Browsing by Author "Gao, B."
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Item Early Mesozoic tectono-magmatic activity and mineralization in northeast China: Evidence from Re-Os to U-Pb studies of the Taipingchuan porphyry Cu-Mo deposit in the Derbugan metallogenic belt(International Geology Review, 2014-10) Zhang, L.; Gao, B.; Li, W.; Chen, Z.; Sakyi, P.A.; Jin, X.The Taipingchuan Cu-Mo deposit is a recently discovered large porphyry deposit located in the north of the Derbugan metallogenic belt of northeastern China. The geochronological data of the deposit yielded a Late Triassic zircon U-Pb age of 202 ± 6 Ma from a granodiorite porphyry that hosts the Cu-Mo mineralization. Measured Re-Os isotopes of seven disseminated molybdenite samples yielded an isochron age of 200 ± 5 Ma with mean square of weighted deviates of 2.7, while those of seven veinlet molybdenite samples also produced an isochron age of 200.1 ± 2.5 Ma and mean square of weighted deviates of 3.3. These isochron ages show that a Cu-Mo mineralization event occurred at ca. 200 Ma. Based on regional tectonic evolution, we propose that the Late Triassic Cu-Mo mineralization of the host porphyry in the Derbugan metallogenic belt was mainly associated with the subduction of the Mongol-Okhotsk Ocean slab under the Ergun block, contrary to previous suggestion that it was related to the subduction of the Mesozoic Palaeo-Pacific plate. © 2014 Taylor & Francis.Item LLHR-type chalcopyrite Re-Os geochronology and geochemistry of the Xiaotongchang Cu deposit in south Ailaoshan and its geological significances(Journal of Geochemical Exploration, 2019-03) Li, W.; Gao, B.; Zhang, L.; Jin, X.; Sakyi, P.A.The Xiaotongchang Cu deposit is located in the south Ailaoshan and at the contact between Yunnan province of China and Vietnam. Four Cu ore bodies are distributed parallel to each other in an interlayer fracture zone in the Permian Emeishan basalt. The major ore mineral in the deposit is chalcopyrite, and the main gangue minerals are quartz and calcite. New Re-Os data for chalcopyrite from the Xiaotongchang Cu deposit show tens of ppb Re abundances (1–86 ppb) and contain essentially no common Os. All the samples have extremely high 187Re/188Os (up to 2.3 × 104), and the dominance of radiogenic Os and high 187Re/188Os are diagnostic features of “LLHR” (low-level, highly radiogenic) sulfides. The Re-Os isochrone age for the No. 1 and No. 3 Cu bodies show that the phase of Cu mineralization predominantly occurred in the Middle Triassic, with an age of 230.6 ± 1.1 Ma. Thus, the mineralization occurred much later than the periods of major eruption of the Emeishan large igneous provinces, indicating a closer relationship with the late collisional processes in the Ailaoshan orogenic belt. Combined with REEs patterns and consistently positive δ34S values (7.4–9.2‰), it can be concluded that the ore-forming materials of the Cu deposit are derived from a mixture of mantle and crust components.