Organic matter accumulation mechanism and characteristics in marine-continental transitional shale: A case study of the upper Permian Longtan Formation from the Well F5 in Sichuan Basin, China

Yang, Kai; Zhang, Bing; Yao, Yongjun; Yang, Hong–Yu; Zhang, Haiquan; Xiao, Wei; Wang, Yan

doi:10.1016/j.petrol.2021.109604

Cited by 12 publications

(17 citation statements)

References 53 publications

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“…The influx of detrital materials into sedimentary basins can impact SRs, thereby influencing the efficiency of OM preservation. 26,69 Astronomical cycle analysis of the GR logging from the TY−SX sediments deposited within the time interval of 293.65−300. 64 Ma indicated SR values ranging from 2.6 to 3.9 cm/kyr, slightly higher than the SR values (1.65−1.77 cm/kyr) observed in the TY−SX sediments in the Southern North China Basin.…”

Section: Elemental Geochemistrymentioning

confidence: 99%

Geochemical Constraints and Astronomical Forcing on Organic Matter Accumulation of Marine–Continental Transitional Shale Deposits in the Qinshui Basin during the Carboniferous–Permian Transition

Lu,

Gao,

Tiong

et al. 2024

ACS Earth Space Chem.

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During the Carboniferous–Permian transition, the paleoclimate of Earth transitioned from an icehouse to a greenhouse state, severely impacting the burial patterns of organic matter (OM). Within the Upper Carboniferous–Lower Permian Taiyuan–Shanxi formations (TY–SX) in the Qinshui Basin, North China, lie a series of marine–continental transitional organic-rich shale deposits. However, the mechanism behind the enrichment of OM in these shale deposits, formed during the icehouse–greenhouse transition, remains unclear. To address this issue, a suite of transitional shale deposits was investigated by using geochemical and astronomical cyclostratigraphic analyses. The results show that the depositional age of TY–SX spans from 293.65 to 300.64 ± 0.412 Ma. The depositional environments of these TY–SX shales tended toward oxidation, with the TY shales slightly more reducing than the SX shales. The paleoclimate of the TY–SX shales suggests warm and humid environments with comparatively strong chemical weathering intensity. Primary productivity in these TY–SX shales was estimated to be low, but the influx of terrigenous detritus was robust, driving OM accumulation through terrigenous inputs. The 405-kyr astronomical cycle had a forcing effect on the paleoenvironment variations, and the 173-kyr astronomical cycle showed a covariance with OM enrichment. The TY shales exhibited a stable and moderate sedimentation rate, with enhanced terrigenous OM input leading to OM enrichment, whereas the OM contents of the SX shales, deposited under conditions of low primary productivity and oxidation, experienced dilution of the OM content owing to detrital inputs.

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Section: Elemental Geochemistrymentioning

confidence: 99%

Geochemical Constraints and Astronomical Forcing on Organic Matter Accumulation of Marine–Continental Transitional Shale Deposits in the Qinshui Basin during the Carboniferous–Permian Transition

Lu,

Gao,

Tiong

et al. 2024

ACS Earth Space Chem.

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“…Comprehensive geology of Sichuan Basin. (a) Location of Sichuan Basin; (b) paleography and location of the study area in the Sichuan Basin (reproduced with permission from ref . Copyright 2022 Elsevier); and (c) lithological column of the Permian strata (reproduced with permission from ref .…”

Section: Geological Settingsmentioning

confidence: 99%

“…In the late Permian period, due to sea level rise, coastal marshes and lagoons were widely developed in the southwestern Sichuan Basin (Figure 1b), 33 and a set of coal-bearing marine−continental transitional shale strata were deposited (Figure 1c). 34 The study area of this paper is located in the southeastern margin of the Sichuan Basin in the Lintanchang area (Figure 1b), which was mainly deposited in a lagoon environment in the late Permian.…”

Section: Geological Settingsmentioning

confidence: 99%

Depositional Environment Variation and Organic Matter Accumulation Mechanism of Marine–Continental Transitional Shale in the Upper Permian Longtan Formation, Sichuan Basin, SW China

Wang

Guo

et al. 2022

ACS Earth Space Chem.

