晚三叠世中扬子北缘前陆盆地层序地层特征及沉积演化  

Late Triassic Sequence Stratigraphy and Sedimentary Evolution of the Northern Mid-Yangtze Foreland Basin

作　　者：陈留勤[1,2] 段凯波[1] 霍荣[1] 胡水清[2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国石油天然气股份有限公司石油勘探开发研究院,北京100083

出　　处：《高校地质学报》2009年第3期328-338,共11页Geological Journal of China Universities

基　　金：中国石油化工股份有限公司海相前瞻性项目"中国南方中上扬子大陆构造与海相油气前景"(YPH08009)

摘　　要：应用沉积学和层序地层学的基本原理和方法,对中扬子北缘上三叠统4条实测露头剖面和1条测井剖面进行了详细的沉积相分析和层序地层划分,同时阐述了沉积相迁移规律、层序界面类型、层序发育特征及其控制因素。研究结果表明,该地区上三叠统可以划分为4个三级层序(TS1,TS2,TS3和TS4),进一步归为1个二级构造层序。荆门—当阳盆地上三叠统沉积厚度约为1200m,4个层序发育完整;向东至汉川、鄂州一带地层变薄不足40m,向西越过黄陵背斜至秭归、利川一带层厚100～300m,后两者保存残留不全的上三叠统只能归为1个三级层序。层序界面类型主要有不整合面、河流冲刷侵蚀作用面和岩性岩相转换面等。在露头剖面和测井剖面层序地层划分的基础上建立的层序地层格架表明,中扬子北缘晚三叠世从TS1-TS2到TS3-TS4沉积组构发生了由低能到高能的转变。在构造、古地理背景和气候因素共同控制层序发育样式的背景下,研究区经历了从湖沼体系到冲积体系的转变,体现了晚三叠世中扬子北缘前陆盆地发育早期的沉积特征。Detailed sedimentary facies analysis and sequence stratigarphic division of the four measured sections and one well log section are studied on the basis of principles and methods of sedimentolgy and sequence stratigraphy.The patterns of sedimentary facies transformation,types of sequence boundaries,sequence characteristics and their dominating factors are described as well.It shows that the upper Triassic of the northern mid-Yangtze basin can be divided into four third-order sequences（TS1,TS2,TS3 and TS4）,and further grouped into one second-order tectonic sequence.The thickness of the upper Triassic is about 1 200 m in Jingmen-Dangyang basin where the four sequences are relatively intact.In contrast,it thins westward to 100～300 m in Zigui and Lichuan counties and eastward to less than 40 m in Hanchuan and E’zhou counties where only one sequence could be confirmed.The unconformity,river rejuvenation surface and lithology and lithofacies transition surface are the main types of sequence boundaries.The sequence stratigraphic framewoks are constructed on the basis of sequence subdivision of four outcrop sections and one well log section,which indicate that the sedimentary fabric of TS3-TS4 is of higher energy than that of TS1-TS2.Under the background of tectonic,paleogeography and paleoclimate comprehensive controlling over the stacking patterns of sequences,the studied area experienced a conversion from the lacustrine-swamp system to the fluvial system,which displays the earlysedimentary characteristics of the northern mid-Yangtze foreland basin.

关 键 词：中扬子北缘 前陆盆地 晚三叠世 陆相层序地层 

分 类 号：TE121.34[石油与天然气工程—油气勘探]