Showing papers in "Organic Geochemistry in 2015"

TL;DR: In this paper, the authors employ ion beam polishing and high resolution scanning electron microscopy to show that primary organic matter (OM)-hosted pores are common in thermally immature shales.

TL;DR: In this article, a suite of seven methods (elemental analysis, MIR, NEXAFS spectroscopy, 13C NMR, BPCA analysis, lipid analysis and helium pycnometry) were compared with 13 measurements from them using a diverse sample set of 38 laboratory chars.

TL;DR: The data suggest that the spatial and temporal variation in chain length distributions observed in studies of sediment archives may be driven in large part by growing season temperature and/or aridity rather than photosynthetic pathway (C3 or C4).

TL;DR: Wang et al. as mentioned in this paper analyzed the brGDGTs in soils from Mt. Shennongjia using an improved liquid chromatography method and examined whether the newly described 6-methyl brDGTs were the main cause of the large scatter in the correlation between MBT and MAT.

TL;DR: In this article, a non-pyrogenic route for the formation of condensed aromatic compounds from lignin is suggested, specifically that hydroxyl radical-initiated oxidation of Lignin can produce black carbon-like condensed aromatic compound.

TL;DR: In this paper, the authors used HP experiments to investigate the petroleum composition and quality of petroleum generated from a Brazilian lacustrine source rock containing Type I kerogen with increasing thermal maturity.

TL;DR: In this article, an integrated geochemical approach was utilized to unravel the characteristics, origin and alteration of the deep oils in the Tazhong Uplift, Tarim Basin whereas the oil source is still controversial.

TL;DR: In this article, molecular composition, bulk and individual n-alkane δ 13 C and individual alkyl-dibenzothiophene δ 34 S values were determined for the potential source rocks and for oils from Cambrian and Ordovician reservoirs to determine the sources of the oils and to address whether these values can be used effectively for oil-source rock correlation purposes.

TL;DR: The role of aquatic plants in affecting δ13C values of long chain n-alkanes in lake sediments has been considered a reliable means of tracking changes in the terrigenous contribution of plants with C3 and C4 photosynthetic pathways.

TL;DR: The relative contributions of polycyclic aromatic hydrocarbons (PAHs) from multiple natural and anthropogenic sources are not well understood, but concerns linger about bioavailability and consequent risks to marine biota as mentioned in this paper.

TL;DR: In this paper, the stable hydrogen isotope ratios of 313 natural gas samples from six of China’s sedimentary basins are used to evaluate the factors that influence the hydrogen isotopic composition of methane, which is an important parameter in natural gas research and provides complementary information to that provided by carbon isotopes.

TL;DR: In this paper, the authors examined sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment cores from Saskatchewan lakes situated ∼100-220 km east-northeast of the main area of bitumen mining activities.

TL;DR: In this paper, a modified Rock-Eval pyrolysis program, starting at lower temperature (180 °C) with a heating rate of 30 °C/min, is proposed as a standard mode for the analysis of recent organic matter (OM) in order to avoid misleading interpretation of rock-eval data and make possible the inter-comparison of results whatever the RockEval device used.

TL;DR: In this article, the carbon isotope composition (δ13C) of n-alkanes in common plants along a latitudinal gradient in C3/C4 vegetation and relative humidity in Cameroon and demonstrated that pentacyclic triterpene methyl ethers (PTMEs) and n-C29 and N-C31 in the same soil, derived mainly from C4 graminoids (e.g. grass) and C3 plants, respectively, were an effective proxy for reconstructing precipitation δD values even if plant types changed significantly.

TL;DR: In this article, the authors examined the potential of tetraethers as an indicator of local variation in sea surface temperature (SST), and collected 70 surface sediments from the Chinese coastal seas (CCSs) including 16 from the Yangtze Estuary, to determine their tetrahet lipid composition.

TL;DR: The saturated and unsaturated hydrocarbons of two samples (HD-19 and HD-21) from the same section of the Middle Eocene lacustrine Huadian oil shale in NE China were identified and shown to be mainly from algal and bacterial sources.

TL;DR: In this paper, negative-ion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize the acidic and neutral NSO compounds in a series of Duvernay-sourced oils in Canada, which are believed to have migrated extensively over relatively long distances such as along the Rimbey-Meadowbrook reef trends.

TL;DR: While leaf wax hydrogen isotopic ratio values in general followed similar trends to corresponding leaf water, a significant reduction in hydrogen isotopy fractionation at the base of leaves was found, most pronounced for Dactylis glomerata.

TL;DR: In this article, the effects of photodegradation on the molecular size distribution and composition of dissolved black carbon (DBC) were explored using a surface water dissolved organic matter (DOM) sample from a terrigenous-influenced, fire-impacted Everglades area canal.

TL;DR: In this paper, a high resolution record of branched and isoprenoid glycerol dialkyl glycerols tetraethers (brGDGTs) concentrations and distributions from a peat core from the Tibetan Plateau that spans the last 13kyr was presented.

TL;DR: In this article, coupled gas chromatography was applied to measure the compound-specific sulfur isotopic compositions of volatile organosulfur compounds over a 6 m core of anoxic Cariaco Basin sediments.

TL;DR: In this paper, it was shown that TSR may have destroyed more than 90% of the original methane charge in the most extreme instance, and the possibility that methane may be completely destroyed by TSR has important implications for deep gas exploration and the origin of gases rich in nitrogen as well as hydrogen sulfide.

TL;DR: In this article, a case study of three Sinian-Paleozoic paleo-oil reservoirs from Yunan and Guizhou provinces, South China, is presented to provide further understanding of the relationship between migrated hydrocarbons and source rocks under highly mature conditions.

TL;DR: In this paper, Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICRMS) analysis of a variety of soil and char leachates showed that a significant proportion of DBC compounds contained one or more nitrogen atoms.

TL;DR: In this article, the abnormal abundance of pregnane and homopregnane in ancient sediments and petroleum remains unresolved, and the results showed that higher pregnane levels relative to the regular steranes were observed in different petroleum basins in China.

TL;DR: In this paper, the authors analyzed brGDGTs in 27 soil samples along the 400mm isoline of mean annual precipitation in China by using tandem 2D liquid chromatography.

TL;DR: In this article, the carbon number distribution of n -alkanes from leaf waxes and their carbon isotopic composition were analyzed for the rainforest and the savannah of southwestern Africa.

TL;DR: The Arcachon Bay (France) was used as an example of a complex coastal system sheltering a wide diversity of sedimentary organic matter (SOM) sources as mentioned in this paper.

TL;DR: In this article, the use of rare earth elements (REE) for oil-source correlation has not yet been established, and the authors used traditional correlation approaches, including biomarkers and trace elemental ratios, to identify the source rock of oil sands using isolated organic extracts of mudstones and oil sands, and by analyzing the organic extracts and their corresponding whole rock material for REE compositions by inductively coupled plasma-mass spectrometry (ICP-MS).

TL;DR: In this paper, the influence of thermal maturation, multiple charges and mixing, and thermochemical sulfate reduction (TSR) on the relative distributions of alkyldibenzothiophenes (DBTs) vs alkylphenanthrenes, which are widely used to interpret depositional environment and lithology, was quantitatively analyzed by gas chromatography-mass spectrometry.