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Ages and tectonic environment of the Bangong Co porphyry copper belt in western Tibet, China
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2006
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India-asia Collision ZoneEngineeringEast Asian StudiesCopper BeltPrecambrian GeologyTectonic EvolutionIndia-asia CollisionEarth ScienceBangong CoMesozoic TectonicsLanguage StudiesGeochronologyGreenstone BeltEast Asian LanguagesGeologyMineral DepositTectonicsStructural GeologyEconomic GeologyGeochemistryWestern TibetZircon Shrimp U-pbOre GenesisPetrologyTibetan Plateau
The ages, natures and tectonic environments of the Bangong Co porphyry copper belt have been preliminarily determined through a study of ore-bearing porphyries in the Dobuzha and Garqiong porphyry copper deposits in the porphyry copper belt. Zircon SHRIMP U-Pb dating yielded ages of 127.8±2.6 and 112.0±2.3 Ma for the two deposits respectively and indicates that the two deposits formed in a post-collisional stage of the orogen evolution (the Bangong Co-Nujiang ocean basin closed at 145 Ma). Geochemical analysis demonstrates that the ore-bearing porphyries of the copper belt belong to the shoshonite-high-K calc-alkaline rock series and are characterized by enrichment of large ion lithophile elements (LILE) such as Rb, K, Sr and Pb and depletion of high field strength elements (HFSE) such as Nb, Ta and Ti. These features are similar to those of the ore-bearing porphyries of the Gangdise porphyry copper belt. Differences between them lie in that the ore-bearing magma of the Bangong Co copper belt was generated at a shallower depth in a post-collisional crustal uplift stage, whereas the ore-bearing magma of the Gangdise porphyry copper belt in a stage of post-collisional crustal extensional collapse when the crust rose to the maximum height.