山东胶南威海造山带荣成岩套花岗质片麻岩的形成时代——锆石SHRIMP U-Pb定年

The Forming Age of Granitic Gneiss in Rongcheng Rock Series in Jiaonan-Weihai Orogen Belt

摘要:

胶南-威海造山带荣成岩套花岗质片麻岩由闪长质片麻岩石英闪长质片麻岩英云闪长质片麻岩奥长花岗质片麻岩花岗闪长质片麻岩黑云二长花岗质片麻岩二长花岗质片麻岩类组成，早期为TTG质花岗岩，晚期为二长花岗岩类。自早到晚存在明显的富钾演化特征。根据新的SHRIMP UPb锆石定年结果，该岩套早期闪长质片麻岩年龄为(741±10)Ma，英云闪长质片麻岩年龄为780～760Ma。晚期二长花岗质片麻岩年龄为760~714Ma。所以，可把荣成岩套花岗岩时代限定在800~700Ma之间（南华纪），其形成与华北克拉通岩石圈减薄有关。

Abstract:

Granitic gneisses in Rongcheng rock series of JiaonanWeihai orogen belt is composed of dioritic gneissquartz dioritic gneisstonalitic gneiss trondhjemitic granitic gneissgranodioritic gneissbiotite monzonitic granitic gneissmonzonitic granite. It is TTG granitoids in early period, while is monzogranite in the late period. It has obvious evolution characteristics of potassiumrich from early to late period. According to new SHRIMP UPb zircon dating results, the age of dioritic gneiss in early period is (741±10)Ma, and the age of tonalite gneiss is 780~760Ma. The age of adamellite gneiss in late period is 760~714Ma. Therefore, the era of Rongcheng rock series is limited between 800~700Ma (Nanhua). Its formation has close relation with lithospheric thinning of the North China craton.