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30th International Meeting on Organic Geochemistry (IMOG 2021)
- Conference date: September 12-17, 2021
- Location: Online
- Published: 12 September 2021
21 - 40 of 279 results
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MOLECULAR BIOMARKERS IN FOSSIL AND MODERN CARNIVOROUS COPROLITES
Authors C. Gauthier, J. Jacob and J. BrugalSummaryWe here present new results on biomarkers preserved in fossil and modern coprolites from carnivorous animals
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FIRST INSIGHTS INTO ORGANIC GEOCHEMISTRY OF THE LATE NEOPROTEROZOIC KHARAYUTEKH FORMATION, NORTHEASTERN SIBERIA
Authors T. Parfenova and D. MelnikSummaryThe results of the first geochemical investigation of the organic matter from the Late Neoproterozoic Kharayutekh Formation widely distributed in the Kharaulakh Ranges of northeastern Siberia are presented. Data shows that the Middle Kharayutekh Member can be regarded as a potential source rock. Natural bitumen and/or gas deposits associated with the realisation of the hydrocarbon generative potential of the Kharayutekh rocks can be found in the Arctic region of Northeastern Siberia.
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CATAGENETIC EVOLUTION OF THE COMPOSITION AND STRUCTURE OF ASPHALTENE COMPONENTS OF ORGANIC MATTER
Authors L. Borisova and I. TimoshinaSummaryThe revealed tendency of changes in the elemental and structural-group composition of asphaltene components of the organic matter of different origins at different stages of transformation is concerned with:
- the formation of the composition and structure of OM asphaltenes occuring at the stage of diagenesis, which are largely predetermined by the initial substrate of the organic matter;
- the identified trend for polymer condensation changes in both genetic types of OM at the initial stage of thermocatalytic transformations;
- the directed process of asphaltene graphitization taking place during catagenesis, which is accompanied by a decrease in hydrogen content, an increase in the proportion of aromatic and condensed structures among them, and is characterized by a decreasing role of alkyl and cycloalkyl hydrocarbon substituents of their molecules.
A linear dependence of the change in composition and structure during thermocatalytic transformations which will make it possible to develop catagenesis grades based on the data obtained from the study of asphaltenes within the entire range of stages.
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Ecosystem and Hydroclimate Conditions from a New Early Human Site at Olduvai Gorge (AGS, BED I, 1.84 Ma)
More LessSummaryIn this study, we focus on a newly discovered Early Pleistocene archaeological site – AGS (Alberto Gómez Site) – at Olduvai Gorge in Northeast Africa to identify coeval landscape resources via a multi-proxy perspective. We explore the distribution of four major compound classes (n-alkanes, n-alcohols, n-alkanoic acids, and sterols) and leaf-wax δ13C-δD compositions of 24 paleosoil samples excavated from a 24 m2 archaeological transect at AGS. Our multi-proxy geochemical interpretations of the Olduvai Zinj-Paleolandscape at 1.89 Mya reveal that AGS was located near the river/lake margins and was dominated by C3 aquatic plants and C4 grasses. Given the mosaic patchy ecosystem across the Zinj-Paleolandscape soil horizon and the molecular fossils studied here at AGS, we hypothesize that hominins at Olduvai Gorge, 1.9 ma years ago, selected the locations for their main activities conditioned by the presence of water resources within the landscape.
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BHT-x: Constraining its Application as a Lipid Biomarker for Marine Anammox Using a Modern Water-Column Oxygen Gradient
Authors Z. Van Kemenade, L. Villanueva, E. Hopmans, P. Kraal, H. Witte, J. Sinninghe Damsté and D. RushSummaryRecently it was discovered that members of the marine anaerobic ammonium oxidizing (anammox) genus, ‘Ca. Scalindua spp.’, uniquely synthesize a stereoisomer of bacteriohopanetetrol (‘BHT-x’). The ratio of BHT-x over total BHT (ubiquitously synthesized by diverse aerobic bacteria) has been suggested as a proxy for water column anoxia. BHT-x hereby has the potential to act as a biomarker for anoxia as well as extend the sedimentary biomarker record of marine anammox. In this study, we have investigated the water column distributions of BHT-x and the BHT-x ratio in suspended particulate matter (SPM) samples at 15 stations along the large oxygen gradient in the Benguela Upwelling System (BUS). Distributions were compared to distributions of intact polar (IPL) ladderane phospholipids, ladderane fatty acids (FAs) and the presence of the Ca. Scalindua 16S rRNA gene reads. The similar distributions of BHT-x, ladderane FAs and the relative abundance of Ca. Scalindua 16S rRNA genes confirms the suitability of BHT-x as a biomarker for water column anammox in the sedimentary record of upwelling systems. Nevertheless, we suggest including the BHT-x ratio when interpreting anammox based on lipid biomarkers, as this study confirms that low abundance of BHT-x may not always reflect in situ water column anammox.
