Organic matter accumulation mechanisms in the Wufeng-Longmaxi shales in western Hubei Province, China and paleogeographic implications for the uplift of the Hunan-Hubei Submarine high

Li, Shizhen; Zhou, Zhi; Nie, Haikuan; Mu, Lan; Meng, Fanyang; Shen, Bin; Zhang, Xiaotao; Wei, Siyu; Xi, Zhaodong; Zhang, Shousong

doi:10.1016/j.coal.2023.104223

Cited by 8 publications

(10 citation statements)

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“…As a result, terrestrial input was increased rapidly to dilute organic carbon content, as confirmed by high Al, K, Fe, Zr, and Ti contents and low TOC content (Figure 7). Furthermore, aluminosilicate can regulate the burial rate of organic matter through adsorbing organic matter, the transport flux of which can affect organic matter concentration [45,67,[70][71][72]. Hence, redox conditions and terrigenous inputs are important controlling factors for organic matter enrichment in the study area, followed by paleoproductivity.…”

Section: Main Controlling Factors Of Organic Matter Accumulationmentioning

confidence: 99%

“…During the Early Rhuddanian stage, the global temperature rose rapidly; as a result, glacier melting in Gondwana led to rapid transgression, and the sedimentation of TST occurred in the deepwater shelf (Figures 5-9, [71][72][73][74]. At that time, the Luzhou area was characterized as an isolated sag, with a sedimentary depocenter located in the southern part of the Luzhou area, where shale thickness reached up to 42 m [4,15,36].…”

Section: Paleoenvironmental Evolutionary Modelmentioning

confidence: 99%

“…Rapid glacier melting resulted in a sea level at this period that was higher than that at the Wufeng period, connecting water bodies between the middle Yangtze and the Qinling ocean (Figures 8 and 9, [75][76][77]). Increasing water depth at low latitude led to anoxic water in the upper Yangtze, which was helpful in enhancing the water circulation and anoxic conditions in the bottom water along the continental shelf, and promoted the occurrence of upwelling (Figures 5 and 6, [71][72][73][74]). Meanwhile, the continuously rising ocean current brought with it many nutrients (Fe, Si, and P, Figure 2, [71][72][73][74]).…”

Section: Paleoenvironmental Evolutionary Modelmentioning

confidence: 99%

“…Increasing water depth at low latitude led to anoxic water in the upper Yangtze, which was helpful in enhancing the water circulation and anoxic conditions in the bottom water along the continental shelf, and promoted the occurrence of upwelling (Figures 5 and 6, [71][72][73][74]). Meanwhile, the continuously rising ocean current brought with it many nutrients (Fe, Si, and P, Figure 2, [71][72][73][74]). The improved productivity of the ocean surface accelerated the consumption of dissolved oxygen in the bottom water, further aggravating anoxic conditions in the bottom water (Figure 4, [71][72][73][74]).…”

Section: Paleoenvironmental Evolutionary Modelmentioning

confidence: 99%

“…Meanwhile, the continuously rising ocean current brought with it many nutrients (Fe, Si, and P, Figure 2, [71][72][73][74]). The improved productivity of the ocean surface accelerated the consumption of dissolved oxygen in the bottom water, further aggravating anoxic conditions in the bottom water (Figure 4, [71][72][73][74]). Under this condition, biological remains and silica skeletons were rapidly settled and preserved under anoxic-euxinic environments, widely developing organic-rich siliceous shale (Figure 13).…”

Section: Paleoenvironmental Evolutionary Modelmentioning

confidence: 99%

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Relative Sea-Level Fluctuations during Rhuddanian–Aeronian Transition and Its Implication for Shale Gas Sweet Spot Forming: A Case Study of Luzhou Area in the Southern Sichuan Basin, SW China

Zhou,

Zhu,

Zhu

et al. 2023

JMSE

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Most scholars believe that transgression events can contribute positively to organic matter enrichment and shale gas sweet spot development, while whether or not regression events are conducive to shale gas sweet spot development remains to be further discussed. Variations in organic carbon content (TOC), and major and trace elements at the Rhuddanian–Aeronian stage in the Luzhou area, the southern margin of Sichuan Basin, were analyzed in this paper. We discuss differences in paleoenvironment organic matter enrichment and shale sweet spot development during transgression and regression. A transgressive system tract (TST) occurred during the early Rhuddanian stage, while early highstand system tracts (Ehst-1 and Ehst-2) occurred during the late Rhuddanian stage and Aeronian stage, and a late highstand system tract (LHST) developed during the late Aeronian stage. A rise in sea level during the TST in the upper Yangtze resulted in an anoxic environment, where a continuous upwelling current brought about a large number of nutrients in the seawater, significantly increasing paleoproductivity. Strong tectonic subsidence, weak chemical weathering, and a rising sea level together led to a low terrigenous debris supply in the catchment area. Therefore, paleoproductivity and redox conditions were the primary controlling factors of organic matter enrichment at the TST stage, with a clastic supply of secondary importance. With the advance of the Guangxi orogeny, the organic matter enrichment at the EHST-1, EHST-2, and LHST stages was mainly controlled by redox conditions and debris supply. A comparison of the key physical parameters and geochemical indicators of shale reservoirs from these four system tracts suggests that two shale sweet spot types (type I and II) were developed during the Rhuddanian–Aeronian stage, occurring in the TST and EHST-2 stages. High TOC and high microcrystalline quartz content are key to developing type I sweet spots, while enhanced anoxic conditions in the bottom water caused by ephemeral, small-scale sea level rises are the main determinant of class II sweet spots in the later EHST stage.

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