湘赣桂地区加里东期构造变形特征及成因分析

Caledonian Structural Characteristics and Mechanism in Hunan-Jiangxi-Guangxi Provinces

系统解剖了华南早古生代地层出露较好且加里东运动比较典型的地区,包括广西的元宝山、越城岭、大明山、大瑶山、云开大山地区以及湘赣边境等地区。通过对其褶皱、断裂形态的描述与分析发现大明山、大瑶山地区EW向的寒武系褶皱是云开地块在晚寒武世-早奥陶世由南向北推覆挤压的结果,而桂北元宝山、越城岭地区及湘赣边境地区NE-NNE向的早古生代地层的褶皱是由于华夏地块与扬子地块在晚奥陶世-早志留世沿郴州-临武断裂收缩挤压的结果,而且这一收缩挤压是属于陆内造山事件而不是前人所说的洋陆俯冲事件和陆-陆碰撞造山事件,且加里东运动先由南向北、后由东向西逐渐拓展,变形强度由强到弱。

This paper selects some regions with many typical Lower Paleozoic strata and intensive Caledonian orogeny. The regions mainly include the Yuanbaoshan-Yuechengling,Damingshan-Dayaoshan,Yunkai mountains areas in Guangxi Province,as well as the Hunan-Jiangxi border area. By the description and analysis of the folds and fractures in these regions,it shows that the E-W-striking Cambrian fold belts in the Damingshan-Dayaoshan area were caused by the Late Cambrian-Early Ordovician nappe thrusting and pushing of the Yunkai Block from south to north. However,the NE-NNE-striking fold belts of Lower Paleozoic strata in the Yuanbaoshan-Yuechengling area and Hunan-Jiangxi border area were caused by the Late Ordovician-Early Silurian collision between the Cathaysian Block to the Yangtze Block along the Chenzhou-Lingwu fault zone. Moreover,this shortening was neither related to ocean-subduction nor continent-continent collisional event,but the intracontinental orogenesis. The Caledonian Movement was gradually propagated from south to north at early stage and from east to west at late stage,and the deformation strength increased from south to north.