. Polysulfide bonds (S-S) in the PCLM are responsible for most of these structural and isotopic changes because of their low stability. Conversely, sulfur isotope mixing does not occur between dibenzothiophene (aromatic S) or hexadecanthiol (C-SH) and HS-(aq) at 200 °C after 48 h. This shows that rates of sulfur isotope mixing are strongly dependent on the functionality of the sulfur in the organic matter. The order of isotopic mixing rates for organic matter is kerogen > asphalt > oil, which is inverse to their sulfur thermal stability. Asphalt and oil with more refractory sulfur show significantly lower isotopes mixing rates than the kerogen with more labile sulfur. Based on the findings of the present study we suggest that sulfur isotopes mixing can occur from early diagenesis into catagenesis and result in isotopic homogenization of the inorganic and organic reduced sulfur pools.

  16. Formation of nanoporous pyrobitumen residues during maturation processes within the Barnett Shale (Fort Worth Basin)

    Science.gov (United States)

    Bernard, S.; Wirth, R.; Schreiber, A.; Schulz, H.-M.; Horsfield, B.

    2012-04-01

    Hydrocarbon generation processes occur within organic-rich shales as a response to increases in thermal maturation. Shale gas reservoir quality is thought to be largely dependent on the extent to which solid organic material has been converted to pore space during catagenesis. Although pores may drastically vary in variety and abundance within differing shales, the occurrence of nanopores within organic particles has recently been documented for an important number of gas shale systems (i.e., Barnett, Haynesville, Utica, Eagle Ford, Woodford, Horn River, Marcellus, Posidonia …). However, despite their ubiquitous nature, the formation and the geochemical nature of these nanoporous organic compounds remain unclear. Here, we present the characterization of samples from the organic-rich Mississippian Barnett shale gas system (Fort Worth Basin, Texas, USA) at varying stages of thermal maturation. Using a combination of compositional organic geochemistry and spectromicroscopy techniques, including synchrotron-based scanning transmission X-ray microscopy (STXM - data collected using the CLS 10ID-1 STXM beamline) and transmission electron microscopy (TEM), we document a net increase in sample geochemical heterogeneity with increasing maturity. In addition to the presence of bitumen in samples of oil window maturity, very likely genetically derived from thermally degraded kerogen, the formation of nanoporous pyrobitumen has been inferred for samples of gas window maturity, likely resulting from the formation of gaseous hydrocarbons by secondary cracking of bitumen compounds. By providing in-situ insights into the fate of bitumen and pyrobitumen as a response to the thermal evolution of the macromolecular structure of kerogen, the present contribution constitutes an important step towards better constraining hydrocarbon generation processes occurring within unconventional gas shale systems.

  17. Studying of shale organic matter structure and pore space transformations during hydrocarbon generation

    Science.gov (United States)

    Giliazetdinova, Dina; Korost, Dmitry; Gerke, Kirill

    2016-04-01

    Due to the increased interest in the study of the structure, composition, and oil and gas potential of unconventional hydrocarbon resources, investigations of the transformation of the pore space of rocks and organic matter alterations during the generation of hydrocarbon fluids are getting attention again. Due to the conventional hydrocarbon resources decreasing, there will be a necessity to develop new unconventional hydrocarbon resources. Study of the conditions and processes of hydrocarbon generation, formation and transformation of the pore space in these rocks is pivotal to understand the mechanisms of oil formation and determine the optimal and cost effective ways for their industrial exploration. In this study, we focus on organic matter structure and its interaction with the pore space of shales during hydrocarbon generation and report some new results. Collected rock samples from Domanic horizon of South-Tatar arch were heated in the pyrolyzer to temperatures closely corresponding to different catagenesis stages. X-ray microtomography method and SEM were used to monitor changes in the morphology of the pore space and organic matter structure within studied shale rocks. By routine measurements we made sure that all samples (10 in total) had similar composition of organic and mineral phases. All samples in the collection were grouped according to initial structure and amount of organics and processed separately to: 1) study the influence of organic matter content on the changing morphology of the rock under thermal effects; 2) study the effect of initial structure on the primary migration processes for samples with similar organic matter content. An additional experiment was conducted to study the dynamics of changes in the structure of the pore space and prove the validity of our approach. At each stage of heating the morphology of altered rocks was characterized by formation of new pores and channels connecting primary voids. However, it was noted that

  18. In search of early life: Carbonate veins in Archean metamorphic rocks as potential hosts of biomarkers

    Science.gov (United States)

    Peters, Carl A.; Piazolo, Sandra; Webb, Gregory E.; Dutkiewicz, Adriana; George, Simon C.

