鲁西2.5~2.7Ga构造岩浆热事件:泰山黄前水库TTG侵入岩的野外地质和锆石SHRIMP定年

鲁西是华北克拉通太古宙基底典型分布区之一,存在新太古代早期到晚期长期连续的地质演化的记录。在泰山地区黄前水库北侧,我们对相互关系十分清楚的不同类型和时代TTG岩浆岩进行了详细野外地质观察和锆石SHRIMP U-Pb定年。早期片麻状英云闪长岩为望府山杂岩的一部分,具有深熔特征,岩浆锆石和变质锆石年龄分别为2695±7 Ma和2630±10 Ma。早期片麻状英云闪长岩被奥长花岗岩脉切割,后者的两组锆石年龄分别为2626±8 Ma和2689±12 Ma,分别代表了其形成时代和捕获锆石年龄。之后,它们又被晚期弱片麻状英云闪长岩(线峪岩体)侵入,其岩浆锆石年龄为2547±7 Ma,存在2.6~2.7 Ga捕获锆石。这些不同时代岩浆岩的形成过程是鲁西地区新太古代地质演化的一个缩影。

2.5~2.7 Ga Tectono thermal Events in Western Shandong:Geology and Zircon SHRIMP Dating of TTG Rocks in Huangqian Reservoir, Taishan Mountain

Western Shandong is an important exposure of Archean basement in the North China Craton, with a long term continuous geological record from early Neoarchean to late Neoarchean. We conducted detailed field observation and zircon SHRIMP U Pb dating on magmatic rocks of different types and ages, which show clear contact relationships. The early gneissic tonalite, which belongs to the Wangfushan Complex, shows an anatexis feature and has magmatic and metamorphic zircons of 2695±7Ma and 2630±10Ma, respectively. It was cut by trondhjemite veins, which have magmatic and xenocrystal zircons of 2626±8Ma and 2689±12Ma, respectively. Both of them were intruded by late tonalite (Xianyu intrusive body) of 2547±7Ma, with 2.6~2.7Ga xenocrystal zircons. The formation of the magmatic rocks of different ages is considered to be a miniature of Neoarchean geological evolution in western Shandong.