湘鄂西下寒武统牛蹄塘组黑色页岩发育特征及沉积环境  

Development characteristics and sedimentary environment of black shale of Lower Cambrian Niutitang Formation in western Hunan and Hubei

作　　者：梁小聪 牛杏 胡明毅[1] 黎洋 胡忠贵[1] 蔡全升[1] LIANG Xiaocong;NIU Xing;HU Mingyi;LI Yang;HU Zhonggui;CAI Quansheng(School of Geosciences,Yangtze University,Wuhan 430100,China;Research Institute of Exploration and Development,PetroChina Southwest Oil and Gas Field Company,Chengdu 610000,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]中国石油西南油气田公司勘探开发研究院,成都610000

出　　处：《岩性油气藏》2023年第4期102-114,共13页Lithologic Reservoirs

基　　金：国家自然科学基金项目“中上扬子地区下寒武统牛蹄塘组石英成因机制及对页岩储层物性的影响”(编号:42002148)资助。

摘　　要：湘鄂西地区下寒武统牛蹄塘组是我国南方页岩气勘探的重要目标。通过鄂西古城村和湘西岩屋潭2个剖面的下寒武统牛蹄塘组黑色页岩层系的岩石学特征与地球化学分析,开展了黑色页岩沉积的物源和构造背景研究,并探讨了其沉积环境。研究结果表明:(1)鄂西古城村和湘西岩屋潭2个剖面的牛蹄塘组黑色页岩沉积差异明显,古城村剖面牛蹄塘组页岩主要为泥质页岩,厚度小,底部发育少量硅质页岩;岩屋潭剖面牛蹄塘组页岩则以硅质页岩为主,厚度大,底部富集硅磷质结核及镍、钴、钒等多种金属。岩屋潭剖面的石英含量远高于古城村剖面,并且黄铁矿也更富集。(2)研究区2个剖面的黑色岩系沉积环境、物源背景与构造背景均存在明显差异。古城村剖面物源以长英质火成岩和石英质沉积岩为主,沉积于被动大陆边缘大陆架上的弱还原-弱氧化环境;岩屋潭剖面物源以长英质火成岩、石英质沉积岩和大陆拉斑玄武岩为主,并伴随热液物源的输入,沉积于被动大陆边缘大陆坡上的还原环境。(3)早寒武世,鄂西鹤峰古城村的沉积以黑色炭质页岩和灰岩为主,且有机质与硅质含量均较低,水体相对较浅,受海平面波动影响明显,为陆棚环境;湘西的沉积厚度大,有机质含量高,且由于靠近深大断裂,热液硅来源丰富,为大陆坡环境。The Lower Cambrian Niutitang Formation in the western Hunan and Hubei is an important target for shale gas exploration in southern China.Two profiles,Guchengcun in western Hubei and Yanwutan in western Hunan,were selected to carry out petrological and geochemical analysis of the black shale series of Lower Cambrian Niutitang Formation,so as to find out the provenance and tectonic background of the black shale,and analyze the sedimentary environment.The results show that:(1)The black shale deposits of Niutitang Formation in the two profiles are obviously different.The shale of Niutitang Formation in Guchengcun profile is mainly argillaceous shale with small thickness,and a small amount of siliceous shale is developed at the bottom,while the shale of Niutitang Formation in Yanwutan profile is mainly siliceous shale with large thickness,and the bottom is rich in silicophosphorous nodules,nickel,cobalt,vanadium and other metals.The quartz content of Yanwutan profile is much higher than that of Guchengcun profile,and pyrite is also more abundant.(2)There are obvious differences in the sedimentary environment,provenance background and tectonic background between the black rock series in the two profiles.The provenance of Guchengcun profile is mainly felsic igneous rocks and quartz sedimentary rocks,which were deposited in a weak reduction and weak oxidation environment on the continental shelf of the passive continental margin.The provenance of Yanwutan profile is mainly felsic igneous rocks,quartzitic sedimentary rocks and continental tholeiites,and with the input of hydrothermal provenance,it was deposited in a reducing environment on the continental slope of the passive continental margin.(3)In the Early Cambrian,the sediments of Hefeng Guchengcun in western Hubei were mainly black carbonaceous shale and limestone,with low contents of organic matters and silica,the water body was relatively shallow,and it was obviously affected by sea level fluctuations,so it was a shelf environment.However,the sedimentary thickness

关 键 词：陆棚 大陆坡 地球化学 热液硅 黑色页岩 牛蹄塘组 下寒武统 古城村剖面 岩屋潭剖面 湘鄂西 

分 类 号：TE121.1[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]