LU Hui1, SUN Zai-bo2, ZHANG Hu2, ZHOU Kun2, YAN Xun2, ZENG Wen-tao2, YU Sai-ying2,WANG Xiao-feng2
(1. Yunnan Institute of Geological Environment Monitoring, Kunming 650216, China;
2. Yunnan Institute of Geological Survey, Kunming 650216, China)
Abstract: Based on 1: 250000 regional geological surveys, petrogeochemistry and diagenetic chronology of Menheng granite were studied in this paper. The results show that the contents of SiO2 and K2O+Na2O range from 72.73 wt% to 77.24 wt% and 4.28 wt% to 9.01 wt% (average 7.38 wt%), respectively. The ratios of K2O/Na2O range from 0.65 to 20.84 (mean 2.67). These results suggest that Manheng granite has features of high SiO2 and alkaline-rich. C.I.P.W standard mineral results show high q and c values. The standard mineral assemblage is c+q+or+ab+an+hy, belonging to the Al and Si supersaturation series. The A/NCK ratios are between 1.05 and 2.66 (mean 1.29), indicating that Manheng granite belongs to S-type granite. LA-ICP-MS zircon U-Pb dating of Manheng granite yields 446.1±2.5 Ma, suggesting that it had formed during the Late Ordovician. We consider that Manheng granite has characteristics of syn-collision magmatic active and is the product of periphery plate collision orogeny during the Late Pan-African and in the process of the convergence of Gondwana continent.
Keywords: granite; zircon U-Pb ages; syn-collision orogenic setting; Ximeng City
Email: ynddyszb@qq.com
ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 515-521
