内蒙古渣尔泰群层序地层及构造环境

SEQUENCE STRATIGRAPHY AND TECTONIC ENVIRONMENT OF THE CHARTAI GROUP, INNER MONGOLIA

中元古界渣尔泰群系由两个不整合面分隔的3个沉积序列所组成,即书记沟组一增隆昌组(Ds Ⅰ)、阿古鲁沟组(Ds Ⅱ)与刘鸿湾组(Ds Ⅲ)。它的基本环境模式是碳酸盐台地与台后盆地。碳酸盐台地向洋一侧的同沉积断裂与软沉积物中大规模的滑动,是重要的相带特征。新确立的增隆昌隆升(造陆运动)对渣尔泰群古地理格局具有重要意义。首次应用P.R.韦尔(Vail)所建立的层序地层学原则及模型与白云鄂博群进行地层对比。渣尔泰群属地台盖层,它是华北地台北部被动大陆边缘沉积。

The Middle Proterozoic Chartai Group consists of three depositional sequences, the Shujigou Formation- Zenglongchang Formation (DSⅠ), the Agulugou Formation (DSⅡ) and the Liuhongwan Formation (DSⅢ), which are separated and limited by two intenvening uncoformities. The carbonate plateform and back-plateform basin are the basic environmental model of the Chartai Group. The newly established Zenglongchang uplifting, an epeirogenetic uplift and subsidence movement, plays an important role in the formation of the paleogeographic framework of the Chartai Group and provides a criterion for correlation between the Chartai Group and the Bayan Obo Group. On the ocean ward side of the carbonate plateform, syndepositional faults and largescale slumping in the soft sediments are important marks of facies tract. Using the principle and model for sequence stratigraphy founded by P. R. Vail, the authors have explained and inferred the sedimentary facies and basin development of the Bayan Obo Group, and have made a high-resolution stratigraphical correlation between the Bayan Obo Group and the Chartai Group. This work is the first attempt of the kind in Inner Mongolia and has yielded good results. The Chartai Group, which was deposited on the northern passive continental margin of the North China Plateform, represents the plateform cover. The northern boundary of the North China Plateform should lie to the north of the Chartai Group. So far the recognizable geological records do not support the view that the boundary shifted to the south.