Factors controlling organic-matter accumulation in the Upper Ordovician-Lower Silurian organic-rich shale on the northeast margin of the Upper Yangtze platform: Evidence from petrographic and geochemical proxies

Shang, Fuhua; Zhu, Yanming; Hu, Qinhong; Wang, Yan; Li, Yang; Wu, Li; Liu, Ruiyin; Gao, Haitao

doi:10.1016/j.marpetgeo.2020.104597

Cited by 23 publications

(9 citation statements)

References 81 publications

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“…The crushed whole rock sample (100 mg) was weighed and treated with 5% HCl for 24 h. During the reaction, carbon dioxide was released, and the inorganic carbon component was removed. Then, the total organic carbon was converted into carbon dioxide by combustion in high-temperature oxygen flow, and the organic carbon content was detected and tested by an infrared detector. − …”

Section: Sample Selection and Experimental Methodsmentioning

confidence: 99%

Control of Complex Structural Deformation and Fractures on Shale Gas Enrichment in Southern Sichuan Basin, China

Shi

Tang

Wu³

et al. 2022

Energy Fuels

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The research on the differential enrichment mechanism of shale gas under the complex tectonic background is a key problem to be solved currently. The southern Sichuan Basin is taken as the research object, and the geochemical experiment, overburden porosity and permeability experiments, direction test of a ground stress experiment, and seismic interpretation method are used to clarify the structural deformation characteristics and fault characteristics under different structural styles and structural parts and summarize the differences of shale gas preservation critical conditions in different structural units. The results show that (1) the fracture level controls the boundary and scale of shale gas reservoirs. The primary/secondary faults within 3 km greatly influence shale gas reservoirs, and the complex combination of fault systems will cause obvious indigenous damage to shale gas reservoirs. (2) The angle between the fault strike and the direction of the maximum principal stress determines the sealing of the fault, and the angle greater than 45° can effectively inhibit the loss of shale gas. (3) The coupling effect of burial depth and dip angle controls the migration of shale gas along the strata. The greater the burial depth and the smaller the dip angle, the better the page sealing and preservation conditions. Based on the enrichment factors of shale gas in different tectonic units, three enrichment models of syncline, anticline, and slope are established, and the enrichment favorable areas are optimized, which has important guiding significance for shale gas exploration and development in Sichuan Basin.

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Section: Sample Selection and Experimental Methodsmentioning

confidence: 99%

Control of Complex Structural Deformation and Fractures on Shale Gas Enrichment in Southern Sichuan Basin, China

Shi

Tang

Wu³

et al. 2022

Energy Fuels

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“…While Mo is consumed and cannot be obtained in seawater, the Mo/TOC ratio of sediments also decreases accordingly. Therefore, the Mo-TOC cross-plot of sediments can be used to determine the degree of water mass restriction in sedimentary basins [58][59][60][61]. As shown in the Mo-TOC cross-plot (Figure 5), samples from the Wufeng-Longmaxi Formation in the three areas are mostly located between trend lines of the Saanich Inlet and Black Sea, indicating a weak-moderate water mass restriction.…”

Section: Water Massmentioning

confidence: 99%

The Sedimentary Geochemical Characteristics and Geological Significance of the Wufeng-Longmaxi Formation Accumulation of Organic Matter Black Shale on the Southeastern Sichuan Basin, China

