为了查明文南地区沙二下段的沉积作用类型,利用钻井取心、测井解释、重矿物分析等资料,对文南地区沙二下亚段的沉积相进行了研究,结果表明,文南地区沙二下亚段发育湖泊沉积体系。地层岩性以大段的紫红色和红色的粉砂岩、泥质粉砂岩、粉砂质泥岩和泥岩为特征,粒度分布和沉积构造反映水动力以弱的牵引流为主要特征。本次研究建立了研究区湖泊沉积体系的沉积模式,将其划分出泥滩、滩坝、砂泥混合滩、三角洲相和半深湖-深湖相,其中三角洲相序由于湖平面的频繁振荡发育不完整。研究区湖泊垂向沉积序列以由三角洲平原、滩坝、泥滩和砂泥混合滩组成的红色岩层为特征,同时对研究区的湖泊沉积体系和常规陆源碎屑湖泊沉积体系进行了比较。

To find out the sedimentation type in Wennan,Dongpu depression,the sedimentary characteristics of lower second sub-member of Shahejie formation have been studied by core observation,log interpretation,heavy mineral analysis,and so on.Results indicate the lower second sub-member of Shahejie formation develops a lacustrine sedimentary system,and the rock types of lacustrine sedimentary system include red and mauve siltstone,pelitic siltstone,silty mudstone and mudstone.The grain size distribution and sedimentary structure basically show that the type of liquid is faint tractional current.The model of the lacustrine sedimentary system of the region of interest is established,and the sedimentary system may be individed into mud flat,beach-bar,mixed mud-sand flat,delta facies,semi-deep lacustrine facies and deep lacustrine facies.Because the lake level is frequently changed,the delta facies is uncompleted.The redbeds that include mud flat,beach-bar,mixed mud-sand flat and delta plain are characteristics of the vertical sedimentary sequence.At the same time,the lacustrine sedimentary system of the region of interest and the conventional terrigenous clastic lacustrine sedimentary system are distinguished.