Carbon isotope analysis of whole-coal and vitrinite from intruded coals from the Illinois Basin: No isotopic evidence for thermogenic methane generation

Rahman, Mohammad W.; Rimmer, Susan M.; Rowe, Harold D.; Huggett, William W.

doi:10.1016/j.chemgeo.2017.02.012

Cited by 25 publications

(5 citation statements)

References 46 publications

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“…Global events cause significant changes in sedimentary environments and lead to variations in TOC contents 25 , 62 . Hence, the mechanisms of OM enrichment and variations in the TOC content in the Da’anzhai member are discussed in this section.…”

Section: Discussionmentioning

confidence: 99%

Paleosedimentary environmental reconstruction and mechanisms of the response to the Toarcian OAE in a lacustrine shale system

Wang,

Guo,

2024

Sci Rep

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The Lower Jurassic Ziliujing Formation in China’s Sichuan Basin is a significant shale target for exploration; however, the strong heterogeneity of the properties of organic matter (OM) in shale makes it challenging to identify the target area for exploration, and the mechanism of OM enrichment is still unclear. Furthermore, the mechanisms of the response of the Da’anzhai member to the Toarcian Oceanic Anoxic Event (T-OAE) are controversial. Previous studies have focused on sedimentary facies analysis based on mineralogy and elemental abundances and have provided minimal information about organic geochemistry, which adds to the challenge of deeply understanding the influence of the T-OAE on the molecular geochemical characteristics of the Da’anzhai member. In this study, the Da’anzhai member of the Lower Jurassic Ziliujing Formation in the Langzhong area, Sichuan Basin, is studied via X-ray diffraction, total organic carbon, gas chromatography–mass spectrometry, organic carbon isotope, organic petrographical and pyrolysis analyses. To accurately identify the trend of the paleosedimentary environmental proxies, the Mann‒Kendall test is utilized to identify the trend of the data. Our results show that the Da’anzhai shale was deposited in a dysoxic transitional environment to an intermittent reducing environment with freshwater to brackish conditions. The response to the T-OAE can be identified in the middle and upper parts of the middle submember and the bottom of the upper submember of the Da’anzhai member. The T-OAE influenced the redox conditions, salinity, and OM origins during deposition in the middle of the Da’anzhai member, which resulted in the enrichment of OM. The abnormally high C30 diahopane/C30 hopane (C30D/C30H) ratio can be considered a potential proxy for locating the section of strata that responded to the T-OAE in the Da’anzhai member. In the study area, the mechanism of the response of the Da’anzhai shale to the T-OAE manifested as an improvement in hydrological cycling rather than a marine incursion. Our study provides new information that deepens the understanding of the mechanisms of the response of lacustrine shales to oceanic anoxic events from the perspective of molecular organic geochemistry.

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Section: Discussionmentioning

confidence: 99%

Paleosedimentary environmental reconstruction and mechanisms of the response to the Toarcian OAE in a lacustrine shale system

Wang,

Guo,

2024

Sci Rep

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“…The isotopic composition of organic matter and petrographic observations suggest that a significant fraction of the volatiles was redeposited within the shales. 12 C is preferentially fractionated into volatiles and pyrolysates during organic matter cracking in the contact zone, increasing δ 13 C values of the residual organic matter (Faure, 1986;Whiticar, 1996;Rimmer et al, 2005;Schimmelmann et al, 2009;Rahman et al, 2017). Thus, it is expected that the δ 13 C values of the residual organic material would become less negative in values with decreasing distance to the sills.…”

Section: The Fate Of Organic Carbon During Sill-induced Maturationmentioning

confidence: 99%

“…Thus, the flow of incipient hydrocarbon and other hydrothermal fluids from adjacent layers into aureoles likely occurred prior to significant cooling of the high-temperature environment, thereby allowing the methane to crack and become re-deposited in the form of pyrolytic carbon (Eq. ( 1); g = gas, s = solid) (Whiticar, 1996;Rimmer et al, 2005;Cooper et al, 2007;Schimmelmann et al, 2009;Rahman et al, 2017). It follows that the shales themselves may have served as a sink for generated volatiles in the form of pyrolytic carbon near the sill contacts:…”

Section: The Fate Of Organic Carbon During Sill-induced Maturationmentioning

confidence: 99%

The effects of Jurassic igneous intrusions on the generation and retention of gas shale in the Lower Permian source-reservoir shales of Karoo Basin, South Africa

Chukwuma

Tsikos

Horsfield

et al. 2023

International Journal of Coal Geology

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“…Changes seen in coals and coal-bearing sedimentary rocks can also be caused by thermal metamorphism [4,[27][28][29][30]. Coal seam No.…”

Section: Weathering and Thermally Altered Coal-bearing Depositsmentioning

confidence: 99%

The Disappearance of Coal Seams Recorded in Associated Gangue Rocks in the SW Part of the Upper Silesian Coal Basin, Poland

et al. 2021

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Coal seams in the Upper Silesian Coal Basin vanish within the Carboniferous Upper Silesian Sandstone Series and below an unconformity marking the Carboniferous top surface. Changes in the geochemical, mineralogical, petrological and palynological characteristics of gangue rocks associated with the vanished seams record what happened. The observed changes could have been caused by (1) coal-seam paleofire, (2) peat combustion, (3) igneous intrusion, (4) metasomatism and/or (5) weathering. Multifaceted research on samples collected at the Jas-Mos mining area, a part of the operating Jastrzębie-Bzie Coal Mine that are representative of different geological settings in the northern and southern parts of the mining area, point to intra-deposit paleofire as the most plausible reason for the disappearance. Biomarkers enabled recognition of differences in heating duration and oxygen access. Coal seams in the south burned quickly with abundant oxygen supply. Seams in the north pyrolyzed for an extended time under conditions of limited oxygen. Though other methods used proved less sensitive, all confirmed low (100–150 °C) paleotemperature heating. Overall, the reason for the local disappearance of the coal seams, making their exploitation difficult and unprofitable, can be assigned to a variety of different processes in a complex overlapping history of variable weathering, heating due to local endogenic fires and, probably, earlier peat combustion.

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Carbon isotope analysis of whole-coal and vitrinite from intruded coals from the Illinois Basin: No isotopic evidence for thermogenic methane generation

Cited by 25 publications

References 46 publications

Paleosedimentary environmental reconstruction and mechanisms of the response to the Toarcian OAE in a lacustrine shale system

Paleosedimentary environmental reconstruction and mechanisms of the response to the Toarcian OAE in a lacustrine shale system

The effects of Jurassic igneous intrusions on the generation and retention of gas shale in the Lower Permian source-reservoir shales of Karoo Basin, South Africa

The Disappearance of Coal Seams Recorded in Associated Gangue Rocks in the SW Part of the Upper Silesian Coal Basin, Poland

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