鄂西构造单元划分新方案

A new scheme of structural unit division in western Hubei

为了研究鄂西地区深层地质结构及其对油气成藏的控制作用,本文以断层相关褶皱理论为基础,采取浅表大剖面和地震剖面解析相结合的手段,对研究区的构造单元进行了重新厘定。经过一系列研究之后,制定出了新的构造单元划分方案,并得出了相应结论:1)基于寒武系底界的构造T0图,对鄂西地区构造单元进行了重新厘定;新划分的构造单元自北西到南东可分为利川构造带、恩施构造带、宣恩构造带、南北镇构造带、桑植—石门构造带和雪峰逆冲掩伏带;2)鄂西地区具备北西、南东分带性和垂向分层性。研究区的共性大于个性,整体的变形受基底滑脱层的形态变化的影响,呈现出多排背斜并排发育的现象。每一个新的构造单元以背斜为主体,其隆升基本上都受控于基底发育的基底逆冲断层,少数受控于基底双向逆冲构造。

In order to study the deep geological structure and its controlling effect on hydrocarbon accumulation in western Hubei area,based on the theory of fault related fold,we adopt the method of combination of superficial large section analysis and seismic section analysis to redefine the structural units in the study area.After a series of studies,we have worked out a new structural unit division scheme,and obtained the corresponding conclusions:1)Based on the structural T0 map of the Cambrian bottom boundary,the structural units in the western Hubei area are redefined.The newly divided tectonic units can be divided into Lichuan structural belt,Enshi structural belt,Xuanen structural belt,Nanbeizhen structural belt,Sangzhi‐Shimen structural belt and Xuefeng thrust belt from northwest to southeast.2)The western Hubei area has the characteristics of horizontal zonation and vertical stratification.The general character of the study area is greater than the individual character.The deformation of the whole area is affected by the morphological changes of the basement detachment,showing the phenomenon of multiple anticlines developing side by side.Each new structural unit is dominated by anticline,and its uplift is basically controlled by basement thrust developed in basement,and a few by basement bidirectional thrust.