东秦岭-大别造山带南缘印支期以来构造层序耦合特征分析

Sedimentological responses of the coupling between tectonics and sequence since Indo-Chinese epoch in the southern margin of the eastern Qinling and Dabie orogenic belt,China

通过对东秦岭-大别山造山带南缘鄂东地区、荆当盆地、秭归盆地和川东北地区三叠纪-古近纪的构造层序对比研究,划分出三个大的构造层序,并分析了中上扬子地区印支期以来沉积盆地性质转换和迁移过程与构造层序的耦合关系,揭示了东秦岭-大别造山与成盆作用过程。认为早三叠世至中三叠世构造层序Ⅰ记录了扬子地台由克拉通盆地逐渐萎缩的过程,反映了印支期华北板块与扬子板块之间软碰撞未造山的过程;晚三叠世至早白垩世构造层序Ⅱ记录了前陆盆地的三次幕式演化过程,反映了早燕山期华北板块与扬子板块之间呈斜向、剪刀式由东向西陆-陆碰撞关闭以及前展逆冲叠置造山作用过程,与江南逆冲带联合作用形成前陆盆地沉降和沉积中心向西的迁移。晚白垩世至古近纪区域构造背景发生重大变化,构造层序Ⅲ记录了晚燕山期地壳快速均衡隆升,伸展断陷盆地形成演化过程。

Through comparing the tectonic sequences stratum of Triassic-Paleogene period in the east of Hubei, in Jingmen-Dangyang basin, in Zigui basin and in the northeast of Sichuan, on the southern margin of the eastern Qinling and Dabie orogenic belt, three main tectonic sequences are divided. This paper analyzes the coupled relationship between the characterized transition and transfer processes of depositional basins and orogenic belts of its surrounding area since Indo-Chinese epoch in the midupper Yangtze area. Through studying the stratigraphic framework of tectonic sequence, the characteristics of deposits and multi episode tectonic movements show the eastern Qinling and Dabie orogenic movement and basin formation processes.