地质与勘探2017，Vol.53Issue(6)：1070-1089,20.
滇西分水岭矿区始新世岩浆岩成因及其构造指示:地球化学、锆石U-Pb年代学及Hf同位素制约
Petrogenesis and Tectonic Indication of the Eocene Porphyry in the Fenshuiling Mining Area, Western Yunnan Province:Constraints from Bulk Geochemistry,Zircon U-Pb Geochronology and Hf Isotopes
摘要
Abstract
The Fenshuiling mine is a large porphyry type copper-polymetallic deposit in Yongsheng County of Yunnan Province. The copper mineral-ization of this district is closely related to the porphyry, and orebodies mainly occur in the porphyry and outer hornfels zone. This work studied the bulk ge-ochemistry, zircon U-Pb dating and Hf isotopes of the porphyry from this mining area. The zircon U-Pb age of porphyry samples is 36. 0 ± 0. 2 Ma, in-dicating that the porphyry of this mine area is the product of the Eocene magmatic activity. Geochemical characters of the porphyry show large variation in SiO2(53.7% ~71.06%), high in K2O(1.67% ~6.1%) and Na2O+K2O( >8%), and the ratio of A/CNK is 0.35~1.03, and the porphyry be-longs to the K-rich calcined alkaline-alkaline and metaluminous-peraluminous alkalic series. Although the porphyry deposits are classified into alkali-rich intrusive rocks and A-type granite, microelements show that the porphyry is depleted in Ta, Nb, P, Ti and rich in Rb, K, La, Nd, revealing some C-adakite features. Thevalues ofεHf(t)from the zircon change from -8.70 to +4.67 and the values of tDM Cvary from 533Ma to 1062Ma,sug-gesting the Eocene porphyries were derived from the partial melting of the lower crust and associated with the addition of mantle source material. Combined with the regional geological evolution history, we suggest that the porphyry was formed in an extensional setting of the post-collision period. After the compression of continental collision, the stress relaxation led to the magma intrusion along faults and secondary faults,concomitantly forming copper poly-metallic deposits.关键词
始新世/斑岩/锆石U-Pb/Lu-Hf/分水岭/滇西Key words
Eocene/porphyry/zircon U-Pb/Lu-Hf/Fenshuiling/western Yunnan Province分类
天文与地球科学引用本文复制引用
周洁,王根厚,崔银亮..滇西分水岭矿区始新世岩浆岩成因及其构造指示:地球化学、锆石U-Pb年代学及Hf同位素制约[J].地质与勘探,2017,53(6):1070-1089,20.基金项目
云南有色地质局综合研究项目(编号:201307)资助. （编号:201307）
