| 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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| 引用本文： | 白悦悦,吕庆田,刘招君,Simon C GEORGE,孙平昌,孟庆涛,谢文泉,宋青磊,王君贤,徐川.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[J].地球学报,2021,42(4):501-513. |
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| 作者姓名： | 白悦悦 吕庆田 刘招君 Simon C GEORGE 孙平昌 孟庆涛 谢文泉 宋青磊 王君贤 徐川 |
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| 作者单位： | 中国地质调查局中国地质科学院地球深部探测中心;吉林大学地球科学学院;麦考瑞大学地球与行星科学系;中南大学地球科学与信息物理学院 |
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| 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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| 摘 要： | 柴达木盆地北缘鱼卡地区中侏罗统石门沟组含煤段中发育有油页岩、煤、碳质泥岩和泥岩等富有机质细粒沉积.为了研究其沉积有机相的类型及煤和油页岩形成的控制因素,本文通过岩心观察、工业分析结合有机地球化学测试分析等方法将含煤段细粒沉积物划分为了类型A(三角洲平原沉积环境)、B(三角洲前缘-浅湖沉积环境)、C1(湖沼非油页岩亚相)及C2(湖沼油页岩亚相)四种类型,其中类型C1沉积物中发育煤,类型C2中发育油页岩,且煤较油页岩具有更高的含油率、水分、挥发分以及发热量值.有机质类型特征方面,沉积有机相类型A、B及C1沉积物有机质类型均为Ⅱ2-Ⅲ型、有机质来源均以陆源和混合来源两种有机质来源为主,而类型C2中主要为Ⅱ2型,以混合有机质来源为主;类型A及C2其沉积物有机质均处于未成熟阶段,而类型B和C1中有机质均处于未成熟-低成熟阶段;有机质保存条件方面,类型A沉积物主要形成于缺氧的淡水环境,类型B主要形成于贫氧-缺氧的淡水-半咸水环境,类型C1形成于贫氧-缺氧的淡水-半咸水环境,而类型C2则主要形成于缺氧的淡水-半咸水环境.其中类型B较类型A,类型C2较类型C1,其沉积物均形成于更为还原且盐度更高的水体环境中.石门沟组含煤段是煤和油页岩的形成层位,稳定的沉积环境、丰富的湖泊有机质来源、良好的保存条件及较少的陆源碎屑的稀释共同促进了类型C2中油页岩的形成,而丰富的陆源植物供给及良好的保存条件则促进了类型C1中煤层的形成.
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| 关 键 词： | 油页岩 煤 沉积有机相 有机质特征 柴达木盆地 |
An Analysis of Sedimentary Organic Facies in the Coal-bearing Member of Middle Jurassic Shimengou Formation, Yuqia Area, Qaidam Basin |
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| Institution: | SinoProbe Center-China Deep Exploration Center, China Geological Survey & Chinese Academy of Geological Sciences;College of Earth Sciences, Jilin University;Department of Earth and Planetary Sciences, Macquare University;School of Geosciences and Info-physics, Central South University |
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| Abstract: | 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. |
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| Keywords: | oil shale coal sedimentary organic facies organic matter characteristics Qaidam Basin |
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