新疆库车坳陷古近系苏维依组高精度层序地层及其发育的主控因素探讨  

High-Resolution Sequence Stratigraphic Study on the Palaeogene Suweiyi Formation in Kuqa Depression of Xinjiang Region and Discussion on Its Major Controlling Factors

作　　者：刘景彦[1] 丁孝忠[2] 邱以钢[1] 刘俊[3] 纪云龙[1] 

机构地区：[1]中国地质大学能源学院,北京100083 [2]中国地质科学院地质研究所,北京100037 [3]北京大学地球与空间科学学院,北京100871

出　　处：《高校地质学报》2009年第3期318-327,共10页Geological Journal of China Universities

基　　金：国家重点基础发展规划(973)项目(2006CB202302)资助

摘　　要：库车坳陷位于塔里木盆地北缘南天山山前,古近系苏维依组沉积期为前陆盆地发育阶段,沉积了巨厚的河流-三角洲和滨浅湖碎屑岩建造。库车坳陷独特的地理位置和苏维依组野外大面积连续出露,为高精度层序地层分析和层序发育的主控因素探讨提供了有利条件。以相对易于追踪对比的水进期稳定泥岩为界,在苏维依组2个三级层序中进一步划分出10个四级层序和数十个五级层序。四级层序中发育有三角洲前缘河口坝、水下分流河道、下切水道、曲流砂坝、干盐湖等沉积。其中四级层序Pss1和Pss6中的曲流河道砂坝、下切谷充填和四级层序Pss3,Pss5,Pss8中的三角洲前缘河口坝、水下分流河道等砂体构成区内的主力储层,与上覆的浅湖泥或干盐湖膏泥岩构成良好的储盖组合。四级层序地球化学特征和准层序的叠置样式表明,高精度层序发育是构造沉降背景下气候作用、湖平面波动和沉积物源供给综合作用的结果,其中气候因素和沉积物源供给起了决定性作用。干旱和潮湿气候影响了湖平面波动,控制着层序充填和准层序叠置形式;逆冲带近端、远端与盆地中部沉积物源供给不同,决定了盆地内不同部位的层序发育样式和准层序的叠置形式不同。Kuqa depression lies at the northern margin of Tarim basin,nearby the southern Tianshan Mountain.The Palaeogene Suweiyi Formation was formed during foreland basin developing phase and thick fluvial-delta and lacustrine sediments were deposited.The unique location of Kuqa depression and the large range successive outcrops of Suweiyi Formation provide favorable room to carry out the high-resolution sequence stratigraphic study and the major controlling factors discussion.Based on the relative distinguishable flooding surface,the Suweiyi Formation is classified into ten 4thorder sequences and a number of 5thorder sequences or parasequences.The 4thorder sequence consists of incised valley fill,delta front mouth bar,prodelta,subaqueous distributary channel,evaporite salt lake and lacustrine deposits.The incised valley sandstone,delta front mouth bar sandstone and the subaqueous distributary channel sandstone of the 4thorder sequence Pss1,Pss6,Pss3,Pss5 and Pss8 comprise main reservoir beds.The characteristics of 4thorder sequences and the stacking patterns of parasequences indicate that under the tectonic subsidence background,the interplay of climate,lake level fluctuation and depositional supply controlled the development of the high order sequences.The climate and the depositional supply were the crucial factors.The aridity and the humidity effected the fluctuation of lake level and controlled the basin filling and sequence development.The difference of depositional supply of near thrust belt and far thrust belt made the depositional filling and stacking patterns of parasequences different.

关 键 词：高精度层序地层 沉积体系 主控因素 苏维依组 库车坳陷 

分 类 号：TE121.34[石油与天然气工程—油气勘探]