Finding and Significances of Chongjiang Porphyry Copper (Molybdenum, Aurum) Deposit, Tibet
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摘要: 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Abstract: 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.
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Key words:
- Chongjiang /
- large-scale porphyry copper deposit /
- new progress
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图 1 西藏自治区尼木县冲江铜矿区地质简图
1.第四系; 2.设兴组凝灰岩; 3.含巨斑二长花岗斑岩; 4.石英闪长玢岩; 5.铜矿体及编号; 6.断层及编号; 7.钾硅化; 8.黄铁绢英岩化; 9.泥化; 10.青盘岩化
Fig. 1. Geological sketch map of Chongjiang copper deposit, Tibet
图 2 含矿斑岩w (K2O) -w (SiO2), w (K2O) -w (Na2O) 和wNa2O)-w (K2O)图解以及稀土配分模式
Fig. 2. w (K2O) -w (SiO2), w (K2O) -w (Na2O) and wNa2O)-w (K2O) diagrams and REE distrbution patterns of mineralizing porphry
图 3 不同环境构造含矿斑岩w (Rb) -w (Y+Nb) 图解
VAG.火山弧花岗岩; ORG.洋脊花岗岩; WPG.板内花岗岩; COLG.同碰撞花岗岩
Fig. 3. w (Rb) -w (Y+Nb) diagram of mineralizing porphyry with different origins
表 1 西藏冲江斑岩铜矿床岩石化学成分
Table 1. Petrochernistry cornponents of wall rock and mineralizing porphyry in Chongjiang porphyry Cu deposit, Tibet
表 2 西藏冲江含矿斑岩的微量元素分析结
Table 2. REE and trace element components of wall rock and mineralzing porphyry in Chongjiang porphyry Cu deposit, Tibet
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