• 责任者：Zhou Jinsheng (Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Meng Xiangjin
• 刊名：Acta Petrologica Sinica
• 出版年：2013
• 卷期：29(11)
• 关键词：斑岩铜矿床 ; porphyry copper deposit ; 金矿 ; gold ores ; 西藏 ; Tibet
• 页码：p.3755-3766
• 图表：9 illus., 3 tables, 46 refs.
• 分类号：1001
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

     The Qingcaoshan porphyry Cu-Au deposit, located in the southern Qiangtang Terrane, southern to northern Bangongco belt, is a newly discovered porphyry Cu-An deposit, having tremendous potential. Zircon U-Pb geochronology and trace element geochemistry of the ore-bearing granodiorite porphyry in the Qingcaoshan is studied first time in this article. Based on the LA-ICPMS U- Pb geochronological investigation of 13 zircon grains in ore-bearing porphyry, the weighted average of 206pb/208s U age of 114. 60 ±1.20Ma （ MSWD = 0. 33 ） was attained. The age is consistent with the age of ore-bearing porphyry in the Duobuza porphyry Cu deposit and the metallogenic age of the Bolong porphyry Cu deposit, which also located in this belt. Using zircon Ti thermometer, the forming temperature of zircons was calculated and most of them less than 700℃. Such a low crystallization temperature indicates that porphyry magma derived from rocks that experienced melting under near-water saturated conditions. The trace element geochemical investigation of zircons show that the Qingcaoshan porphyry Cu-Au deposit formed in continental arc, and that is consistent with the forming setting of the Duobuza porphyry Cu deposit from the predecessors＇ study. Similar diagenetic or metallogenic age and the same tectonic setting indicate that Bangongco porphyry copper belt exist objectively, which is mainly composed of the Qingcaoshan porphyry Cu-Au deposit, the Duobuza porphyry Cu deposit and the Bolong porphyry Cu deposit. Based on the geochemical characteristics of contemporaneous volcanic rocks in the Qingcaoshan and the Duobuza deposit and combined with the classical metallogenic model of porphyry copper deposits in arc settings, we proposed the geodynamic mechanism of Bangongco porphyry copper belt. In the early cretaceous, Bangongco oceanic crust is subducting northward. When subducted down to a proper depth, mass dehydration effect occurred in oceanic plate and it caused partial melting of mantle wedge. The magma enriched in Cu and other components, which produced by the partial melting migrate upward and develop into a magma chamber related to mineralization in shallow crust. Some of them erupt and form Meiriqiecuo Formation volcanic rocks. Particular part of them emplace in hypabyssal-uhra shallow crust and form porphyritic plutons or porphyry deposits. With the magma emplaced in the different time and place, finally Bangongco porphyry copper belt is formed.