鄂尔多斯西缘逆冲褶皱带构造特征及其南北差异的形成机制  

Tectonic Characteristics of the Western Ordos Thrust—Fold Belt and the Causes for Its North—South Segmentation

作　　者：张进[1] 马宗晋[1] 任文军 

机构地区：[1]北京大学地球与空间科学学院,100871 [2]东方物探公司长庆物探处,银川750006

出　　处：《地质学报》2004年第5期600-611,共12页Acta Geologica Sinica

基　　金：国家重点自然科学基金项目 (编号 4983 40 2 )资助的成果

摘　　要：研究表明鄂尔多斯西缘构造带经历了多次的逆冲推覆作用 ,广义上该构造带是一个大型的双冲构造系统 ,由下古生界和中生界两套变形组成。同时明确了狭义的鄂尔多斯西缘构造带南北两分的构造特征以及南北两部分的形成机制 ,南北两部分具有各自相对独立的形成机制与过程。北段主要包括桌子山段、贺兰山中、北部、银川地堑地区和横山堡段 ;南段主要包括贺兰山南部、马家滩段以及沙井子段。确认了在鄂尔多斯西缘构造带南北两部分之间存在着一个较大的侧断坡。它的存在导致了鄂尔多斯西缘构造带南北两部分之间的分化 ;该构造带在平面上的凹凸展布也反映了这种分化。而且在中生代狭义的鄂尔多斯西缘构造带南北两部分形成时间以及持续时间也不同。北段活动时间短 ,主要形成于晚侏罗世 ;而南段活动时间长 ,在晚三叠世就已经开始活动。Based on analysis, several thrustings that have occurred along the western margin of the Ordos Basin are shown. In broad sense, this thrust zone is a large duplex system consisting of the deformation of lower Paleozoic and Mesozoic strata. The tectonic characteristics of the north and south sub-zones of the zone (in narrow sense) and the causes for them are also discussed; the mechanism and processes for the shaping of two sub-zones are different. The northern one includes the Zhuozishan segment, the central and northern parts of the Helan Mountains, Yinchuan rift and Hengshanpu; the southern one includes the southern part of the Helan Mountains, the Majiatan and Shajinzi segments. One large lateral ramp between the northern and southern sub-zones is found. It is this lateral ramp that caused the differentiation between two sub-zones, and the arc-form showen in the map also implies that there is one lateral ramp between them. Furthermore, in the Mesozoic, the periods and the processes for them to take shape are different, too; the thrusting period of the north sub-zone that took shape in the Late Jurassic is shorter than that of the southern one that began forming in Late Triassic.

关 键 词：构造带 构造特征 鄂尔多斯 褶皱带 断坡 逆冲推覆 形成机制 贺兰山 晚三叠世 晚侏罗世 

分 类 号：P542[天文地球—构造地质学]