Geochronology and Ore-Forming Geological Background of ～90 Ma Porphyry Copper Deposit in the Lhasa Terrane, Tibet Plateau
详细信息
- 责任者：Wang Baodi (Chengdu Institute of Geology and Mineral Resources ; Chengdu 610081 ; China) ; Xu Jifeng
- 刊名：Acta Geologica Sinica
- 出版年：2012
- 卷期：87(1)
- 关键词：斑岩铜矿床 ; porphyry copper deposit ; 斑岩钼矿床 ; porphyry molybdenum deposit ; 金矿 ; gold ores ; 西藏 ; Tibet
- 页码：p.71-80
- 图表：illus., 2 tables, 68 refs.
- 分类号：1001
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
mary name="EnDivSummary">A number of large-very large porphyry Cu-Mo-Au deposits have been discovered in the Tibetan plateau,which has caused widespread concern in recent years.Existing research results show that the formation ages of thse ore-bearing porphyries and porphyry deposits in the Tibetan Pleteau concentrate mainly on four stages:120~110 Ma,~90 Ma,54~45 Ma and 18~12 Ma,but the ore-forming geological background of porphyry deposits forming at the second stage(90Ma) is still controversial.This study reports the zircon LA-ICPMS U-Pb and molybdenites Re-Os ages of the porphyry Cu-Mo-Au deposits in the northern Lhasa terrane,along with analysis of ore-forming background.Two weighted average 206Pb/238U ages for two granodioritic porphyry samples are 92.1±1.2 Ma and 93.8±1.2 Ma,which probably record the age of magma crystallization,while the molybdenites Re-Os isotopic age of 88.2~89.6 Ma probably represents the age of mineralization of the Balazha porphyry deposits.Based on the regional geochemical data,this study suggests that the magmatism and mineralizaion at ~90 Ma in the northern Lhasa terrane was neither the prodcut of subduction of the Neo-Tethys ocean and oceanic ridge,which are represented by the Yarlung-zangbo suture,nor the direct result of subduction of the Bangongco-Nujiang Ocean,but likely the product of collision process after the subduction and closure of the Bangongco-Nujiang Ocean.
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