巴彦浩特盆地西部坳陷带构造演化史分析

The Study on Tectonic Evolution History of Western Depression Belt in Bayanhot Basin

本文研究了巴彦浩特盆地西部坳陷带的构造沉降史、构造拉张史，探讨了坳陷构造演化阶段。研究表明，西部坳陷带主要为一伸展型沉降带，形成于晚体罗世一第四纪，受北西一南京向的伸展作用控制。晚侏罗世一早白垩世为断陷活动期，新生代为刺陷活动期。晚侏罗世断陷活动较强烈，其拉张量和总沉降量均最大，分别达3800m和1613m，各时期的拉张量和沉降幅度沿坳陷走向自北而南均呈递减趋势。所有这些特征与巴彦乌拉山断裂的活动密切相关。西部坳陷带经历了结晶基底形成、强烈隆升、断陷、坳陷等4个构造演化阶段。

This paper had made a quantitative study on tectonic subsidence history and tectonic extensional history of the western depression belt in Bayanhot Basin,and discussed its stages of tectonic evolution. The study shows the western depression belt is a extensional subsidence belt controlled by extension along NW-SE direction during Late Jurassic-quaternary. Late Jurassic-Early Cretaceous is a faulting period. Cenozoic is a sag period. The extensional mount and total subsidence mount during each period gradually decline from the northern section to the southern section. Faulting activity during Late Jurassic is most intense. During this period,The extensional mount and total subsidence mount are biggest. All of above characters are related to the activity of Bayanwula mountain fault. The western depression belt underwent four tectonic evolution stages:the stage of formation of crystalline basement,the stage of intensely uplift, the stage of faulting activity,the stage of sag activity.