鲁西地区新太古代中期岩浆活动——新甫山与上港等岩体锆石SHRIMP U-Pb定年的证据

Mid Neoarchean Magmatism in Western Shandong Province——Evidence of Zircon SHRIMP U-Pb Dating in Xinfushan and Shanggang Rock

新甫山、上港岩体分布于鲁西新太古代早期泰山岩群和英云闪长质片麻岩、条带状英云闪长质片麻岩组成的古陆核的东北部。主要岩性为片麻状花岗闪长岩及片麻状奥长花岗岩。根据新的锆石SHRIMP U-Pb定年结果,片麻状花岗闪长岩形成年龄为(2 613±12)Ma,片麻状奥长花岗岩形成年龄为(2 623±9)Ma,为新太古代中期形成。在泰山桃花峪—下港之间出露的条带状英云闪长质片麻岩中奥长花岗质脉体锆石U-Pb年龄在2 660～2 600Ma。该期岩体是新太古代早期英云闪长质片麻岩发生变质作用与重熔岩浆作用的产物。

Xinfushan and Shanggang rock distributed in early Archean Taishan group and northeastern part of the ancient continental nucleus which were composed of tonalitic gneiss and banded tonalite gneiss. Its main rock properties are gneissic granodiorite and gneissic trondhjemite. According to new zircon SHRIMP U - Pb dating, the forming age of gneissic granodiorite was （2613±12）Ma, and the forming age of gneissic trondhjemite was （2 623±9） Ma. They were formed in mid Neoarchean. Zircon U - Pb age of trondhje-mite veins in banded tonalite- diorite gneiss which were exposed between Taohuayu in Taishan mountain and Xiagang was 660-2600Ma. These rocks were the production of metamorphism and remelting magmatism in the new early Archean tonalitic gneiss.