Petrogenesis and Geochronology of the Ore-Bearing Porphyritic Rocks in Tangbula Porphyry Molybdenum-Copper Deposit in the Eastern Segment of the Gangdese Metallogenic Belt
详细信息
- 责任者：Wang Baodi (Chengdu Institute of Geology and Mineral Resources ; Chengdu 610081 ; China) ; Xu Jifeng
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(6)
- 关键词：斑岩铜矿床 ; porphyry copper deposit ; 斑岩钼矿床 ; porphyry molybdenum deposit ; 冈底斯山 ; Gangdise Range
- 页码：p.1820-1832
- 图表：10 illus., 3 tables, 53 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
This paper attempts to systematically study geochemical characteristics of Tangbula porphyritic rocks and Mo-Cu deposit, and determine the both ages by LA-ICPMS zircon U-Pb and molybdenites Re-Os isotopic dating. The results show that granitic porphyritic rocks and molybdenites were formed at 19.72±0.20 Ma, and 20.9±1.3 Ma, respectively. Within the error range, the both age are consistent with each other, indicating that the formation of porphyritic body and mineralization are at a same time. Geochemically, porphyritic rocks in Tangbula porphyry Mo-Cu deposit are similar to an adakitic rock. The authors suggest that ore-bearing porphyritic adakitic magmas were possibly produced by partial melting of the thickened mafic lower crust beneath the Gangdese block, which were heated by asthenosphere upwelling related to slab break-off in Miocene. In addition, the age range of the Gangdese metallogenic belt in post-collisional extension setting is from 21 to 12 Ma, mainly focusing on 17~13 Ma. Therefore, the main porphyritic mineralization probably lasted for about 4 Ma. Tangbula porphyry Mo-Cu deposit was one of the earliest porphyry deposits formed during post-collision stage in the Gangdese metallogenic belt.