内蒙古查干凹陷的构造格架与演化

查干凹陷发育于华北板块西北缘的古造山带基础之上，属造山期后的伸展垮塌型盆地。位于该凹陷东南部的“毛敦侵入体”和“毛东断层”主要形成于前白垩纪，均为盆地基底的查干础鲁深大断裂带的重要组成部分；前人所划分的“罕塔庙次凹”主体可能为前白垩系残留地层，而并非早白垩世断陷沉积。凹陷的构造格架受不同级次的断层带控制；主要构造样式可分为伸展构造、挤压构造、反转构造和具有走滑分量的构造4大类，并以伸展构造为主体。该区白垩纪-新生代的构造演化经历了伸展断陷发生、发展、弱伸展断-坳转化、稳定坳陷和挤压改造5个阶段。

Structural Framework and Evolution of Chagan Sag in Inner Mongolia

The Chagan sag developed on the ancient orogenic belts near the northwestern margin of North China Plate,which was a post-orogenic extensional collapse basin.Both of the "Maodun Intrusion" and "Maodong Fault" in the southeastern Chagan sag primarily formed before the Cretaceous period,and belong to the component parts of the Chaganchulu deep fault zone beneath Chagan sag.The "Hantamiao sub-sag" that was once considered to be a structural unit of Chagan sag,mainly consists of remnant pre-Cretaceous strata,but Early Cretaceous strata developed in the faulted basin.The structural framework was controlled by fault zones with variant scales in this sag.Generally,the structural styles can be divided into four primary patterns including extensional structures which were dominant,compressional structures,inversion structures,and the structures with strike-slip component.During the Cretaceous to Cenozoic era,the tectonic evolution of Chagan sag had underwent five stages,namely extensional faulted basin generation,development,weakly extensional faulted-depressed transition,steady depression,and compressional reform stages.