2022

Geofluids

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At present, the understanding of the sedimentary paleoenvironment and organic matter enrichment law of black shale in the Wufeng-Longmaxi Formation is still insufficient. This time, we investigated the total organic carbon (TOC) content, X-ray diffraction mineralogical composition, and the major and trace element abundances of the newly recovered cores of three shale gas exploration wells in Changning, Qianjiang, and Xiushan areas which were, respectively, selected to discuss and compare the varying paleoenvironmental conditions and the factors that control organic matter accumulation, such as terrigenous input, redox conditions, primary productivity, and the degree of water retention in the basin. The results show that black siliceous shale lithofacies, gray-black shale lithofacies, gray-black silty shale lithofacies, gray argillaceous siltstone lithofacies, and gray shell marl lithofacies are mainly deposited in the Wufeng-Longmaxi Formation in the southeastern Sichuan Basin. Organic-rich black shale is mainly concentrated in the lower part of the Wufeng Formation and Longmaxi Formation. The continuous thickness of organic carbon content greater than 2% in the Changning area is 32 m, the continuous thickness in the Qianjiang area is 22 m, and the continuous thickness in the Xiushan area is 11 m. The hydrocarbon generation potential gradually weakens from west to east. The identification of the geochemical behavior characteristics of major and trace elements shows that enrichment of the organic matter black shale section in the Changning-Qianjiang-Xiushan areas is mainly formation in the anoxic-moderate water mass restriction environment with high primary productivity and less terrigenous detritus input under the low hydrodynamic conditions. However, the correlations of terrigenous detrital proxies Ti/Al, redox proxies V/Cr, Ni/Co, and paleoproductivity proxies Babio with the TOC contents show that the Changning area is a favorable area for the formation of organic-rich black shale and the Qianjiang area is affected by the Wuling underwater uplift; the thickness of the black shale deposits becomes thinner; the Xiushan area is adjacent to the Xuefeng uplift, and the deposition conditions of the accumulation of organic matter black shale deteriorate, which is unfavorable for shale gas exploration.

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“…The bedded chert samples are all plotted in the upwelling zone of the Co × Mn vs. Cd/Mo diagram (Figure 10). This is because the sediments of upwellings are generally featured by high Cd/Mo values and low Co × Mn values [57,58]. The high primary productivity of upwellings leads to an increase in Cd contents through the flourishing of Cd-rich plankton, in contrast to the constant contents of the less bio-sensitive Mo elements [59].…”

Section: The Formation Mechanism Of the Maokou Chertsmentioning

confidence: 99%

Origin of the Multiple-Sourced Cherts in Maokou Carbonates in Sichuan Basin, South China

Zheng

Tang

et al. 2021

Minerals

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Cherts have been thought to originate from biosilicification, terrestrial inputs and hydrothermal activity. The study of cherts is helpful in understanding the paleo-ocean environment and tectonic–sedimentary processes. Large amounts of cherts occur widely in the Maokou Formation in the Sichuan Basin, which may be largely connected to the Permian Chert Event (PCE). However, the source of silica and the formation process of cherts remain debated. Here, we analyze the petrographic and geochemical features of the cherts from the Guadalupian Maokou Formation (~268–259 Ma) in six sections in the Sichuan Basin. Two main types of cherts, nodular and bedded, are recognized in the Maokou Formation. The formation of nodular cherts was mainly affected by hydrothermal fluids, whereas the bedded cherts are mainly of biogenetic origin. The Emeishan large igneous province (ELIP) caused the activation of deep faults, accompanied by intense hydrothermal activities. Correspondingly, the cherts of significant hydrothermal origin developed near the active deep faults. The intensified hydrothermal activities may provide extra silica supplies and flourish the silica-secreting organisms by the associated volcanogenic upwellings that facilitated the enrichment of cherts. The study of Maokou cherts can help to record the volcanic- and silicon-related biological activities in the eastern Paleo-Tethys Ocean and can provide significant implications for chert enrichment in analogous settings.

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Factors controlling organic-matter accumulation in the Upper Ordovician-Lower Silurian organic-rich shale on the northeast margin of the Upper Yangtze platform: Evidence from petrographic and geochemical proxies

Cited by 23 publications

References 81 publications

Control of Complex Structural Deformation and Fractures on Shale Gas Enrichment in Southern Sichuan Basin, China

Control of Complex Structural Deformation and Fractures on Shale Gas Enrichment in Southern Sichuan Basin, China

The Sedimentary Geochemical Characteristics and Geological Significance of the Wufeng-Longmaxi Formation Accumulation of Organic Matter Black Shale on the Southeastern Sichuan Basin, China

Origin of the Multiple-Sourced Cherts in Maokou Carbonates in Sichuan Basin, South China

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