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ANALYSIS OF NON-DERIVATIZED BACTERIOHOPANEPOLYOLS USING UHPLC-HRMS2: A FURTHER STEP TOWARDS ENVIRONMENTAL LIPIDOMICS.
Authors E. Hopmans, N. Smit, R. Schwartz-Narbonne, J. Sinninghe Damsté and D. RushSummaryWe describe the analysis of non-derivatized bacteriohopanepolyols using UHPLC coupled to high resolution MS. We demonstrate the capabilities of the method by discussing the results of the analysis of a soil sample taken near an active terrestrial methane seep. We were able to identify 131 individual BHPS. We also identified tentatively identified several novel BHPs
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Organic Geochemistry and Source Rock Potential of the Bazhenov Black Shales form the West Siberian Basin, Russia
Authors L. Burnaz, A. Baniasad, A. Kalmykov, G. Kalmykov and R. LittkeSummaryThe West Siberian Basin (WSB) constitutes the largest petroleum province in Russia. The oil accumulations in the WSB are mainly sourced by the Upper Jurassic Bazhenov Formation (BF). This study aims to provide information on the geochemical and petrographic characteristics of a representative sample set of the siliceous BF black shales from the Southwest Ob region in the southwestern WSB. On 39 samples, comprehensive analyses and observations were performed, including total organic, inorganic carbon (TOC and TIC) and total sulfur content (TS) measurement, Rock-Eval pyrolysis, organic petrography and molecular geochemistry. The samples show excellent source rock potential and oil-prone source rock characteristics, mainly containing organic material that can be assigned to Type II kerogen. The black shales were deposited in a marine depositional environment with periodically anoxic conditions. The evaluation of maturity sensitive properties imply that the 39 samples are affected by varying degrees of thermal maturity covering the catagenesis stage from the onset to the end of the oil window.
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Evaluation of Anhydrosugars as a Molecular Proxy for Paleo-Fire Activity: A Case Study from Peloponnese, Greece
More LessSummaryAnhydrosugars like Levoglucosan (LVG) are produced upon incomplete combustion of cellulose, and can act as molecular markers for biomass burning. In this multi-proxy study from the Agios Floros wetland, Pelopponese, Greece, we found that wetter conditions - causing better organic matter preservation - was the dominant control on LVG concentrations. In contrast, the LVG profile was reciprocal to the microcharcoal record and to other proxy evidence for dryness, e.g. based on leaf wax hydrogen isotopes. We conclude that an approach using several proxies, both for fire, hydroclimate and vegetation change, is needed when aiming to reconstruct past biomass burning from wetland ecosystems with a strongly seasonal climate as in the Mediterranean. Our study also relates significant fire activity between 4400-2800 cal.yr BP to the Bronze Age period that saw intense human environmental interaction and climate change.
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Decoupling of temperature and hydroclimate in North China since late Miocene
More LessSummarywe separate the air temperature and hydrological records extending back six million years (Ma) on the basis of lipid biomarkers preserved in a terrestrial drill core (XA3 drill core) in North China, East Asia.
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Assessing the Impact of Magmatic Activity on Hydrocarbon Generation in the Namibe Basin (ANGOLA)
Authors E. Fiordalisi, B. Van Dongen, J. Moore, J. Hennissen, I. Sharp, R. Dixon and S. SchröderSummaryAssessing the impact of magmatic activity on source rock maturation and hydrocarbon generation is highly critical when evaluating the prospectivity of volcanically influenced sedimentary basins. An integrated organic geochemistry and petrographic study was conducted on a variety of bitumen samples and candidate source rocks from the Namibe Basin of Angola, which was affected by multiple magmatic events. Analyses suggest that multiple processes of hydrocarbon generation and emplacement took place, including locally forced thermal maturation of otherwise immature source rocks and source rock thermal maturation via conventional basin-scale burial processes. Imminent future analyses include vitrinite reflectivity and 1-D modelling to characterise the basin thermal regime and quantitatively assess the impact of magmatic activity on source rock maturation and hydrocarbon generation.
