内蒙古阿拉善右旗恩格尔乌苏一带本巴图组构造变形分析

发布时间：2018-02-22 23:59

本文关键词： 本巴图组构造属性构造演化三期褶皱叠加　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：研究区位于中蒙边境附近,处于华北板块西北陆缘活动带上,经历了复杂的地质演化过程,受到不同构造单元和构造演化阶段的影响,大地构造位置十分重要,但由于研究区内自然环境恶劣,研究程度较低。本次研究的目的主要是通过对阿拉善盟恩格尔乌苏地区1:5万地质图进行初步分析,结合野外褶皱构造形态地质调查。对恩格尔乌苏一带本巴图组的构造属性,运动演化进行分析,从而建立起比较完整的构造演化框架并对区域大地构造意义进行有益的探讨。通过详细的野外地质调查,在前人的基础上新的发现和认识有:研究区中发育有三期褶皱相互叠加改造,枢纽主要呈SE、SW、近EW及近NS向展布。早期褶皱为一期同斜倒转褶皱,为地层原始层理的褶皱,由于后期褶皱的叠加作用,早期构造形迹发育的比较分散,反映了岩层初始阶段受到顺层剪切作用而形成。中期褶皱为本巴图组构造规模最大的一期,轴迹近EW向,为恩格尔乌苏断裂带碰撞造山作用产生的近NS向挤压力作用于恩格尔乌苏南部的本巴图组而形成的,由于晚期褶皱叠加改造,中期褶皱的轴迹发生波状弯曲。晚期褶皱的主应力方位发生改变,受近EW向挤压作用,形成宽缓褶皱。晚期褶皱构造的形成存在两个方面的可能。一方面原因是恩格尔乌苏断裂带碰撞造山作用之后会出现应力松弛,主应力发生变化,从而形成第三期近NS向宽缓褶皱。另一方面燕山期的中国大陆的板内变性特征为形成一系列NNE或NE向纵弯褶皱,且构造运动强度总体呈现东强西弱的特征。此外燕山期的褶皱轴向按时间顺序,从早到晚,构造线呈现为逆时针转动,本巴图组第三期褶皱的形成可能与其相关。
[Abstract]:The study area is located in the border near the North China plate in the northwest margin active belt, has experienced complex geological evolution process, affected by the different tectonic units and tectonic evolution stage, tectonic position is very important, but because of the natural environment in the study area is bad, the lower the degree of research. The aim of this study is to a preliminary analysis based on 1:5 000 geological maps Alashan Engel Wusu region, combined with field geological survey form folds. The tectonic attribute of Engel Wusu group Bartle, evolution analysis, so as to establish a relatively complete framework and tectonic evolution are explored on the regional tectonic significance. Through detailed geological survey and on the basis of previous discoveries and understanding: in the study area for a period of three superimposed fold development transformation, mainly in the hub SE, SW, near EW and near The NS trending folds. Early for a period of homoclinal overturned fold, for the formation of original bedding folds due to superposition. The late fold, scattered early structural development, reflects the initial stage of rock by bedding shearing formed. The mid fold for a period of the Bartle group structure of the largest axis near EW, near NS for Engel Wusu fracture belt collision orogeny to pressure on the Bartle group Engel Southern Wusu formed, due to the late superimposed fold, fold the middle axis bending. Late wavy folds of the principal stress orientation changed by near EW extrusion effect of the formation of broad folds. Folds formed in late may exist in two aspects. One reason is the Engel fault belt after collision orogeny Ursula will appear stress relaxation, stress change, thus forming Third close to NS fold. Chinese, changeable plate on the other hand Yanshan period in the formation of a series of NNE or NE fold to longitudinal bending, and the intensity of tectonic movement shows the characteristics of strong and weak in the West. In addition Yanshan fold axial period according to the time sequence, from morning to night, construct line showing rotation for the counterclockwise, forming the Bartle group third fold may be related.

【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P548

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