Large-scale Cenozoic alkali-rich magmatic rocks are exposed at the eastern margin of Tibet due to the interaction between the Indian and Eurasian plates.However,their petrogenesis and associated geodynamic processes r...Large-scale Cenozoic alkali-rich magmatic rocks are exposed at the eastern margin of Tibet due to the interaction between the Indian and Eurasian plates.However,their petrogenesis and associated geodynamic processes remain poorly understood.We analyzed the Xifanping porphyries in the Sanjiang orogenic belt to provide new insights.Our study shows a successive assembly of porphyry intrusions during three magmatic episodes.The magnitude and duration of the magmatic activities diminished sequentially,and mineralization occurred during the intermediate phase.Geochemically,the Xifangping porphyries display an adakitic affinity.According to zircon Hf isotope data,we propose that these porphyries originated from the partial melting of the thickened mafic lower crust beneath the western Yangtze Craton in response to lithospheric extension and asthenospheric upwelling.Analogous to the coeval alkali-rich porphyries in western Yunnan,the petrogenetic model of the Xifanping porphyries indicates regional north-south and east-west fractures caused by the clockwise rotation of the continental lithosphere and the Jinshajiang-Red River strike-slip during the post-collision phase of the India-Eurasia collision.In this context,we argue that the collision in eastern Tibet may have extended eastward to southwestern Sichuan during the post-collision period,persisting until approximately 30 Ma.展开更多
: Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite—porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc—copper alloy mineral fo...: Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite—porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc—copper alloy mineral found for the first time in the porphyry-copper deposit in China. Its intergrown minerals are K—feldspar (mainly perthite), albite—oligoclase, quartz and biotite; and the associated minerals include pyrite and chalcopyrite. It is characterized by a golden reflection colour, being isotropic (isometric), with the grain size ranging from 10 to 50 μm, microhardness VHN10 = 190 kg/mm2, and reflectance RVM = 67.97%. Electron microprobe (Model JXA—733) analysis shows Cu = 59.15%–62.55% and Zn = 36.32%–39.85%. The crystallochemical formula is Cu6.27-7.0Zn4.0, simplified as Cu7Zn4.展开更多
1 Geological features in the deposit THE Xifanping porphyry is located in the Yanyuan-Lijiang fault block at the southern margin of theYangtze massif. Only the Upper Permian Leping Formation and the Lower Triassic Qin...1 Geological features in the deposit THE Xifanping porphyry is located in the Yanyuan-Lijiang fault block at the southern margin of theYangtze massif. Only the Upper Permian Leping Formation and the Lower Triassic Qingtianbao Formation are exposed in Yanyuan County, Sichuan Province. The main ore-bearing rock body (No. 80) is anear-equant irregular complex stock, about 900 m long from east to west and 720 m wide from north tosouth. The bulk part consists of megaphyric biotite-quartz monzonitic porphyry. The commercial orebodylies in the No. 80 rock body and its surrounding country rocks, an N-S-elongated irregular lens-shapeddeposit. The orebody is controlled by the K-feldspar-biotite and quartz-sericite alteration zones. It consists mainly of disseminated and veinlet-disseminated ores.展开更多
基金sponsored by the National Key R&D Project of China(2016YFC0600304)the National Natural Science Foundation of China(42121002)+3 种基金the International Science&Technology Cooperation Program of China(2011DFA22460)China Geological Survey(DD20190370)Geological Exploration Fund of Inner Mongolia Autonomous Region Program(2020YS-01)Major Science and Technology Projects in Yunnan Province(202303AA080006).
文摘Large-scale Cenozoic alkali-rich magmatic rocks are exposed at the eastern margin of Tibet due to the interaction between the Indian and Eurasian plates.However,their petrogenesis and associated geodynamic processes remain poorly understood.We analyzed the Xifanping porphyries in the Sanjiang orogenic belt to provide new insights.Our study shows a successive assembly of porphyry intrusions during three magmatic episodes.The magnitude and duration of the magmatic activities diminished sequentially,and mineralization occurred during the intermediate phase.Geochemically,the Xifangping porphyries display an adakitic affinity.According to zircon Hf isotope data,we propose that these porphyries originated from the partial melting of the thickened mafic lower crust beneath the western Yangtze Craton in response to lithospheric extension and asthenospheric upwelling.Analogous to the coeval alkali-rich porphyries in western Yunnan,the petrogenetic model of the Xifanping porphyries indicates regional north-south and east-west fractures caused by the clockwise rotation of the continental lithosphere and the Jinshajiang-Red River strike-slip during the post-collision phase of the India-Eurasia collision.In this context,we argue that the collision in eastern Tibet may have extended eastward to southwestern Sichuan during the post-collision period,persisting until approximately 30 Ma.
文摘: Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite—porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc—copper alloy mineral found for the first time in the porphyry-copper deposit in China. Its intergrown minerals are K—feldspar (mainly perthite), albite—oligoclase, quartz and biotite; and the associated minerals include pyrite and chalcopyrite. It is characterized by a golden reflection colour, being isotropic (isometric), with the grain size ranging from 10 to 50 μm, microhardness VHN10 = 190 kg/mm2, and reflectance RVM = 67.97%. Electron microprobe (Model JXA—733) analysis shows Cu = 59.15%–62.55% and Zn = 36.32%–39.85%. The crystallochemical formula is Cu6.27-7.0Zn4.0, simplified as Cu7Zn4.
文摘1 Geological features in the deposit THE Xifanping porphyry is located in the Yanyuan-Lijiang fault block at the southern margin of theYangtze massif. Only the Upper Permian Leping Formation and the Lower Triassic Qingtianbao Formation are exposed in Yanyuan County, Sichuan Province. The main ore-bearing rock body (No. 80) is anear-equant irregular complex stock, about 900 m long from east to west and 720 m wide from north tosouth. The bulk part consists of megaphyric biotite-quartz monzonitic porphyry. The commercial orebodylies in the No. 80 rock body and its surrounding country rocks, an N-S-elongated irregular lens-shapeddeposit. The orebody is controlled by the K-feldspar-biotite and quartz-sericite alteration zones. It consists mainly of disseminated and veinlet-disseminated ores.