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Lipidomics of Environmental Microbial Communities
Authors S. Ding, N.J. Bale, E.C. Hopmans, L. Villanueva, M. Arts, S. Schouten and J.S. Sinninghe DamstéSummaryStructurally diverse, specialized lipids are crucial components of microbial membranes and other organelles and play essential roles in ecological functioning. The detection of such lipids in the environment can reveal not only the occurrence of specific microbes but also the physicochemical conditions to which they are adapted to. Traditionally, liquid chromatography coupled with mass spectrometry allowed for the detection of lipids based on chromatographic separation and individual peak identification, resulting in a limited data acquisition and targeted at certain lipid groups. Here, we explored a comprehensive profiling of microbial lipids throughout the water column of a marine euxinic basin (Black Sea) using ultra high-pressure liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS/MS). An information theory framework combined with molecular networking based on the similarity of the mass spectra of lipids enabled us to capture lipidomic diversity and specificity in the environment, identify novel lipids, differentiate microbial sources within a lipid group, and discover potential biomarkers for biogeochemical processes. The workflow presented here allows microbial ecologists and biogeochemists to process quickly and efficiently vast amounts of lipidome data to understand microbial lipids characteristics in ecosystems.
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PY-GC×GC-TOFMS: A POTENTIAL TOOL FOR THE MOLECULAR CHARACTERIZATION OF FOSSIL BIOPOLYMERS
Authors R. Umamaheswaran, S. Dutta and S. KumarSummaryIn recent years, there has been an increase in interest in the preservation of nitrogen-bearing biopolymers in organic remains from deep time, reflected by the increase in reports of such preservation. However, there has also been controversy regarding the veracity of these reports. Here, we propose a method to independently characterize the molecular structure of various biomacromolecules, by using pyrolysis comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (Py-GC×GC-TOFMS). We initially analyze G. Prisca, Tasmanites and fossil resin to demonstrate efficacy of this technique. We then analyze industry standards of chitin, collagen and fossil melanin to identify characteristic compound distributions and to distinguish between the three nitrogen-bearing biomacromolecules. We then apply the technique to an Eocene mammal bone.
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USING LOGGING DATA TO ESTABLISH A METHOD OF S1 CALCULATION AND EVALUATE OIL-BEARING PROPERTIES OF SOURCE ROCKS, SONGLIAO BASIN
By Z. XiaochangSummaryThe calculation model is established by using interval transit time and resistivity curves to calculate the rock pyrolysis parameter S1, so as to evaluate the oil-bearing property of source rocks. S1 of 168 wells are calculated by this method, and 71 wells of them have been measured S1 from core samples. Comparing the difference between the average value of calculated S1 and measured S1,it can be seen that the more samples measured S1 in a single well, the smaller the difference between the calculated S1 and the measured S1. By drawing several well-connected sections and S1 plans, the changing trend of oil-bearing property of source rocks in study area is definited, and the favorable oil-bearing areas are pointed out. This S1 calculation method is suitable for the oil-bearing evaluation of regional source rocks and has guiding significance for exploration.
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INFLUENCE OF CLASTIC MINERALS ON THE PHASE BEHAVIOR OF HYDROCARBON
More LessSummaryTo predict the phase state of the petroleum in these deep-buried reservoirs accurately would be of great benefit in further exploration and development. However, the influence of reservoir minerals on phase behaviors of crude oil in deeply buried reservoirs remains poorly understood. Here we report on our investigation of the influence of common siliceous minerals (quartz, feldspar, montmorillonite, illite) on the cracking and phase behavior of crude oil. We demonstrated that the common minerals found in clastic oil reservoirs have complicated influences on the thermal cracking behavior of crude oil. Further analyses showed that the PVT phase characteristics of the crude oil can also be related to the minerals present. Clay minerals, and especially montmorillonite, significantly change the dew point temperature and bubble point pressure. However, when Ro values exceed 2.0%, even when montmorillonite content reached 40 wt. %, the phase behavior of crude oil does not change significantly.
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INFLUENCE OF CARBONATE MINERALS ON THE PYROLYSIS BEHAVIOR OF HYDROCARBON
More LessSummaryThe knowledge of the influence of minerals on oil cracking behaviors will be benefit to the predicting of physical properties (such as density, viscosity and phase state) and chemical composition of petroleum. Though considerable amounts of carbonate reservoirs are dolostone reservoirs, the role of dolomite on the thermal evolution of hydrocarbons is still not well understood. To investigate the influence of dolomite, a series of laboratory simulation experiments of oil with various carbonate minerals, including calcite, magnesite, and dolomite were conducted and analysed here. This study demonstrate that two common carbonate minerals (calcite and dolomite) have different influences on the oil cracking behavior and PVT phase of oil in carbonate conditions. Calcite had limited influences on the thermal cracking behavior of crude oil, with slightly reduction of the yield of C6-13, while dolomite strongly affected the yield of C1-5, C6-13 and H2S. The presence of dolomite seems to promote the generation of H2S and the cracking of C1-5.
