地质通报2017，Vol.36Issue(2)：224-237,14.
桂东南大村和古龙岩体的成因:地球化学、锆石U-Pb年龄及Hf同位素制约
Petrogenesis of Dacun and Gulong plutons in south-east Guangxi:Constraints from geochemistry, zircon U-Pb ages and Hf isotope
摘要
Abstract
The Dacun and Gulong plutons were found in the southwest orogenic belt of the Yangtze block and the Cathaysia block, and the pluton has important geological significance in analyzing the regional tectonic evolution of South China. In this paper, two quartz diorite samples were collected from Dacun pluton and Gulong pluton for LA-ICP-MS zircon U-Pb dating, respectively, which yielded U-Pb ages of 438±1Ma and 435±2Ma, indicating that the Dacun pluton and Gulong pluton were both formed in Caledonian orogeny. The data show that the Dacun pluton and Gulong pluton belong to I-type granite which has calc-alkaline and aluminous-peraluminous features. The Hf isotopic compositions of zircons show that the rocks have εHf(t) values from 0 to +4, and TDM2(Hf) model ages are mainly concentrated in the range of 1.15~1.45Ga, implying that the magma was derived from the basic lower crust material, and the lower crust was formed in the Mesoproterozoic. According to geochemical features of the Dacun and Gulong plutons, Hf isotopic composition, and the dark particles-bearing pluton, in combination with regional geological conditions, the au-thors hold that, after the intracontinental collision orogenic period, the Dacun and Gulong plutons were formed along with the local lithosphere stretching-thinning, the upwelling of high temperature mantle materials from the asthenosphere, and the partial melting of the basic lower crust in the Mesoproterozoic. In the process of melting, there existed mixture of the upwelling mantle-derived magma formed in the source area at different levels, thus leading to the generation of parental magma. And then the magma experi-enced a certain degree of differentiation and evolution, finally forming rocks through solidification.关键词
加里东期/桂东南/大村岩体/古龙岩体/LA-ICP-MS锆石U-Pb定年/Hf同位素/地球化学Key words
Caledonian/southeast of Guangxi/Dacun pluton/Gulong pluton/LA-ICP-MS zircon U-Pb dating/Hf isotopic com-position/geochemistry分类
天文与地球科学引用本文复制引用
农军年,邹瑜,邱恩露,郭尚宇,叶栩松,向丰,文明,陆仕壹..桂东南大村和古龙岩体的成因:地球化学、锆石U-Pb年龄及Hf同位素制约[J].地质通报,2017,36(2):224-237,14.基金项目
中国地质调查局项目《桂东-粤西成矿带地质矿产调查》(编号:D20160035) （编号:D20160035）