    2016-11-01

    to - 4 ‰ and δ18OVPDB ranging from - 18 ‰ to - 12 ‰. Evidently, the migration and entrapment of hydrocarbons occurred after peak metamorphism under temperatures congruous with late catagenesis and from fluids of different compositions. The relatively high temperatures of vein formation and the known geotectonic history of the rocks analysed suggest a probable minimum age of 1.8 billion yrs (Paleoproterozoic). Our results demonstrate that post peak-metamorphic veins provide an exciting opportunity in the search for evidence of early life. The integration of petrological and organic geochemical techniques is crucial for any future studies that use biomarkers to reconstruct the early biosphere.

  19. Comparison of GC-MS, GC-MRM-MS, and GC × GC to characterise higher plant biomarkers in Tertiary oils and rock extracts

    Science.gov (United States)

    Eiserbeck, Christiane; Nelson, Robert K.; Grice, Kliti; Curiale, Joseph; Reddy, Christopher M.

    2012-06-01

    Higher plant biomarkers occur in various compound classes with an array of isomers that are challenging to separate and identify. Traditional one-dimensional (1D) gas chromatographic (GC) techniques achieved impressive results in the past, but have reached limitations in many cases. Comprehensive two-dimensional gas chromatography (GC × GC) either coupled to a flame ionization detector (GC × GC-FID) or time-of-flight mass spectrometer (GC × GC-TOFMS) is a powerful tool to overcome the challenges of 1D GC, such as the resolution of unresolved complex mixture (UCM). We studied a number of Tertiary, terrigenous oils, and source rocks from the Arctic and Southeast Asia, with special focus on angiosperm biomarkers, such as oleanoids and lupanoids. Different chromatographic separation and detection techniques such as traditional 1D GC-MS, metastable reaction monitoring (GC-MRM-MS), GC × GC-FID, and GC × GC-TOFMS are compared and applied to evaluate the differences and advantages in their performance for biomarker identification. The measured 22S/(22S + 22R) homohopane ratios for all applied techniques were determined and compare exceptionally well (generally between 2% and 10%). Furthermore, we resolved a variety of angiosperm-derived compounds that co-eluted using 1D GC techniques, demonstrating the superior separation power of GC × GC for these biomarkers, which indicate terrigenous source input and Cretaceous or younger ages. Samples of varying thermal maturity and biodegradation contain higher plant biomarkers from various stages of diagenesis and catagenesis, which can be directly assessed in a GC × GC chromatogram. The analysis of whole crude oils and rock extracts without loss in resolution enables the separation of unstable compounds that are prone to rearrangement (e.g. unsaturated triterpenoids such as taraxer-14-ene) when exposed to fractionation techniques like molecular sieving. GC × GC-TOFMS is particularly valuable for the successful separation of

  20. Organic geochemical study of domanik deposits, Tatarstan Republic.

    Science.gov (United States)

    Nosova, F. F.; Pronin, N. V.

    2010-05-01

    in reducing environments. Mass chromatograms show the distribution of regular steranes, iso-steranes, lower molecular weight C21 and C22 steranes (pregnanes) (m/z 217) and triterpanes (m/z 191). The biomarkers distribution of the domanic samples generally suggests a major marine phytoplankton contribution relative to terrigenous land plant source input. The marine affinity is evident from the relatively abundant C27 steranes, which are biomarkers for marine algal contribution to organic matter and low C29 sterane contens. In this present study, samples are dominated by 5α, 14α, 17α (H)-20R and 5β, 14α, 17α (H)-20R steranes (biological configuration). The ratios of 20S/(20S+20R) for αααC29 steranes and ββ/(αα + ββ) for 5α-C29 steranes in the samples, are 0.21 to 0.55 and to 0.12 to 0.50, respectively. The thermal maturity level, assessed by values of several biomarker parameters has been estimated to be within end of diagenesis/eginning of catagenesis and correspond to theoretical vitrinite values (R0) in the range 0.57-0.65%.

  1. Résines et asphaltènes : évolution en fonction des types de matière organique et de leur enfouissement Resins and Asphaltenes: Evolution As a Function of Organic-Matter Type and Burial

    Directory of Open Access Journals (Sweden)

    Castex H.