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Biomarker Signatures in Cretaceous Sediments of An Island Continent
Authors D. Niyolia, S. Dutta and B. SamantSummaryThe unique position of Indian plate during the Early Cretaceous draws our attention to study the paleofloral diversity on the Indian continent. An attempt has been made to investigate the distribution of biological markers of Early Cretaceous shale of Krishna Godavari (KG) Basin, Early Cretaceous coal and shale of Kutch Basin and Late Cretaceous shale from Deccan Intertrappean sediments. The terpenoid composition of Early Cretaceous samples of Kutch and KG Basin is represented by the significant occurrence of diterpenoids in both aliphatic and aromatic fractions. However, the Late Cretaceous sediments are dominated by angiosperm derived triterpenoids. Therefore, the present study clearly suggests that the angiosperms evolved in the island continent during the Late Cretaceous.
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Molecular and Isotope Composition of Biomarkers in Immature Oil Shale and its Liquid Pyrolysis Products (Open and Closed System)
Authors G. Gajica, A. Sajnovic, J. Schwarzbauer, A. Kostic, B. Jovancicevic and K. StojanovicSummaryThe molecular and isotopic composition of biomarkers in initial bitumen isolated from raw immature oil shale samples from the Lower Miocene Aleksinac Basin (Serbia) and liquid products (LPs) obtained by pyrolysis in open (OS) and closed systems (CS) are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in LPs is determined.
The molecular composition of the LPs from the OS pyrolysis is very similar to those in initial bitumen, independently on kerogen type. The LPs from the CS pyrolysis have the distributions of biomarkers similar to those in crude oils generated in an early to main stage of “oil window“. The biomarker data suggests that mixed type I/II kerogen attained slightly higher maturity level by the CS pyrolysis than type I kerogen. The isotopic signatures of n-alkanes in LPs obtained by the OS pyrolysis are isotopically lighter than in initial bitumen, independently on kerogen type, whereas in liquid products from the CS they become heavier; showing more pronounced difference for type I kerogen. The results indicate that δ13C data should be used with caution in interpretation of samples having different maturity and particularly of LPs obtained by different system pyrolysis.
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Hydrocarbons in Intertidal Deposits of the Norwegian and Russian Coast of the Barents Sea
Authors A. Kursheva, I. Morgunova, V. Petrova, I. Litvinenko, G. Batova, A. Maltseva, E. Golikova and P. RenaudSummaryThe complex study of the organic matter (OM) and HC molecular markers in sediments and soils of the Arctic littoral is an important step to the environment protection. The study of polycyclic aromatic HCs (PAHs) is of particular interest due to their toxicity and high content in the main anthropogenic pollutants (oil, fuels, combustion products etc.).
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Organic Matter in Bottom Sediments of the Shelf Part of the Laptev Sea as an Indicator of Sedimentation (Expedition 2018)
Authors I. Litvinenko, A. Kursheva, V. Petrova, G. Batova, I. Morgunova and E. GusevSummaryThe main idea was to investigate the composition of hydrocarbon (HC) molecular markers, as indicators of the origin of sedimentary material. The object of the study is bottom sediments collected from latitudinal transects stretching along the outer edge of the shelf and the upper continental slope of the Laptev Sea. Sampling was made during the research cruise of FSBI VNIIOkeangeologia in 2018 (R/V Ivan Petrov). The molecular composition of the DOM indicates a significant input of terrigenous components of diagenetic maturity degree to the sediments of the region. Moreover, the input of molecular markers characteristic for the bacterial activity (possibly methanotrophic) is detected in some sediments (n-C16 and n-C18 predominate in composition of the lower molecular weight n-alkanes; the tricyclic terpanes ratio (2(C19+С20)/(C23+С24+C25+С26) < 1). The inflow of the reduced Atlantic waters with the along-slope currents and the processes of bottom and coastal abrasion determine the contribution of the transformed marine DOM to the sediments of continental margin.
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STABLE ISOTOPE SIGNATURES FROM SUBSTRATE UTILIZATION BY DIFFERENT FUNGAL ECOTYPES VIA A DUAL-SIP APPROACH
Authors S. Jabinski, W. De Melo Rangel, F. Lorenz and T.B. MeadorSummaryEach year, roughly one-sixth of atmospheric carbon (115 Pg C) is cycled through terrestrial vegetation, channeled into the soils below, and respired back to CO2 ( IPCC, 2007 ). However, predicting the reactivity and CO2 buffering capacity of soil systems and thus the carbon-climate feedback in terrestrial ecosystems is limited by poor understanding of the accessibility and turnover of “recalcitrant” organic matter in soils ( Lehmann & Kleber, 2015 ). As major decomposers in soil ecosystems, fungi are among the few organisms on the planet that can feed on chemically stable forms of organic C ( Šnajdr et al., 2011 ; Kirk & Farrell, 1987 ) but are also known to directly access recently produced plant photosynthate ( Högberg et al., 2001 ). This study improves quantification of substrate utilization by different fungal ecotypes in order to help define the rates and controls of fungal production and the cycling of soil organic matter.
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