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Marine−continental transitional shale gas exploration is one of the hottest topics in the academic and industrial community. Frequent sedimentary environment changes lead to substantial heterogeneity and complex organic matter enrichment mechanisms, and it is of great practical significance to clarify the paleoenvironment of marine−continental transitional shale and reveal the enrichment mechanism of organic matter for subsequent shale gas exploration. However, strong heterogeneity creates divergence for our understanding of organic matter enrichment mechanisms and resource potential. This paper selected the marine−continental transitional shale of the Permian Longtan Formation in the southeastern Sichuan Basin as an example. Through TOC analysis, XRD measurements, and major and trace element analyses, we identify the depositional cycle and lithofacies, characterize the paleosedimentary environments of different lithofacies, establish depositional models, and clarify the organic matter enrichment mechanism. Four lithofacies can be identified in the Longtan Formation in the study area: organic−lean carbonate shale (LC), organic−lean mixed shale (LM), organic−lean argillaceous shale (LCM), and organic−rich argillaceous shale (RCM). The terrestrial detrital influx of the LCM and RCM shales is obviously strong, while the RCM shale was deposited in a relatively dysoxic and humid environment. For the Longtan shale, the terrestrial detrital influx and redox environment determine the enrichment of organic matter. In the lagoon sediment system, due to the high terrestrial detrital influx, the argillaceous shale in the transitional shale gas system should be given more attention in future exploration. For different kinds of shale gas systems (marine, marine− continental transitional, and lacustrine), the effect of the terrestrial detrital influx is the main difference. In marine−continental and lacustrine shale gas systems, shales with high TOC values can still exist in the context of oxic sedimentary environments. The research results of this paper can provide a theoretical basis for future marine−continental transitional shale gas sweet spot prediction and exploration from geochemical perspectives.

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“…On the other side, when it is 70-85, it indicates a humid and warm climate. Although most of CIA values in El Fashn and Dabaa formations are less than 50, the weathering line shows a semihumid climate in Ghaida area shifting to semiarid conditions in Maydoum area that indicated by cross plot of Al 2 O 3 + Na 2 O + K 2 O vs. SiO 2 [25]; Figure 6). [26][27][28][29][30].…”

Section: Major and Trace Elementsmentioning

confidence: 99%

“…Figure 6: Cross plot of SiO 2 vs. sum of Al 2 O 3 + Na 2 O + K 2 O for the analyzed samples determine the conditions of deposition (after[25,48]). …”

mentioning

confidence: 99%

Assessment of Mineralogical and Geochemical Composition of Oligocene/Eocene Black Shale Deposits in Beni Suef Area, Egypt

Soliman

Salama

El-Sayed

et al. 2022

Advances in Materials Science and Engineering

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Black shale deposits are widespread in the Paleogene successions in the Beni Suef area, Egypt. In this work, the mineralogical composition, total organic carbon (TOC), and total sulfur (TS) contents of black shales were determined. The organic matter (OM), thermal maturation, and kerogen type can be determined using Rock-Eval pyrolysis. The results show that smectite and kaolinite are the dominant clay minerals in the analyzed samples. Al2O3 and SiO2 as major elements and Zr as a trace element are dominant constituents of terrigenous origin of the Dabaa and El Fashn formations. The total organic carbon content reaches 2.27 wt% at the El Fashn Formation in the Ghaida Al-Sharqia quarry but 0.36 wt% in the Oligocene Dabaa Formation in the Maydoum quarry. However, the total sulfur content reaches 0.58 wt% in the Dabaa Formation but 1.52 wt% in the El Fashn Formation. These results confirm that (1) the Dabaa Formation was formed in oxidizing environments and oxidized the high volume of OM and (2) the El Fashn Formation accumulated in reducing environments of mostly suboxic conditions. The Rock-Eval pyrolysis results of the black shale deposits reflected a kerogen type III of terrestrial origin of the El Fashn Formation due to the high OM content preservation in suboxic shallow marine environments. The Tmax and production index parameters of Rock-Eval pyrolysis reﬂected that the black shale deposits in the El Fashn Formation are immature, but with surface retorting, it can generate natural gas.

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Organic matter accumulation mechanism and characteristics in marine-continental transitional shale: A case study of the upper Permian Longtan Formation from the Well F5 in Sichuan Basin, China

Cited by 12 publications

References 53 publications

Geochemical Constraints and Astronomical Forcing on Organic Matter Accumulation of Marine–Continental Transitional Shale Deposits in the Qinshui Basin during the Carboniferous–Permian Transition

Geochemical Constraints and Astronomical Forcing on Organic Matter Accumulation of Marine–Continental Transitional Shale Deposits in the Qinshui Basin during the Carboniferous–Permian Transition

Depositional Environment Variation and Organic Matter Accumulation Mechanism of Marine–Continental Transitional Shale in the Upper Permian Longtan Formation, Sichuan Basin, SW China

Assessment of Mineralogical and Geochemical Composition of Oligocene/Eocene Black Shale Deposits in Beni Suef Area, Egypt

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