黔东桂北加里东期两类构造变形特征与成因机制探讨

早古生代加里东运动造成华南强烈的构造变形，此次构造运动在黔东桂北地区主要表现为都匀运动和广西运动两幕。综合构造变形与沉积环境的研究认为，都匀运动作为局部的构造运动在凯里-三都断裂以西的黔中南地区影响明显；广西运动源于扬子地块和华夏地块沿江山-绍兴断裂带陆内挤压作用，形成自南东向北西的挤压应力的远程效应，向NW影响的范围止于凯里-三都断裂带。两幕构造运动在时空格局联合影响下形成了以断裂为界的两类构造特征：断裂以西主要受都匀运动的影响，发育EW向平缓褶皱、正断层等构造；断裂以东主要受广西运动的影响，发育NE向的褶皱、剪切带等构造。采自高武地区NE向韧性剪切带中的样品，其白云母⁴⁰Ar/³⁹Ar测年坪年龄为(416.4±1.8) Ma，等时线年龄为(417.7±1.8) Ma；采自黎平地区NE向劈理带中的样品，其绢云母⁴⁰Ar/³⁹Ar测年坪年龄为(426.5±2.3) Ma，等时线年龄为(437±10) Ma，这些变形年龄代表了广西构造运动发生的时限。

Characteristics and Genesis of Two Types of Tectonic Deformation During Caledonian in Eastern Guizhou and Northern Guangxi

Taking place in Eopaleozoic, Caledonian movement caused strong deformation in southern China and was mainly represented by episodic movements of Duyun and Guangxi. Comprehensive research on tectonic deformation and sedimentary environment holds that Duyun movement, as a local one, evidently influenced the middle and southern parts of Guizhou, the western area of Kaili-Sandu fault. Whereas, Guangxi movement originated from the squeezing of the Yangtze block and the Cathaysian block along the Jiangshan-Shaoxing fault. Under the influence of time and space, together the two movement events have formed two types of tectonic characteristics bordered by fault fracture. To the west of the fault fracture, this area is mainly influenced by Duyun movement and structures like EW folds and normal faults are developed. To the east, Guangxi movement shows its power, and structures such as NE folds and shear zones can be seen. The time of the occurrence of Guangxi movement is determined by samples collected from the study area. Among which samples from the ductile shear zone in Gaowu show that the plateau age of ⁴⁰Ar/³⁹Ar of muscovite is (416.4±1.8) Ma, and isochron dating is (417.7±1.8) Ma; those from NE cleavage belt in Liping show that the plateau age of ⁴⁰Ar/³⁹Ar of sericite is (426.5±2.3) Ma, and isochron age is (437±10) Ma.