鲁西地区石门山—凤仙山岩体的锆石SHRIMP U-Pb定年及形成时代

Zircon SHRIMP U-Pb Dating and the Forming Age of Shimenshan-Fengxianshan Rock in Western Shandong

摘要:

鲁西地区石门山岩体主要岩性为片麻状花岗闪长岩，原划为新太古代早期侵入岩。根据新测锆石SHRIMP U-Pb年龄为（2530±8）Ma，其形成时代确定为新太古代晚期。凤仙山岩体为中粒二长花岗岩，锆石SHRIMP U-Pb年龄为（2513±12）Ma，并侵入片麻状花岗闪长岩。石门山岩体属峄山岩套，为TTG质花岗岩，是地幔岩浆侵入混入地壳物质形成的。凤仙山岩体属傲徕山岩套二长花岗岩，为上地壳物质重熔（深熔）作用形成的。峄山岩套TTG类岩石是2560～2530Ma壳幔岩浆活动的产物，岩体普遍具有片麻状构造，表明经历变质变形作用。未受区域变质作用的傲徕山岩套大规模壳源花岗岩是2530～2500Ma地壳物质部分熔融形成的，与华北克拉通新太古代末超大陆拼合有关，2530Ma是鲁西地区重要的构造热事件发生时期。

Abstract:

Lithology of Shimenshan rock in western Shandong is mainly gneissic granodiorite, which was originally classified into intrusive rocks in early period of Archean. According to newly measured zircon SHRIMP U-Pb age as 2530±8Ma, the formation age is determined to be the late period of Archean. Fengxianshan rock is monzogranite with medium size. Its zircon SHRIMP U-Pb age is 2513±12Ma, and intruded by gneissic granodiorite. Shimenshan rock belongs to Yishan rock set of TTG granitoids. It is formed by the intrusion of mantle mixed with crustal magma. Fengxianshan rock is monzogranite rock in Aolaishan rock set. It is formed by melting material at the upper crust (deep penetration) . TTG rocks in Yishan rock set with the age of 2560~2530Ma are the production of crust and mantle magmatism. Rock in general has a gneissic structure, which showed that it had experienced the metamorphism and deformation. Aolaishan rock set which has not experienced regional metamorphism were formed by partial melting of crustal material in 2530~2500Ma. It has colse relation with super continental fitting of craton in the late period of Neoarchean in Northern China. 2530Ma is an important tectonic thermal even in western Shandong.