Primitive mantle normalized Platinum group elements (PGE) concentration patterns for the Zhengziyanwo intrusion and Dashibao Formation basalts are of positive slope, similar to most of the world class magmatic Ni Cu P...Primitive mantle normalized Platinum group elements (PGE) concentration patterns for the Zhengziyanwo intrusion and Dashibao Formation basalts are of positive slope, similar to most of the world class magmatic Ni Cu PGE sulfide deposits. Characters of this intrusion and its related ores and Dashibao Formation basalts are their negative Pt anomaly and high concentration of Rh relative to Pt and Pd, facts being interpreted to be the results of crystallization and fractionation of Pt alloys and spinel phase free crystallization history for the magma, respectively. PGE parameters of the Dashibao Formation basalts are consistent with the general trend of those found for the Zhengziyanwo intrusion, and this might infer a genetic link between them.展开更多
The Jinchuan magmatic Ni-Cu deposit,located in the Longshou Mountain region,is the largest producer of Ni and Cu in China,with mineralization being related to mafic and ultramafic magmatism.Previous studies have shown...The Jinchuan magmatic Ni-Cu deposit,located in the Longshou Mountain region,is the largest producer of Ni and Cu in China,with mineralization being related to mafic and ultramafic magmatism.Previous studies have shown that the Longshou Mountain was combined with the Qilian Mountains before Neoproterozoic,and was separated from each other due to the opening of late Qilian oceanic basin in the Paleozoic.The relict Precambrian microcontinents of the Longshou Mountain and Qilian Mountain展开更多
Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by ...Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by the Cadomian orogenic belt.Pancarli sulfides are associated with quartzo-feldspathic gneisses(country rock)and mafic intrusions(host rock).Composed of only semi-massive ore,the Ni-Cu±(PGE)sulfide deposit is a small-scale deposit,and it does not contain net-textured and disseminated ore.The mineral assemblage comprises pyrrhotite,pentlandite,and chalcopyrite.The semi-massive ore samples contain 2.2 wt.%-2.9 wt.%Ni,0.8 wt.%-2.2 wt.%Cu(Cu/(Cu+Ni)=0.2-0.5)and 0.13 wt.%-0.17 wt.%Co.The Cu/Ni ratios(average 0.57)are consistent with the segregation of sulfides from a basaltic magma.Low Pt+Pd100%S values of 0.08 ppm-0.89 ppm,relatively low Pt/Pd ratios of 0.2-1.4,and Pd/Ir ratios of 4.5-39 have also been revealed.These values demonstrate that the magma reached S saturation before its emplacement and the mineralization with high Cu/Pd ratios formed by sulfides segregated from a PGE-depleted magma.δ^34S isotope values(average-3.1‰)of Pancarli sulfides are lower than mantle source.Negativeδ^34S value indicates contamination from surrounding rocks.Concerning the composition,remobilization style and magma type,the Pancarli Ni-Cu±(PGE)sulfide deposit is similar to the deposits associated with Andean-type magmatic arcs located in the convergent plate margin settings.展开更多
The Qingkuangshan Ni-Cu-PGE deposit, located in the Xiaoguanhe region of Huili County, Sichuan Province, is one of several Ni-Cu-PGE deposits in the Emeishan Large Igneous Province (ELIP). The ore-bearing intrusion is...The Qingkuangshan Ni-Cu-PGE deposit, located in the Xiaoguanhe region of Huili County, Sichuan Province, is one of several Ni-Cu-PGE deposits in the Emeishan Large Igneous Province (ELIP). The ore-bearing intrusion is a mafic-ultramafic body. This paper reports major elements, trace elements and platinum-group elements in different types of rocks and sulfide-mineralized samples in the intrusion. These data are used to evaluate the source mantle characteristics, the degree of mantle partial melting, the composition of parental magma and the ore-forming processes. The results show that Qingkuangshan intrusion is part of the ELIP. The rocks have trace element ratios similar to the coeval Emeishan basalts. The primitive mantle-normalized patterns of Ni-Cu-PGE have positive slopes, and the ratios of Pd/Ir are lower than 22. The PGE compositions of sulfide ores and associated rocks are characterized by Ru depletion. The PGE contents in bulk sulfides are slightly depleted relative to Ni and Cu, which is similar to the Yangliuping Ni-Cu-PGE deposit. The composition of the parental magma for the intrusion is estimated to contain about 14.65 wt% MgO, 48.66 wt% SiO2 and 15.48 wt% FeOt, and the degree of mantle partial melting is estimated to be about 20%. In comparison with other typical Ni-Cu-PGE deposits in the ELIP, the Qingkuangshan Ni-Cu-PGE deposit has lower PGE contents than the Jinbaoshan PGE deposit, but has higher PGE contents