江南古岛弧浙赣段基底地壳演化

双溪坞群、双桥山群等为江南古岛弧浙赣段的前寒武纪基底地层。依据基底地层建造的差异及蛇绿岩套和碰撞花岗岩等的分布,可将浙赣段江南古岛弧沿赣东北断裂划分为怀玉地体和九岭地体。怀玉地体基底地层建造以火山岩占主导,10—13亿年是该地体的重要成壳时期。九岭地体基底地层建造以浊流复理石占主导,14—16亿年为该地体的重要成壳时期。距今9亿年左右两地体相互碰撞拼接,与此同时,华夏古陆向江南古岛弧碰撞,至～8亿年、完成碰撞对接,开始震旦系盖层沉积。

CRUSTAL BASEMENT EVOLUTION OF THE ZHEJIANG - JIANGXI PORTION OF THE JIANGNAN PROTEROZOIC ISLAND ARC ZONE

The Shuangxiwu Group and Shuangqiaoshan Group represent Precambrian basement strata of the Zhejiang-Jiangxi section of the Jiangnan Proterozoic Island Arc Zone. The Zhejiang-Jiangxi section of the Proterozoic Island Arc Zone can be classified based upon the differences in the rock formation of the basement strata and the distribution of ophiolites and collision granitoids along the Northeastern Jiangxi Fault belt. The two terranes are the Huaiyu tertrane and the Jiulin terrane. The Huaiyu terrane volcanic rocks predonmiate in the basement strata of 1. 0—1.3 Ga as the most important period for crustal formation whereas basement strata of the Jiulin terrane are characterized by turbidity flysch sediments as the terrare underwent crustal accretion during 1. 4—1.6 Ga. About 0. 6 Ga ago, the Jiulin and Huaiyu terranes collied with each other. Cathysia subsequently came into collision with the Jiangnan Proterozoic Island are Zone. Collisions terminated at about 0. 8 Ga with the subsequent deposition of Sinian cover.