I.GEOLOGICAL SETTING OF THE BASIC-ULTRABASIC COMPLEX The Yanbian basic-ultrabasic complex is situated on the west edge of the middle section of the Chuan Dian (Sichuan Yunnan) SN-trending tectonic zone, intruding the ...I.GEOLOGICAL SETTING OF THE BASIC-ULTRABASIC COMPLEX The Yanbian basic-ultrabasic complex is situated on the west edge of the middle section of the Chuan Dian (Sichuan Yunnan) SN-trending tectonic zone, intruding the unconformable contact zone between the Archeozoic Kangding complex and the Presinian Yanbian group. The country rocks of the complex are magmatic and regional metamorphic rocks. The complex is stretched NW, irregularly ellipsoidal in shape, 9 km in length (SN)展开更多
Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+...Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant diagrams distribution areas of the characteristic values of ore-free melt and those of ore-forming melt are overlapped in different degrees, which possibly indicates that not all the magmas have mineralizing ability. It can be well distinguished whether basic-ultrabasic rocks are favourable to Cu or Au mineralization or they are just ore-free rocks by analysing integrated diagrams of the characteristic values of the magmatic melt structure.展开更多
The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies,...The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.展开更多
文摘I.GEOLOGICAL SETTING OF THE BASIC-ULTRABASIC COMPLEX The Yanbian basic-ultrabasic complex is situated on the west edge of the middle section of the Chuan Dian (Sichuan Yunnan) SN-trending tectonic zone, intruding the unconformable contact zone between the Archeozoic Kangding complex and the Presinian Yanbian group. The country rocks of the complex are magmatic and regional metamorphic rocks. The complex is stretched NW, irregularly ellipsoidal in shape, 9 km in length (SN)
文摘Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant diagrams distribution areas of the characteristic values of ore-free melt and those of ore-forming melt are overlapped in different degrees, which possibly indicates that not all the magmas have mineralizing ability. It can be well distinguished whether basic-ultrabasic rocks are favourable to Cu or Au mineralization or they are just ore-free rocks by analysing integrated diagrams of the characteristic values of the magmatic melt structure.
文摘The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260～250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.