than the Limahe and Baimazhai Ni-Cu deposit, and has similar PGE contents to the Yangliuping Ni-Cu-PGE deposit. The moderate PGE depletions in the bulk sulfide of the Qingkuanghan deposit suggest that the parental magma of the host intrusion may have undergone minor sulfide segregation at depth. The mixing calculations suggests that an average of 10% crustal contamination in the magma, which may have been the main cause of sulfide saturation in the magma. We propose that sulfide segregation from a moderately PGE depleted magma took place prior to magma emplacement at Qingkuangshan, that small amounts of immiscible sulfide droplets and olivine and chromite crystals were suspended in the ascending magma, and that the suspended materials settled down when the magma passed trough the Qingkuangshan conduit. The Qingkuangshan sulfide-bearing intrusion is interpreted to a feeder of Emeishan flood basalts in the region.展开更多
The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments o...The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments of a single elongate intrusion that was dismembered by late faults into eastern and western portions,each of which have distinct stratigraphic sequences.展开更多
通过2009年西安Ni-Cu(Pt)岩浆矿床国际学术研讨会和近10年来的勘查研究现状,可以看出岩浆硫化物矿床勘查领域的发展趋势为:与大型层状岩体有关的铂族矿床仍然受到关注;Sudbury矿床的特殊性和不可参照性取得了共识;小岩体矿床是勘查研究...通过2009年西安Ni-Cu(Pt)岩浆矿床国际学术研讨会和近10年来的勘查研究现状,可以看出岩浆硫化物矿床勘查领域的发展趋势为:与大型层状岩体有关的铂族矿床仍然受到关注;Sudbury矿床的特殊性和不可参照性取得了共识;小岩体矿床是勘查研究的主流;通道成矿作用受到重视。以大型层状岩体Bushveld为例,介绍了其中的Merensky矿层、UG-2矿层和北翼接触带的Platreef矿床。由于中国没有发现这种大型层状岩体,因此应当重视那些中小型层状岩体中可能赋存的铂族矿床。迄今为止,除了Sudbury矿床这个特殊的实例之外,国内外所有具有经济意义的Ni-Cu矿床都寄生于小岩体中并自成一个成矿系统。这个小岩体成矿系统包含成矿背景、邻近深大断裂、原始岩浆、先导性岩浆成岩作用、继发性岩浆成矿作用以及深部熔离-分期贯入-终端岩浆房聚集成矿等。近10年的勘查实践进一步说明,这类小岩体矿床仍是中国今后的主要勘查研究方向。最后,介绍了Noril sk-Talnakh和Voisey s Bay矿床的深部熔离-通道成矿机制,这种机制增添了小岩体成矿作用的多样性;但是,其现存空间是开放性岩浆通道还是封闭性终端岩浆房,还有待更多的研究和实践。展开更多
基金supported by NSFC(Grant Nos.40072037,40273025)NKBRSF Project(Grant No.G1999043200)
文摘Primitive mantle normalized Platinum group elements (PGE) concentration patterns for the Zhengziyanwo intrusion and Dashibao Formation basalts are of positive slope, similar to most of the world class magmatic Ni Cu PGE sulfide deposits. Characters of this intrusion and its related ores and Dashibao Formation basalts are their negative Pt anomaly and high concentration of Rh relative to Pt and Pd, facts being interpreted to be the results of crystallization and fractionation of Pt alloys and spinel phase free crystallization history for the magma, respectively. PGE parameters of the Dashibao Formation basalts are consistent with the general trend of those found for the Zhengziyanwo intrusion, and this might infer a genetic link between them.
文摘The Jinchuan magmatic Ni-Cu deposit,located in the Longshou Mountain region,is the largest producer of Ni and Cu in China,with mineralization being related to mafic and ultramafic magmatism.Previous studies have shown that the Longshou Mountain was combined with the Qilian Mountains before Neoproterozoic,and was separated from each other due to the opening of late Qilian oceanic basin in the Paleozoic.The relict Precambrian microcontinents of the Longshou Mountain and Qilian Mountain
基金supported by the General Directorate of Mineral Research and Exploration。
文摘Pancarli Ni-Cu±(PGE)sulfide deposit occurs in the Neoproterozoic basement complex of the Bitlis massif,which is one of the Andean-type active continental margin fragments with arc-type assemblages represented by the Cadomian orogenic belt.Pancarli sulfides are associated with quartzo-feldspathic gneisses(country rock)and mafic intrusions(host rock).Composed of only semi-massive ore,the Ni-Cu±(PGE)sulfide deposit is a small-scale deposit,and it does not contain net-textured and disseminated ore.The mineral assemblage comprises pyrrhotite,pentlandite,and chalcopyrite.The semi-massive ore samples contain 2.2 wt.%-2.9 wt.%Ni,0.8 wt.%-2.2 wt.%Cu(Cu/(Cu+Ni)=0.2-0.5)and 0.13 wt.%-0.17 wt.%Co.The Cu/Ni ratios(average 0.57)are consistent with the segregation of sulfides from a basaltic magma.Low Pt+Pd100%S values of 0.08 ppm-0.89 ppm,relatively low Pt/Pd ratios of 0.2-1.4,and Pd/Ir ratios of 4.5-39 have also been revealed.These values demonstrate that the magma reached S saturation before its emplacement and the mineralization with high Cu/Pd ratios formed by sulfides segregated from a PGE-depleted magma.δ^34S isotope values(average-3.1‰)of Pancarli sulfides are lower than mantle source.Negativeδ^34S value indicates contamination from surrounding rocks.Concerning the composition,remobilization style and magma type,the Pancarli Ni-Cu±(PGE)sulfide deposit is similar to the deposits associated with Andean-type magmatic arcs located in the convergent plate margin settings.
