丰城三溪峡——东乡石马岭推覆构造是扬子板块与华南板块的直接分界线

扬子板块与华南板以丰城三溪峡－东乡石马岭推覆构造分野。该推覆构造发育在萍乡－广丰深断裂与遂川－德兴深断裂的复合部位，具有可行－逆冲推覆性质。原地系统为扬子地层分区中元古界牛头岭组、高桥组和将军岭组，外来系统是华南地层分区新元古界源里组，分别相当于蓟县系修水组和青白口系上施组同期沉积。根据推覆变形形式、构造岩特征和变形程度，可将推覆体划分为包括糜棱岩亚带、糜棱岩化亚带在内的变形主带和劈理化带。韧性剪切变形与推覆变形同期产生，但影响范围更广泛。

SANXIXIA, FENGCHENG-SHIMALING, DONGXIANG NAPPE STRUCTURE:DIRECT DIVIDING LINEBETWEEN YANGZI PLATE AND SOUTH CHINA PLATE

The Yangxi Plate and the South China Plate is divided by the Sanxixia-Shimaling nappe struc-ture,which occurs in the compounding position of the Pingxiang-Guangfeng deep fault and the Suichuan-Dexing deep fault,displaying a dextral obduction character.The autochthone consists of the Mid-Proterozoic Niutouling Formation,Gaoqiao Formation and Jiangjunling Formation of the Yangzi Stratigraphic Region,while the al-lochthone is composed of the Neoproterozoic Yuanli Formation.In deposition age,the former corresponds to the Xiushui Formation of Jixian System while the latter,the Shangshi Formation of Qingbaikou System.Based on nappe deformation type,characteristics of tectonite,and degree of deformation,the nappe is divisible into the main deformation zone and the cleavage zone;the former consists of a mylonite subzone and a mylonitized sub-zone.The ductile shearing deformation took place contemporaneously with,but have a wider extent of influence than,the nappe deformation.