甘蒙北山中南带新发现燕山早期走滑挤压推覆构造带

近年来在区域调查基础上,于甘蒙北山中南带首次发现了六条由南向北推覆的构造带,在每个推覆陶造带边缘发育大小不一的飞来峰。推覆体走向近东西,推覆在震旦系至中、下侏罗统之上,最大直观推覆距达55km,累积推覆距大于150km,并被上侏罗统不整合覆盖,形成时代为燕山早期。

A NEW DISCOVERY OF EARLY YANSHANIAN STRIKE-SLIP COMPRESSIONAL NAPPE ZONES ON MIDDLE-SOUTHERN SEGMENT OF BEISHAN MTS, GANSU

Six strike-slip compressional nappe zones which thrust from south to north are newly found in Caledonian-Variscan orogenic belt at middle-southern segment of Beishan Mts. They are distributed from north to south as Follows: 1. Huangshan-Hengluanshan-Yingzuihongshan nappe zone. 2. Pochengshan-Wulannuru-Sandaomingshui-Wengeshan nappe zone. 3. Yushishan-Hongshan-Dahuoluoshan-Shuangzhaozi-Jianquanzi nappe zone. 4. Baishan-Mingshujing-Liuyuan-Hongshanhu-Jijitaizi-Dingxin nappe zone. 5. Baidunzi-Leidongzi-Jinmiaogou-Yujing zi nappe zone. 6. Xijianquanzi-Hongqsishan-South Dingxin nappe zone. The 6 nappe zones extend in a sublautudinal arc convex to north and a group of klippens of different size is diveloped on its margin. The allochthonous sheets of the first three nappe zones consist of middle and upper Prorerozoic dolomite-marble and thrust on Sinian to Middle and Lower Jurassic deposits. The detachment planes of the rest three nappe zones occur between Carboniferous and Lower Permian deposits, or within middle Proterozoic metamorphic rocks and between the metamorphic rocks and Upper Paleozoic and Mesozoic deposits. The six nappe zones thrust north wards with an cumulative displacement 150 kin, and took blace in early Yanshanian. It is suggested that their formation enechanism might be related wtih the northward lateral conpressive stress generated by the slip along Ahum lift-lateral strike-slip fault.