粤西福湖岭混合岩及其原岩的地质年代学研究

Geochronology of Fuhuling migmatite and its protolith in western Guangdong

为了深入认识华夏地块早古生代陆内造山作用相应的地壳再造过程,本文选取粤西福湖岭混合岩进行了详细的岩相学以及锆石U-Pb年代学研究。根据混合岩化程度,粤西福湖岭混合岩剖面由上而下可以分为3部分:混合岩化沉积变质岩、条带状混合岩和混合花岗岩。根据岩性与岩相学特征,福湖岭混合岩又可分为古成体、暗色体和浅色体。LA-ICP-MS锆石U-Pb定年结果及与区域上基底变质岩资料的对比研究表明,福湖岭混合岩的原岩(古成体)是形成于新元古代的变质沉积岩。粤西福湖岭混合岩的形成时代为441~435 Ma,是华夏地块早古生代陆内造山事件的重要产物。

In order to further understand the crust reworking process related to the early Paleozoic intracontinen- tal orogeny in the Cathaysia Block, this paper presents detailed studies of lithology, petrography and zircon U- Pb dating of the Fuhuling migmatites in western Guangdong Province. With the increasing migmatization, these rocks can be divided into three rock types： migrnatized para-metamorphic rock, stromatic migmatite and migmatitic granite （diatexite）. According to lithological and petrographic characteristics, the Fuhuling migraatites can be divided into three suites： paleosomes, melanosomes, and leucosomes. LA-ICP-MS zircon U- Pb dating results together with a comparison with the data of metamorphic basements from this region suggest that the protolith （paleosome） was meta-sedimentary rocks deposited in the Neoproterozoic, and the migmatiza- tion occurred at 441-435 Ma, related to the early Paleozoic intracontinental orogeny in South China.