Geochemistry and organic petrology of the permian whitehill formation, Karoo Basin (RSA) and the Devonian/Carboniferous shale of the Appalachian Basin (USA)

Chabalala, Vongani; Wagner, Nicola J.; Malumbazo, N.; Eble, Cortland F.

doi:10.1016/j.coal.2020.103612

Cited by 11 publications

(13 citation statements)

References 30 publications

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“…Geochemical characteristics of the studied coal-bearing deposits of the 'Gubakha-Stary Most' section (namely layer 19; Fig. 4; see also Table 1) has many features in common with other coal deposits around the world (see e.g., Chabalala et al, 2020), which can be explained by the effects of neighboring marine paleoenvironments. This FPS-profile can be interpreted as a kind of weakly developed swampy hydromorphic soil (histosoil or histosol).…”

Section: Lower Carboniferous Fps-profiles Of the Kizel Coal Basinmentioning

confidence: 98%

Peat Accumulation and Early Carboniferous Environments of the Kizel Coal Basin, the Urals, Russia

Naugolnykh

2022

Acta Geologica Sinica (Eng)

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The lithological and geochemical composition and conditions of formation of the coal‐bearing deposits of the Kizel Coal Basin in the Perm region of the Urals (central Russia) are described using the two most representative sections, Gubakha–Stary Most and Krestovaya Mountain, based on a detailed “layer‐by‐layer” technique. Brief characteristics of the Lower Carboniferous paleosols from fossil paleosol (FPS‐) profiles of the studied region are given. Special attention is paid to the parent vegetation of the coal‐forming processes, based on an analysis of both plant macrofossils and palynoflora. The peat accumulation in conditions of permanent incoming of clastic material from the Paleo‐Urals to the Kizel Basin was probably effective only in more or less stable environments, when the accumulated organic matter produced by plant mortmass was not dissolved by clastic particles. Thus, the conditions of coal‐forming are reconstructed as a forest swamp, where the main dominants are represented by lycopodiopsids of the order Lepidodendrales, predominantly Lepidodendron veltheimii. These plants in particular were the source of the initial organic matter for the peat (and later coal) of the Kizel Coal Basin.

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Section: Lower Carboniferous Fps-profiles Of the Kizel Coal Basinmentioning

confidence: 98%

Peat Accumulation and Early Carboniferous Environments of the Kizel Coal Basin, the Urals, Russia

Naugolnykh

2022

Acta Geologica Sinica (Eng)

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“…Iron ions play a vital role in organic matter deposition, with higher iron ions associated with organic matter enrichment and preservation. , Studies of the size of framboidal pyrite and TOC indicated that framboidal pyrite plays a significant role in promoting organic matter enrichment. − Based on the formation period and the developmental mechanism, sedimentary pyrite in shale are categorized into three types: syn-sedimentary, diagenetic, and postfilling pyrite. − Pyrite in different morphologies is found in lacustrine shales, including framboidal, spherulitic, layered, nodular, euhedral, and anhedral pyrites. Understanding the formation stages of these different pyrite forms is crucial to investigate whether they can serve as indicators of organic matter enrichment.…”

Section: Introductionmentioning

confidence: 99%

“…Framboidal pyrite is generally considered to have formed during syn-sedimentary and early diagenetic stages, with a small grain size and negative sulfur isotopes. In contrast, spherulitic, euhedral, and anhedral pyrites may have formed during diagenesis when framboidal pyrite microcrystals increase in size or directly crystallize in sulfur-bearing waters when the concentration of reactive iron is low, with a large grain size and negative sulfur isotopes. ,− In addition, Taotao et al (2018) used scanning electron microscopy (SEM) to determine that type I and type II organic matter constituted an organic/pyrite complex with framboidal pyrite, forming a group around pyrite in the core as a whole, which was conducive to liquid hydrocarbon enrichment. In contrast, type III organic matter mostly appeared as contours and framboidal pyrite was rare .…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, the distribution of pyrite in marine organic-rich shale has become an indicator for shale oil and gas enrichment areas, with good results in the Barnet Shale of Fort Worth Basin, North America, and the Longmaxi Formation in the Jiaoshiba, Weiyuan, Wulong, and Pengshui areas of the Sichuan Basin, China. ,,, Jingwei et al. (2013) observed the presence of asphaltene molecules on the surface of pyrite using atomic force microscopy.…”

