西藏冲江大型斑岩铜(钼金)矿床的发现及意义

冲江斑岩铜(金钼) 矿床是近年来在冈底斯造山带中寻找斑岩铜矿最先取得突破的一个大型矿床.矿化、蚀变具中心式、面型分布特点, 其中钾硅化带大体上与强铜矿化带相对应.根据ICPMS测试、辉钼矿Re-Os及SHRIMP锆石U-Pb测年结果, 含矿斑岩高钾富碱过铝, 强烈富集轻稀土(LREE/HREE为8.56~ 23.1), 无Eu异常(平均1.001), 具有微弱的负Ce异常(平均0.84), 微量元素显示Ⅰ型和A型花岗岩的过渡特征, 反映斑岩岩浆作用与拆沉作用及其伴生的软流圈物质上涌有关.矿床形成于中新世(1 4~ 1 6Ma) 陆内造山体制向伸展走滑体制转换的过渡时期 

Finding and Significances of Chongjiang Porphyry Copper (Molybdenum, Aurum) Deposit, Tibet

The Chongjiang copper deposit is a large porphyry copper (molybdenum, aurum) deposit found in Tibet in recent years. It is also the first one that has made great breakthrough during the process of looking for porphyry copper deposit in Gangdise orogenic belt. The deposit has the characters of circular and surfacing model in mineralization and alteration belt. Cu mineralization is according to K-Si alteration belt approximately.Methodssuch as ICPMS on the rocks with mineralization, Re-Os dating on molybdenite and U-Pb dating on zircon, were used in this research. The results show that the mineralizing porphyry enriches in K, Na, Al and light rare earth element (LREE) with high LREE/HREE (8.56-23.1). The porphyry is normal in Eu (δEu=1.001), but weak negative abnormal in Ce (δCe=0.84), and shows the characteristics of the transitional granite between type Ⅰ and type A. The characteristics reflect the magmatism related to asthenospheric upwelling. The Chongjiang porphyry copper (molybdenum, aurum) deposit formed in 14-16 Ma, the transitional period of extrusion and extension in orogenic belt.