Duan Z.,Chengdu Geological Survey Center |
Li G.,Chengdu Geological Survey Center |
Wang B.,Chengdu Geological Survey Center |
Li Y.,Chengdu Geological Survey Center |
And 3 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2015
The newly discovered Chagele skarn-porphyry deposit is located in the Middle-Gangdese metallogenic belt. This study focuses on the zircon U-Pb age of the ore-bearing porphyry and molybdenite Re-Os, the whole rock major elements, trace elements, and the Sr-Nd-Hf isotopic data of the ore-bearing rocks in Chagele deposit. The zircon U-Pb age of the ore-bearing porphyry changes from 64.6 to 62.9 Ma, which represents the magmatic crystallization age. The Re-Os isotopic age shows that the deposit was formed at (62.3±1.4) Ma, which is consistent with the magmatic age in the study area. Combing with the extensive volcanic event of Linzizong Group, these new data suggests that the different scales of mineralization were formed at different stages in the entire collision between India and Eurasia continent. The ore-bearing porphyry of Chagele deposit has high contents of SiO2, K2O, Rb, Th, and U, coupled with low contents of TiO2, P2O5, negative anomalies of Nb, Zr, variable εHf(t) (-7.02~-1.27), and ancient TDM C (1093~1419 Ma). In comparison with the Gangdese continental crust composition, the ore-bearing porphyry is high in εNd(t) (-6.64~-5.79) and low in (87Sr/86Sr)i (0.711813~0.717307). These geochemical features indicate that the porphyry of Chagele deposit is similar to the peraluminous feature of S-type granite. The above discussion suggests that the Paleocene magmatism and mineralization in the middle section of the Middle-Gangdese metallogenic belt could be formed through partial melting of the ancient crust materials of Gangdese micro-continent accompanying with fractional crystallization, which was probably induced by upwelling of mantle-derived magma in the main collision between Indian and Eurasia continent. © 2015, Jilin University Press. All right reserved.
Liao Z.-W.,Post University |
Liao Z.-W.,Chengdu Geological Survey Center
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2010
Based on comparison of geological features of the copper and gold deposits related to Emeishan basalt, combining with isotopic geochronologies from individual deposit done by predecessors, the authors established a spatial-temporal framework and a metallogenic model for these deposits. It was shown that the Emeishan basalts erupted and upwelled because of mantle uplifting during Late Caledonian to Early Hercynian. They carried significant Cu and Au, which not only formed Cu-Au mineralization in basalts and tuffs, but also provided important source for post-volcanism stratabound Cu-Au deposits. Copper and gold leached by hydrothermal fluids in the volcanic protores would migrate along faults and fractures, which were driven by structural-thermal driven effects in Indosinian and Yanshanian. They would subsequently precipitate in favorable locations where were abrupt changes of structure and chemical potential. Cu and Au enriched in it, and finally ore bodies formed.