Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting
The transitional shale of the Permian Shanxi Formation is an important source rock for shale gas, tight sandstone gas, and coalbed methane in the Ordos Basin. This study takes third Sub-Member of Shanxi Formation as an example, and uses continuously collected shale core samples and matching geochemi...
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Frontiers Media S.A.
2025-01-01
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2024.1384098/full |
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| author | Hongzhan Zhuang Hongzhan Zhuang Yuqiang Jiang Yuqiang Jiang Xingtao Li Chan Jiang Shuxin Li Zhanlei Wang Zhanlei Wang |
| author_facet | Hongzhan Zhuang Hongzhan Zhuang Yuqiang Jiang Yuqiang Jiang Xingtao Li Chan Jiang Shuxin Li Zhanlei Wang Zhanlei Wang |
| author_sort | Hongzhan Zhuang |
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| description | The transitional shale of the Permian Shanxi Formation is an important source rock for shale gas, tight sandstone gas, and coalbed methane in the Ordos Basin. This study takes third Sub-Member of Shanxi Formation as an example, and uses continuously collected shale core samples and matching geochemical data to restore the paleo-environmental conditions of its depositional period, clarify the formation mechanism of organic rich shale in different sedimentary environments under transitional facies background. According to different types of cross-plot patterns, paleo-weathering, provenance sources, and tectonic backgrounds were determined in this study. The results indicate that Shanxi organic-rich shale can be divided into two categories: estuarine shale in Unit 1 and lagoon shale in Units 2–4. The average TOC value of estuarine shale is significantly higher than that of lagoon shale, reaching 5.55%. Estuarine shale is mainly deposited in an suboxic-anoxic bottom water environments, with high surface seawater productivity, which is conducive to the formation and preservation of a large amount of organic matter. Lagoon shale is mainly composed of Type II2 and III kerogen, with a weakly oxic bottom water environment and low water surface paleo-productivity. The organic matter mainly comes from terrigenous plant debris, and its high sedimentation rate can effectively accumulate and preserve it. The chemical weathering indicators of Shanxi transitional shale are controlled by sedimentary recycling, hydrodynamic sorting, and diagenetic alteration, and the influence of changes in the source area is relatively small. The Shanxi transitional shale is mainly deposited on the active continental margin under collision background, and its source is mainly granodiorite from the Qinling orogenic belt. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
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| spelling | doaj-art-54c00d9911a9496a9e9a8e6999df38652025-01-07T06:40:12ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632025-01-011210.3389/feart.2024.13840981384098Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic settingHongzhan Zhuang0Hongzhan Zhuang1Yuqiang Jiang2Yuqiang Jiang3Xingtao Li4Chan Jiang5Shuxin Li6Zhanlei Wang7Zhanlei Wang8School of Geoscience and Technology, Southwest Petroleum University, Chengdu, ChinaThe Unconventional Reservoir Evaluation Department, PetroChina Key Laboratory of Unconventional Oil and Gas Resources, Chengdu, ChinaSchool of Geoscience and Technology, Southwest Petroleum University, Chengdu, ChinaThe Unconventional Reservoir Evaluation Department, PetroChina Key Laboratory of Unconventional Oil and Gas Resources, Chengdu, ChinaPetroChina Coalbed Methane Company, Beijing, ChinaExploration Division, PetroChina Southwest Oil and Gas Field Company, Chengdu, ChinaPetroChina Coalbed Methane Company, Beijing, ChinaSchool of Geoscience and Technology, Southwest Petroleum University, Chengdu, ChinaThe Unconventional Reservoir Evaluation Department, PetroChina Key Laboratory of Unconventional Oil and Gas Resources, Chengdu, ChinaThe transitional shale of the Permian Shanxi Formation is an important source rock for shale gas, tight sandstone gas, and coalbed methane in the Ordos Basin. This study takes third Sub-Member of Shanxi Formation as an example, and uses continuously collected shale core samples and matching geochemical data to restore the paleo-environmental conditions of its depositional period, clarify the formation mechanism of organic rich shale in different sedimentary environments under transitional facies background. According to different types of cross-plot patterns, paleo-weathering, provenance sources, and tectonic backgrounds were determined in this study. The results indicate that Shanxi organic-rich shale can be divided into two categories: estuarine shale in Unit 1 and lagoon shale in Units 2–4. The average TOC value of estuarine shale is significantly higher than that of lagoon shale, reaching 5.55%. Estuarine shale is mainly deposited in an suboxic-anoxic bottom water environments, with high surface seawater productivity, which is conducive to the formation and preservation of a large amount of organic matter. Lagoon shale is mainly composed of Type II2 and III kerogen, with a weakly oxic bottom water environment and low water surface paleo-productivity. The organic matter mainly comes from terrigenous plant debris, and its high sedimentation rate can effectively accumulate and preserve it. The chemical weathering indicators of Shanxi transitional shale are controlled by sedimentary recycling, hydrodynamic sorting, and diagenetic alteration, and the influence of changes in the source area is relatively small. The Shanxi transitional shale is mainly deposited on the active continental margin under collision background, and its source is mainly granodiorite from the Qinling orogenic belt.https://www.frontiersin.org/articles/10.3389/feart.2024.1384098/fulltransitional shaleorganic matter accumulationpaleo-weatheringprovenancetectonic settingOrdos Basin |
| spellingShingle | Hongzhan Zhuang Hongzhan Zhuang Yuqiang Jiang Yuqiang Jiang Xingtao Li Chan Jiang Shuxin Li Zhanlei Wang Zhanlei Wang Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting Frontiers in Earth Science transitional shale organic matter accumulation paleo-weathering provenance tectonic setting Ordos Basin |
| title | Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting |
| title_full | Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting |
| title_fullStr | Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting |
| title_full_unstemmed | Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting |
| title_short | Geochemical characteristics and organic matter accumulation mechanism of the Permian Shanxi Formation transitional shale, eastern Ordos Basin: implications for paleo-weathering, provenance and tectonic setting |
| title_sort | geochemical characteristics and organic matter accumulation mechanism of the permian shanxi formation transitional shale eastern ordos basin implications for paleo weathering provenance and tectonic setting |
| topic | transitional shale organic matter accumulation paleo-weathering provenance tectonic setting Ordos Basin |
| url | https://www.frontiersin.org/articles/10.3389/feart.2024.1384098/full |
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