Western Yunnan is the well-known polymetallic province in China. It is characterized by copper-gold mineralization related to Cenozoic alkali-rich porphyry. This paper analyzes the silicon isotope data obtained from f...Western Yunnan is the well-known polymetallic province in China. It is characterized by copper-gold mineralization related to Cenozoic alkali-rich porphyry. This paper analyzes the silicon isotope data obtained from four typical alkali-rich porphyry deposits based on the dynamic fractionation principle of silicon isotope. The study shows that the ore materials should originate mainly from alkali-rich magmas, together with silicon-rich mineralizing fluids. The process of mineralization was completed by auto-metasomatism, i.e. silicon-rich mineralizing fluids (including alkali-rich porphyry and wall-rock strata) replaced and altered the country rocks and contaminated with crustal rocks during the crystallization of alkali-rich magmas. Such a process is essentially the continuance of the metasomatism of mantle fluids in crust's mineralization. This provides important evidence of silicon isotopic geochemistry for better understanding the mineralization of the Cenozoic alkali-rich porphyry polymetallic deposits展开更多
New zircon U–Pb ages, whole-rock geochemistry and zircon Hf isotopes from the Habo porphyry Western Yunnan, China, were determined to provide constraints on the timing of uplift of the Eastern Tibetan Plateau. The in...New zircon U–Pb ages, whole-rock geochemistry and zircon Hf isotopes from the Habo porphyry Western Yunnan, China, were determined to provide constraints on the timing of uplift of the Eastern Tibetan Plateau. The intrusive rocks consist of shoshonitic porphyry（syenite porphyry and monzonite porphyry）. Zircon laser ablation inductively coupled plasma mass spectrometry（LA-ICPMS） U–Pb dating indicates coeval emplacement ages of ～35 Ma. The porphyries have alkaline affinities, enrichment in large ion lithophile elements（LILEs） and light rare earth elements（LREEs）（e.g., Rb, Th, U, Pb）, with depletion of high field strength elements（HFSEs）（e.g., Nb, Ti, Ta） and weak Eu anomalies. They display uniform Lu–Hf isotopic compositions with negative zircon εHf（t） values ranging from-3.9 to-0.6. The chemical characteristics of the syenite porphyries indicated that they most likely originated from the lower crust, with mantle-derived material involved in their generation. Geochemically, the monzonite porphyries are similar to the syenite porphyries; however, the lower MgO contents suggest that they were produced by different degrees of partial melting of the same lower crust source. Combined with the geochemical and isotopic data in this paper, imply that the alkali-rich porphyries of the Habo polymetallic deposit were derived from the partial melting of lower crust, enriched by mantle magma, formed in a conversion stage from stress extrusion（a strike-slip shear process） to local stress relaxation（a strike-slip pull-apart process） at the Ailaoshao tectonic zone.展开更多
SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies ...SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies occur extensively and the porphyry-related polymetallic mineral resources are produced. Manystudies on the petrology and geochemistry of the alkali-rich porphyry have been carried out and thegenerally accepted conclusion is that the petrogenesis material source has something to do with the enriched source in the mantle. The integrated interactive factors of the mineralization related to the alkalirich porphyry consist in the favourable combination of the mantle fluid metasomatism, which is derivedfrom the deep processes, and the conducting and controlling roles of the large-scale deep faults. Alongwith the changes in physical and chemical conditions caused by the diffusion of the ore-forming展开更多
文摘Western Yunnan is the well-known polymetallic province in China. It is characterized by copper-gold mineralization related to Cenozoic alkali-rich porphyry. This paper analyzes the silicon isotope data obtained from four typical alkali-rich porphyry deposits based on the dynamic fractionation principle of silicon isotope. The study shows that the ore materials should originate mainly from alkali-rich magmas, together with silicon-rich mineralizing fluids. The process of mineralization was completed by auto-metasomatism, i.e. silicon-rich mineralizing fluids (including alkali-rich porphyry and wall-rock strata) replaced and altered the country rocks and contaminated with crustal rocks during the crystallization of alkali-rich magmas. Such a process is essentially the continuance of the metasomatism of mantle fluids in crust's mineralization. This provides important evidence of silicon isotopic geochemistry for better understanding the mineralization of the Cenozoic alkali-rich porphyry polymetallic deposits
基金financially supported by the National Natural Science Foundation of China(41372208 and 41776056)Natural Science Foundation of Guangdong Province(2017A030310395)
文摘New zircon U–Pb ages, whole-rock geochemistry and zircon Hf isotopes from the Habo porphyry Western Yunnan, China, were determined to provide constraints on the timing of uplift of the Eastern Tibetan Plateau. The intrusive rocks consist of shoshonitic porphyry（syenite porphyry and monzonite porphyry）. Zircon laser ablation inductively coupled plasma mass spectrometry（LA-ICPMS） U–Pb dating indicates coeval emplacement ages of ～35 Ma. The porphyries have alkaline affinities, enrichment in large ion lithophile elements（LILEs） and light rare earth elements（LREEs）（e.g., Rb, Th, U, Pb）, with depletion of high field strength elements（HFSEs）（e.g., Nb, Ti, Ta） and weak Eu anomalies. They display uniform Lu–Hf isotopic compositions with negative zircon εHf（t） values ranging from-3.9 to-0.6. The chemical characteristics of the syenite porphyries indicated that they most likely originated from the lower crust, with mantle-derived material involved in their generation. Geochemically, the monzonite porphyries are similar to the syenite porphyries; however, the lower MgO contents suggest that they were produced by different degrees of partial melting of the same lower crust source. Combined with the geochemical and isotopic data in this paper, imply that the alkali-rich porphyries of the Habo polymetallic deposit were derived from the partial melting of lower crust, enriched by mantle magma, formed in a conversion stage from stress extrusion（a strike-slip shear process） to local stress relaxation（a strike-slip pull-apart process） at the Ailaoshao tectonic zone.
文摘SANJING region (the region of three rivers, i.e. Jinsha-Lanchang-Nujiang rivers) is a very active Cenozoicinterplate deformation area on the east margin of Qinghai-Xizang Plateau, where the alkali-rich porphyrybodies occur extensively and the porphyry-related polymetallic mineral resources are produced. Manystudies on the petrology and geochemistry of the alkali-rich porphyry have been carried out and thegenerally accepted conclusion is that the petrogenesis material source has something to do with the enriched source in the mantle. The integrated interactive factors of the mineralization related to the alkalirich porphyry consist in the favourable combination of the mantle fluid metasomatism, which is derivedfrom the deep processes, and the conducting and controlling roles of the large-scale deep faults. Alongwith the changes in physical and chemical conditions caused by the diffusion of the ore-forming
