闽浙古元古代斜长角闪岩的离子探针锆石U-Pb年代学

SHRIMP U-Pb ZIRCON GEOCHRONOLOGY FOR AMPHIBOLITE FROM THE PRECAMBRIAN BASEMENT IN SW ZHEJIANG AND NW FUJIAN PROVINCES

闽西北-浙西南的古元古代斜长角闪岩是目前华夏地块出露的最老岩石。对代表性样品进行了元素和离子探针锆石U-Pb年龄分析，其年龄为（1766±19）Ma。结合前人对该地区片麻状花岗岩的锆石U－Pb和Nd同位素的研究资料，认为浙西南-闽西北地区在1.77Ga前发生了广泛的板内玄武岩浆活动，华夏古陆很可能是在古元古代晚期由太古亩地壳再循环物质重熔结晶克拉通化而形成的。

Deochemical data and SHRJMP U-Pb zircon isotopic age of (1766±19)Ma are reported for the amphibolites exposed in NW Fujian-SW Zhejiang and genetally accepted as the oldest rocks in the Cathaysia Block. These data. combined with previous U-Pb zircon and Nd isotopic studies for the granitic gneisses in the region. provide new constraints on the crustal evolution of the Cathaysia Block. It is therefore concluded that the Cathaysia Block was most likely formed at 1.77 Ga through ctatonization by granite formation as the result of re-crystallization of crustal materials derived from an Archean provenance, which was probably triggered by the intraplate basaltic magmatism.