华南地块西南缘格林威尔期区域构造解析

STRUCTURAL ANALYSIS ON GRENVILLE-AGED DEFORMATION IN THE SOUTHWEST MARGIN OF THE SOUTH CHINA BLOCK

从构造变形的角度入手,通过观察华南地块西南缘前震旦纪各岩石单元野外露头上的变形特征,运用构造解析方法,识别出不同期次变形构造的形态和位态特征及其在空间上的组合关系,划分变形构造的世代,结合近年来年代学研究成果,确定不同期次变形构造形成时代。研究表明,在华南地块西缘基底岩石单元中,发育格林威尔期的变形构造,其构造形迹东西向展布,该期构造变形的强度,在康滇地区各岩石单元中具有不均匀性,在野外露头上见到的格林威尔期小型紧闭、倒转褶皱主要分布在攀枝花周边的基底岩石单元中,而其南部的滇中地区,同期的褶皱构造相对较弱。根据格林威尔期构造位态特征,推断形成该期变形构造的构造运动方向为南北向的挤压运动。

Based on the field research and lab analysis on the deformations of the Precambrian in the southwest margin of the South China Block, three aged deformations are identified through structural analysis. The early intense small folds are found only in the Mesoproterozoic blocks while the late ones are found both in the Mesoproterozoic blocks and the upper ones. The age of the early folds indicates that Grenville-aged Orogeny occurs in the southwest margin of the South China Block. The direction of the Grenville-aged orogenic penetrative deformation structures in the southwest margin of the Yangtze Block is WE, and the intensity of the deformation is not at the same level along the southwest margin. The Grenville-aged orogenic penetrative deformation structures is stronger and more comprehensive in Panzihua area than those in the middle Yunnan province, and this is not consistent with the suturing position of the Grenville-aged Orogeny that is widely accepted at present.