The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and relate...The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and related deposits are rarely reported, Our work identified a 〉200 km long felsic rock belt asso- ciated with Cu mineralization in the south Gangdese region. We report here zircon U-Pb ages, zircon Ce4＋/Ce3＋ values, and mineral assemblages of two Cu mineralized intrusions within the belt. A horn- blende granite and a diorite porphyry were emplaced at 177.3Ma and 166.3Ma, respectively. Geological occurrence and magmatic hematite-magnetite-chalcopyrite intergrowths suggest that Cu mineralization formed coeval with Jurassic intrusions. Mineralized intrusions have high zircon Ce4＋/ Ce3＋ and EuN/EuN ratios, and hematite-magnetite intergrowths, suggesting their parent magmas were highly oxidized, Hornblende is common and primary fluid inclusions are found in titanite and apatite, indicating their parent magmas were water-saturated and exsotved volatile phases at early stage of rnag- matic evolution. Those magma characters contribute to the formation of porphyry Cu deposits. Given that majority subduction-related porphyry Cu systems have been eroded following uplift and denudation, the well-preserved Early-Middle Jurassic cu mineralized igneous rocks in south Gangdese are favorable prospecting targets for subduction-related porphyry Cu deposits.展开更多
基金supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDB03010302)the DREAM project of MOST,China(2016YFC0600407)a contribution No.IS-2396 from GIGCAS
文摘The south Gangdese region is the site of subduction of the Neo-Tethys and subsequent continental col- lision. Compared with widespread Cretaceous and Cenozoic magmatism, Early-Middle Jurassic magmatic rocks and related deposits are rarely reported, Our work identified a 〉200 km long felsic rock belt asso- ciated with Cu mineralization in the south Gangdese region. We report here zircon U-Pb ages, zircon Ce4＋/Ce3＋ values, and mineral assemblages of two Cu mineralized intrusions within the belt. A horn- blende granite and a diorite porphyry were emplaced at 177.3Ma and 166.3Ma, respectively. Geological occurrence and magmatic hematite-magnetite-chalcopyrite intergrowths suggest that Cu mineralization formed coeval with Jurassic intrusions. Mineralized intrusions have high zircon Ce4＋/ Ce3＋ and EuN/EuN ratios, and hematite-magnetite intergrowths, suggesting their parent magmas were highly oxidized, Hornblende is common and primary fluid inclusions are found in titanite and apatite, indicating their parent magmas were water-saturated and exsotved volatile phases at early stage of rnag- matic evolution. Those magma characters contribute to the formation of porphyry Cu deposits. Given that majority subduction-related porphyry Cu systems have been eroded following uplift and denudation, the well-preserved Early-Middle Jurassic cu mineralized igneous rocks in south Gangdese are favorable prospecting targets for subduction-related porphyry Cu deposits.
