京西潭柘寺地区石炭-二叠纪沉积相及沉积环境演化

Sedimentary Facies and Environmental Evolution of Permo-Carboniferous in Tanzhesi Area of Western Beijing

在野外剖面、钻孔岩心宏观沉积相分析及岩相类型的归纳总结基础上,根据各类岩相在垂向上的组合关系及在平面上的分布,识别出障壁-泻湖相、三角洲相、河流相及湖泊相等4种沉积相及其多种亚相类型,并建立了相应的垂向沉积序列。其中障壁岛-泻湖沉积相发育于本溪组—太原组中下部,三角洲沉积相对应于太原组上部—山西组,河流沉积相主要发育于下石盒子组—红庙岭组,湖泊沉积相发育于双泉组。研究区总体上沉积环境有从海到陆的演化过程,古气候有从温暖潮湿到相对炎热干燥的变化,聚煤作用发生于气候温暖潮湿的本溪组、太原组和山西组沉积期,在下石盒子组、红庙岭组及双泉组沉积期由于气候相对干旱,区内聚煤作用停止,没有发育煤层。

This paper analyses the sedimentary facies and lithofacies types of the Permo - Carboniferous in the Tanzhesi area, western Beijing, based on the outcrop and borehole sections. According to vertical lithofaeies combination and lateral distribution, four sedimentary facies were identified, including barrier - laggonal and lacustrine facies. The corresponding sub -facies and vertical facies sequences were recognized , deltaic, fluvial, The barrier - lagoon facies were developed in the Benxi Formation and lower part of Taiyuan Formation, the lower delta plain sub - facies were developed in the upper part of Taiyuan Formation, the upper delta plain subfacies were developed in the Shanxi Formation, the fluvial facies representing alluvial plain environment were found in the Xiashihezi Formation and Hongmiaoling Formation, and the fluvial -lucastrine facies was developed in the Shuangquan Formation. In overall, the research area has experienced the variation from marine to continental environments, and its palaeoclimates changed from warm and humid to hot and semi - arid. The coal accumulation was favored by warm and humid palaeo- climates during deposition of the Benxi, Taiyuan, and Shanxi Formations, while it was stopped by the hot and semi - arid palaeoclimates during the Xiashihezi, Hongrnaioling and Shuangquan Formations.