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

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-一奥长花岗质片麻岩-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SHRIMPU-Pb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。

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

Granitic gneisses in Rongcheng rock series of Jiaonan-Weihai orogen belt is composed of dioritic gneiss-quartz dioritic gneiss-tonalitic gneiss-trondhjemitic granitic gneiss-granodioritic gneiss-biotite monzonitic granitic gneiss-monzonitic granite.It is TTG granitoids in early period,while is monzogranite in the late period.It has obvious evolution characteristics of potassium-rich from early to late period.According to new SHRIMP U-Pb 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.