基金financially supported by the Chinese Academy of Sciences (grant no.KZCX2-YW-Q04-06)the National Key Basic Research Program of China (grant no. 2009CB421005)the National Science Foundation of China (grant no.40973039)
文摘The Qingkuangshan Ni-Cu-PGE deposit, located in the Xiaoguanhe region of Huili County, Sichuan Province, is one of several Ni-Cu-PGE deposits in the Emeishan Large Igneous Province (ELIP). The ore-bearing intrusion is a mafic-ultramafic body. This paper reports major elements, trace elements and platinum-group elements in different types of rocks and sulfide-mineralized samples in the intrusion. These data are used to evaluate the source mantle characteristics, the degree of mantle partial melting, the composition of parental magma and the ore-forming processes. The results show that Qingkuangshan intrusion is part of the ELIP. The rocks have trace element ratios similar to the coeval Emeishan basalts. The primitive mantle-normalized patterns of Ni-Cu-PGE have positive slopes, and the ratios of Pd/Ir are lower than 22. The PGE compositions of sulfide ores and associated rocks are characterized by Ru depletion. The PGE contents in bulk sulfides are slightly depleted relative to Ni and Cu, which is similar to the Yangliuping Ni-Cu-PGE deposit. The composition of the parental magma for the intrusion is estimated to contain about 14.65 wt% MgO, 48.66 wt% SiO2 and 15.48 wt% FeOt, and the degree of mantle partial melting is estimated to be about 20%. In comparison with other typical Ni-Cu-PGE deposits in the ELIP, the Qingkuangshan Ni-Cu-PGE deposit has lower PGE contents than the Jinbaoshan PGE deposit, but has higher PGE contents than the Limahe and Baimazhai Ni-Cu deposit, and has similar PGE contents to the Yangliuping Ni-Cu-PGE deposit. The moderate PGE depletions in the bulk sulfide of the Qingkuanghan deposit suggest that the parental magma of the host intrusion may have undergone minor sulfide segregation at depth. The mixing calculations suggests that an average of 10% crustal contamination in the magma, which may have been the main cause of sulfide saturation in the magma. We propose that sulfide segregation from a moderately PGE depleted magma took place prior to magma emplacement at Qingkuangshan, that small amounts of immiscible sulfide droplets and olivine and chromite crystals were suspended in the ascending magma, and that the suspended materials settled down when the magma passed trough the Qingkuangshan conduit. The Qingkuangshan sulfide-bearing intrusion is interpreted to a feeder of Emeishan flood basalts in the region.
文摘The Jinchuan Ni-Cu sulfide deposits,NW China,are hosted in small ultramafic intrusions that were emplaced into Paleoproterozoic metamorphic rocks. The ultramafic intrusions were previously thought to be the segments of a single elongate intrusion that was dismembered by late faults into eastern and western portions,each of which have distinct stratigraphic sequences.
文摘通过2009年西安Ni-Cu(Pt)岩浆矿床国际学术研讨会和近10年来的勘查研究现状,可以看出岩浆硫化物矿床勘查领域的发展趋势为:与大型层状岩体有关的铂族矿床仍然受到关注;Sudbury矿床的特殊性和不可参照性取得了共识;小岩体矿床是勘查研究的主流;通道成矿作用受到重视。以大型层状岩体Bushveld为例,介绍了其中的Merensky矿层、UG-2矿层和北翼接触带的Platreef矿床。由于中国没有发现这种大型层状岩体,因此应当重视那些中小型层状岩体中可能赋存的铂族矿床。迄今为止,除了Sudbury矿床这个特殊的实例之外,国内外所有具有经济意义的Ni-Cu矿床都寄生于小岩体中并自成一个成矿系统。这个小岩体成矿系统包含成矿背景、邻近深大断裂、原始岩浆、先导性岩浆成岩作用、继发性岩浆成矿作用以及深部熔离-分期贯入-终端岩浆房聚集成矿等。近10年的勘查实践进一步说明,这类小岩体矿床仍是中国今后的主要勘查研究方向。最后,介绍了Noril sk-Talnakh和Voisey s Bay矿床的深部熔离-通道成矿机制,这种机制增添了小岩体成矿作用的多样性;但是,其现存空间是开放性岩浆通道还是封闭性终端岩浆房,还有待更多的研究和实践。
