| 柴北缘鱼卡地区中侏罗统石门沟组含煤层段沉积有机相分析 |
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| 关键词:oil shale coal sedimentary organic facies organic matter characteristics Qaidam Basin |
| 基金项目:中国地质科学院基本科研业务费项目(编号: JKY202012; YWFBC201801);中国地质调查局地质调查项目(编号: DD20189607) |
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| An Analysis of Sedimentary Organic Facies in the Coal-bearing Member of Middle Jurassic Shimengou Formation, Yuqia Area, Qaidam Basin |
| Organic matter-rich fine-grained sediments of oil shale, coal, carbonaceous mudstone and mudstone are developed in the coal-bearing member of Middle Jurassic Shimengou Formation of Yuqia area, northern Qaidam Basin. In order to study the sedimentary organic facies and the controlling factors of coal and oil shale, the authors divided sediments in coal-bearing member into type A (delta plain sedimentary environment), type B (delta front-shallow lake sedimentary environment), type C1 (lake-marsh non-oil shale subfacies) and type C2 (lake-marsh oil shale subfacies) based on core observation, industrial analysis and organic geochemical analysis. Coal is formed in type C1 and oil shale is formed in type C2. Coal has higher oil yield, water content, volatile matter and calorific value than oil shale. Sediments in types A, B and C1 are all mainly of type II2-III organic matter types with terrestrial and mixed terrestrial and aquatic organic matter sources, whereas sediments in type C2 are of type II2 organic matter type with mixed terrestrial and aquatic organic matter sources. Organic matter in type A and C2 sediments are all in the immature stage while organic matter in type B and C1 are in the immature to low-mature stage. Type A sediments are mainly formed in anoxic freshwater environment, Type B is formed in oxygen deficient-anoxic freshwater to brackish water environment, Type C1 is formed in oxygen deficient-anoxic freshwater to brackish water environment, and Type C2 is mainly formed in anoxic freshwater to brackish water environment. Among them, sediments in type B and C2 are formed in more reduced and saline water environment than type A and C1, respectively. Stable sedimentary environment, abundant aquatic organic matter sources, good preservation conditions and less dilution of terrigenous debris promote the formation of oil shale in type C2, while abundant terrigenous plant supply and good preservation conditions promote the formation of coal seams in type C1. |
| BAI Yue-yue,LÜ Qing-tian,LIU Zhao-jun,Simon C GEORGE,SUN Ping-chang,MENG Qing-tao,XIE Wen-quan,SONG Qing-lei,WANG Jun-xian,XU Chuan.2021.An Analysis of Sedimentary Organic Facies in the Coal-bearing Member of Middle Jurassic Shimengou Formation, Yuqia Area, Qaidam Basin[J].Acta Geoscientica Sinica,42(4):501-513. |
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