Section: Introductionmentioning

confidence: 99%

“…10 , 11 Studies of the size of framboidal pyrite and TOC indicated that framboidal pyrite plays a significant role in promoting organic matter enrichment. 12 − 14 Based on the formation period and the developmental mechanism, sedimentary pyrite in shale are categorized into three types: syn-sedimentary, diagenetic, and postfilling pyrite. 15 − 19 Pyrite in different morphologies is found in lacustrine shales, including framboidal, spherulitic, layered, nodular, euhedral, and anhedral pyrites.…”

Section: Introductionmentioning

confidence: 99%

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Pyrite Characteristics in Lacustrine Shale and Implications for Organic Matter Enrichment and Shale Oil: A Case Study from the Triassic Yanchang Formation in the Ordos Basin, NW China

Zhou,

Liu,

et al. 2024

ACS Omega

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Pyrite is widely distributed in lacustrine shales and has become a research focus in unconventional oil and gas exploration. Pyrite morphology is useful for identifying different types of organic matter and assessing shale oil enrichment in organic-rich shale. Abundant pyrite is developed in the source rocks from the Chang 7 Member of the Yanchang Formation in the Ordos Basin, NW China. However, the relationship between different pyrite types and the differential enrichment of shale oil still needs to be clarified. The organic geochemistry, petrology, and isotopic composition of the Chang 7 Member samples were analyzed. The significance of pyrite types and sulfur isotopic compositions as indicators of depositional environments and shale oil enrichment was emphasized. The Chang 7 shales contain three pyrite morphologies, framboidal pyrite (type A), spherulitic pyrite (type B), and euhedral and anhedral pyrite (type C), and their aggregates. The sulfur isotopic compositions of pyrite (δ 34 S py ) in Chang 7 shales with different pyrite types exhibited regular patterns. The δ 34 S values of types A, B, and C pyrites were sequentially positive overall (average values are −2.739, 2.201, and 7.487‰ in sequence), indicating that type A pyrite was formed during the syn-sedimentary to early diagenetic stage and types B and C pyrites were formed during the early to middle diagenetic stage. Types A, B, and C pyrites showed sequentially increasing kerogen type index values and kerogen carbon isotope values (mean values of −31.59, −28.70, and −26.45‰, successively), indicating that the horizons where types A, B, and C pyrites developed correspond to types I, II, and III organic matter, respectively. Strong correlations between the pyrite content and oil components reveal that pyrite indicates shale oil enrichment. Moreover, variations in pyrite type significantly influenced the enrichment behavior of shale oil. Types A and B pyrites contributing to reservoir space showed shale oil enrichment. They promoted saturated hydrocarbon enrichment at >15% pyrite content, whereas type C pyrite did not indicate shale oil enrichment. These findings provide new insights into the differential enrichment of organic matter and shale oil and valuable guidance for the large-scale exploration and development of shale oil resources.

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The petrology of dispersed organic matter in sedimentary rocks: Review and update

Gonçalves,

Kus,

Hackley

et al. 2024

International Journal of Coal Geology

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Geochemistry and organic petrology of the permian whitehill formation, Karoo Basin (RSA) and the Devonian/Carboniferous shale of the Appalachian Basin (USA)

Cited by 11 publications

References 30 publications

Peat Accumulation and Early Carboniferous Environments of the Kizel Coal Basin, the Urals, Russia

Peat Accumulation and Early Carboniferous Environments of the Kizel Coal Basin, the Urals, Russia

Pyrite Characteristics in Lacustrine Shale and Implications for Organic Matter Enrichment and Shale Oil: A Case Study from the Triassic Yanchang Formation in the Ordos Basin, NW China

The petrology of dispersed organic matter in sedimentary rocks: Review and update

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