浙西北地区反转构造初步研究

通过浙西北地区金衢、乌马和杭嘉湖3个地震解译剖面及地表地质的综合分析,指出研究区在以T₂为主变形期的逆冲变形体制之前存在同方向的引张体制,并随后发生反转。通过计算反转比等综合分析,发现其总体反转程度自南东往北西方向逐渐变小,反映出反转后的褶皱冲断变形程度呈现自南东往北西方向变弱之趋势。

A PRELIMINARY STUDY OF THE INVERSION TECTONICS IN NW ZHEJIANG,SE CHINA

Inversion tectonics has been considered as one of the main characteristics of foreland fold and thrust belts. One important parameter to describe the inversion degree of inversion tectonics is the inversion ratio, which is determined by comparing the apparent length along the fault dipping direction before and after the inversion. The Jiangshan Quzhou, Majin Wuzhen and Hangzhou Jiaxing Huzhou cross section are selected to be discussed in Northwest Zhejiang foreland fold and thrust belt because they are distributed in the southwest, central and northwest cross sectional position, respectively. By calculating the inversion ratio and other synthetic analysing, we have found that an extensional realm that existed in the Palaeozoic period in Northwest Zhejiang had been transported into a compressional realm in the early Mesozoic time, and the degree of structural inversion decreases from southeast to northwest. Together with the spatial temporal distribution of the tectonic facies and structural styles in Northwest Zhejiang foreland fold and thrust belt, the authors conclude that the inversion tectonics is compatible to the tectonic vergence of Northwest Zhejiang foreland fold and thrust belt, and is probably due to a significant orogenesis which happened in Northwest Zhejiang in the early Mesozoic time.