皖浙赣相邻区中生代以来构造活动及古应力场特征

The tectonic movements and the paleo-tectonic stress field features after Mesozoic period in the joint area among southern Anhui,Zhejiang and Jiangxi

皖浙赣相邻区位于中国东南大陆边缘,中生代以来经历多期强烈构造作用,是研究中生代以来构造运动的理想区域。本文以皖浙赣相邻区中生代以来的脆性断层为研究对象,通过系统的野外构造观测和运动学研究,在区内划分出了4期主要断裂构造,确定了各期断裂的运动学特征,恢复了古构造应力场。第一期构造大致发生于早侏罗世—中侏罗世末,应力场为近南北向挤压,可能与华南板块与华北板块碰撞最后阶段的挤压作用相关;第二期构造出现在早白垩世,应力场为近北东—南西向挤压,可能与太平洋板块向南—南西俯冲有关;第三期构造大致发生在晚白垩世末,应力场为北西—南东向挤压,与太平洋板块向欧亚大陆的北西向正向俯冲有关;第四期构造应力场为东西向挤压,可能与太平洋板块弧后扩张产生的向西侧向挤压及印度板块俯冲碰撞产生的向东挤出共同作用有关。

The joint area among southern Anhui, Zhejiang and Jiangxi is adjacent to east-southern continental margin between China plate and Pacific plate, where several periods of tectonic movements have taken place after Mesozoic period. Therefore, it is the ideal region for study on the tectonic movements. On the systematic structure analyses in field, four periods of tectonic movements have been certified,and the paleo-tectonic stress state has been reconstructed. The first tectonic movement is behave as S-N direction compression,was probably taken place from Early Jurassic to end of Middle Jurassic, and is possibly associated with the last collision between the North China block and the South China block. The paleo-tectonic stress state of the second period is characterized by NE-SW direction compression,is related to the S-SW ward subduction of Pacific plate during Early Cretaceous. The paleo-tectonic stress states of the third period is behave as NW-SW direction compression, is possibly associated with the north- westward suhduction of Pacific plate at the Late Cretaceous. The paleo-tectonic stress states of the fourth period is behave as E-W direction compression, is probably associated with the W-NW ward compression derived from the back-arc extension of Pacific plate and the eastward extrusion derived from the collision between India plate and Euro-Asian plate.