大巴山前陆西段叠加构造变形分析及其构造应力场特征  

An Analysis of Superposed Deformation and Tectonic Stress Fields of the Western Segment of Daba Mountains Foretland

作　　者：施炜[1] 董树文[2] 胡健民[1] 张忠义[1] 刘刚[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质科学院,北京100037

出　　处：《地质学报》2007年第10期1314-1327,共14页Acta Geologica Sinica

基　　金：中石化海相前瞻性科研项目<大巴山前陆构造演化;流体运移与油气远景>和<大巴山前陆叠加变形研究>资助的成果

摘　　要：大巴山前陆西段发育典型的横跨叠加褶皱,清楚地记录了自身构造演化历史,为查明大巴山前陆构造体制转换提供了非常有利的条件。本文通过野外褶皱形态分析,结合层面和断层面滑动矢量的观测,获得大巴山前陆西段中生代主要的两期挤压构造应力场,即早期(T3—J1)的构造应力场以近南北向挤压为主,大巴山地区受其控制,发生近东西向展布褶皱变形,这期构造变形与印支运动有关;晚期,即J3—K1期间,大巴山构造体制发生重大转变,本区构造应力场由近南北挤压转变为近东西向强烈挤压,大巴山发生强烈构造变形,大巴山推覆构造带以断裂活动为主,镇巴—城口—房县断裂带强烈向大巴山前陆逆掩。而大巴山前陆则以强烈的近南北向延伸的褶皱变形为主,早期近东西向褶皱遭受强烈改造,形成大巴山前陆西段较为典型的横跨叠加褶皱构造。这期构造变形是燕山运动早期活动的结果。大巴山叠加变形的研究不仅为研究中国盆—山系统变形特征提供了具体例证,而且对大巴山前陆油气勘探起重要指导作用。The typical superposed deformation developed in the western segment of Daba Mountains foreland, which records distinctly its history of tectonic evolution and is beneficial to research on tectonic regimes conversions. Based on analysis of folded forms croped out in the region, combined with observation of bedding plane and fault slip vector, in this paper, we study in detail on two main periods of Mesozioc tectonic compression stress fields, near SN-trending compression during T3-J1 and near EW-oriented compression during J3-K1. At earlier stage （T3-J1）, controlled by near SN-trending compression tectonic stress field, a series of near EW-trending folds formed at Daba Mountains, which may be caused by Indosinian movement. At later stage （J3--Kt）, the tectonic regime changed to near EW-oriented compression, therefore, earlier near EW-trending folds was deformed strongly, and a series of SN- oriented folds developed. Thus, superposed folds of Daba Mountains foreland formed. At the same time, Fangxian--Zhenba fault zone thrusted intensitily westward. The later deformation of Daba Mountains may resulted from Yanshanian Movement. To study on superposed deformation of Daba Mountains bears on importance for research on blocks interaction in this region, and takes an instructive action on oil and gas of the Northern Sichuan.

关 键 词：大巴山前陆 叠加变形 构造应力场 印支运动 

分 类 号：P542[天文地球—构造地质学]