    2006-11-01

    several basins. It was shown that: (a Resins have higher mean carbon and hydrogen values as well as a lower C/H ratio than asphaltenes. Resins thus have a more aliphatic and or more alicyclic structure. On the other hand, asphaltenes contain more sulfur, oxygen end nitrogen. (b Sulfur and oxygen are not parameters enabling basins to be differentiated. (c Different types of organic matter are revealed by an H/C, O/C diagram. Their chemical evolution with burial is characterized by a decrease in hydrogen, oxygen and sulfur contents. Proton nuclear magnetic resonance (NMR and infrared spectroscopy (IRS were used to follow the structural evolution of resins and asphaltenes coming from different types of organic matter (algal, marine and terrestrial buried at increasing depths. NMR can be used to compute several structural parameters such as FA aromaticity and the degree of sigma substitution of the aromatic system. The FA factor seems to increase with burial and according to the type of organic matter, while sigma seems to decrease. These data were completed by infrared spectroscopy. The surface areas of the bands corresponding to the following functions were computed: (a OH in the 3700-2700 cm-1 range; (b carbonyl C-O around 1700 cm-1; (c aliphatic C-H at 2900, 2455 and 1380 cm-1; (d aromatic C-H at 1610 cm-1. Variations in the intensity of bands: (a decrease of aliphatic C-H and of C-O functions; (b increase of aromatic C-H and C-C are related to both the type of organic matter and its catagenesis.

  2. Cement characteristics of the Upper Carboniferous phylloid algal reef limestone in Ziyun County, Guizhou Province%贵州紫云上石炭统叶状藻礁灰岩胶结物特征

    Institute of Scientific and Technical Information of China (English)

    孙宝亮; 巩恩普; 李金梅; 关长庆; 张永利

    2012-01-01

    phylloid algal thalli had high porosity and big pores, and marine botryoidal cement and isopachous acicular cement grew in the pores. During the early diagenetic stage, cementation supplied a great amount of cements, constructed rock framework, and consequently decided the features of the limestone rock. Blocky calcite spar and calcite microspar were formed in small pores, and radiating cement fans grew in big pores. During the epidiagenetic stage, extensive dissolution and cementation occurred. Vuggy or channel porosity was created by dissolution in the recharge area, and calcite precipitation was greatly increased in downflow areas. Meteoric phreaticcements include isopachous columnar calcite and blocky or equant calcite cement. Isopachous columnar cement is volumetrically more abundant. The porosity of the reef limestone was reduced dramatically through the early-stage cementation, so the reef limestone could prevent mechanical compaction. During the middle and late diage-netic stage, nearly all porosity was occluded by cements with low rates of fluid influx and efflux, and the remaining pores were filled with isopachous bladed cement and drusy or blocky calcite spar. Some preexisting cements were altered during the middle or late diagenetic stage, the color of isopachous bladed to columnar calcite cement changed from gray to white, and the color of botryoidal cement became more blackish due to hydrocarbon infiltration. Some isopachous bladed to columnar calcite cement could be dissolved, leaving mouldic pores filled subsequently and radiating cement fans formed simultaneously. Construction fracturing is one of the main types of diagenesis during the catagenesis stage. Rusty microcrystalline layers containing Fe2C>3 line the wall of some fractures, and vadose pisoids and ferrugineous crystal silt containing Fe2O3 are deposited at the bottom of the cavities formed in the tectonic fractures, which indicates that they were formed in oxidizing vadose environments. Late

  3. 腮腺肿瘤改良手术切口与传统手术切口的对比分析%Comparative study between modified technique of parotidectomy and traditional technique

    Institute of Scientific and Technical Information of China (English)

    谷爱玲

    2014-01-01

    test were checked clinically .A structured questionnaire was con-structed, sensation of the ear lobe and facial contour were in cooperated into the questionnaire .The data analysis were performed using SPSS Windows version 13.0 and were assessed by t -tests and Chi square tests .Results:There was no difference between two groups in salivary fistula and tumor recurrence(P >0.05).In MP group,the incidence of provisional facial paralysis,gustatory sweating syndrome, sense of lobulus auriculae and prosopo -catagenesis was significantly lower than those in TP group ( p<0.05) .Conclusion:The modified in cision of parotidectomy greatly reduce the disadvantages of the traditional technique .It should be better than conventional technique .