敦化市二合店一带(寒葱沟序列)碱性花岗岩形成构造环境及地质特征

The tectonic setting of the alkali granite of the Erhedian area (Hanconggou succession),Dunhua City and its geologic features

根据二合店一带碱性花岗岩的岩石化学成分和特征指数、微量元素及区域构造的综合分析 ,认为它属于大陆内部拉张构造环境中非造山期的A型花岗岩。其产出位置在敦—密断裂带附近 ,一些北西走向张性断裂为碱性花岗岩的侵入提供了有利的空间条件 ,并具有被动侵位的特点。从已测得UPb法等时线年龄 14 9 2± 9Ma、 16 6 5Ma、 14 6 9Ma 。

Arcorrding to comprehensive analysis on the chemical composition of the alkali granite,characteristic index,microelement and regional tectonics at the Erhedian,Dunhua area,Jilin province,it is considered as the nonorogenic 'A' type granite in the inner oceanic extension tectonic setting It is located near the Dun-mi faulted zone Some tension fractures with NW strike provide a favorable place for the intrusion of the alkali granite,having a character of the passive intrusion From the measured U-Pb isochron dating(149 2±9Ma,166 5Ma and 146 9 Ma),it is inferred that the upper limit of the intrusive period should be the end of late Jurassic period