The Yangla copper deposit, located in western Yunnan Province, China, is a typical giant, newly started mining copper deposit with an estimated Cu reserves of about 1,200,000 tons. The deposit is spatially and tempora...The Yangla copper deposit, located in western Yunnan Province, China, is a typical giant, newly started mining copper deposit with an estimated Cu reserves of about 1,200,000 tons. The deposit is spatially and temporally associated with the Linong granodiorite, which is rich in SiO2 （SIO2=58.25 wt%-69.84 wt%） and alkalis （Na20＋K20=5.98 wt%-8.34 wt%）, indicating an association with shoshonitic series to high-K calc-alkaline series granites, and shows low contents of TiO2 （0.35 wt%- 0.48 wt%）, MgO （1.51 wt%-1.72 wt%）, and A1203 （13.38 wt%-19.75 wt%）. The 34S values of sulfides of the main ore stage from copper ores vary range from -4.2%o to -0.9%o, indicating a much greater contribution from the mantle to the ore-forming fluids. The 34S values of the late ore stage is -9.8%0, indicating enrichment of biogenic sulfur which may derive from the crustal hydrothermal fluid. The 208pb/204pb, 207pb/204pb and 206pb/204pb of sulfides of the main ore stage from copper ores range within 38.66-38.73, 15.71-15.74 and 18.35-19.04, respectively, implying that the Pb was derived from the mantle, with the crustal component, probably representing mixtures of mantle lead and crustal lead. Sulfide of the late ore stage in their Pb isotopic composition, 208pb/204pb= 38.69, 207pb/204pb=15.70, 206Pb/204pb=18.35, implying that the Pb was derived from the crust. The Linong granodiorite is syn- collisional, produced by partial melting of thickened lower crust, which was triggered by the westward subduction of the Jinshajiang Oceanic plate. During a transition in geodynamic setting from collision- related compression to extension, gently dipping ductile shear zones （related to subduction） were transformed to brittle shear zones, consisting of a series of thrust faults in the Jinshajiang tectonic belt. The tensional thrust faults would have been a favorable environment for ore-forming fluids. The ascending magma provided a channel for the ore-forming fluid from the mantle wedge. After the magma arrived at the base of the early-stage Linong granodiorite, the platy granodiorite at the base of the body would have shielded the late-stage magma from the fluid. The magma would have cooled slowly, and some of the ore-forming fluid in the magma would have entered the gently dipping thrust faults near the Linong granodiorite, resulting in mineralization.展开更多
Yangla copper deposit is the largest banded skarn hosted copper deposit found recently in the Tethys orogenic belt of Southwestern China. On the basis of the study of distribution, petrology and mineralogy as well as...Yangla copper deposit is the largest banded skarn hosted copper deposit found recently in the Tethys orogenic belt of Southwestern China. On the basis of the study of distribution, petrology and mineralogy as well as major element, REE and isotope geochemistry, the authors find that the banded skarn, which hosts the deposit, was precipitated from hydrothermal solutions in the form of exhalate sediment. Therefore, the banded skarn hosted copper deposit is a Sedex type deposit, with a series of stacked, conformable lenses underlain by at least one stringer zone. The deposit, intercalated at the contact of lower clastic rock and upper carbonate rock of Gajinxueshan Group, was formed in the Carboniferous ((296.1±7.0) Ma), contemporary to the host Gajinxueshan Group. The interpretation of the genesis of Yangla banded skarn hosted copper deposit is of fundamental exploration significance for the discovery of Sedex type copper deposit in the region.展开更多
The Yangla Cu deposit is the largest ore deposit in the Jinshajiang polymetallic metallogenic belt,northwest Yunnan,China.There is no consensus on the genesis of the ore deposit owing to the limited studies on the che...The Yangla Cu deposit is the largest ore deposit in the Jinshajiang polymetallic metallogenic belt,northwest Yunnan,China.There is no consensus on the genesis of the ore deposit owing to the limited studies on the chemical compositions of sulfides.This study used an electron probe micro-analyzer to constrain the chemical compositions of pyrite,chalcopyrite,molybdenite,and sphalerite in the porphyry Cu ore of the Yangla Cu deposit and compared them with the chemical compositions of sulfides in the skarn Cu ore.The trace element contents and their occurrences were used to estimate the metallogenic temperature and infer the genesis of the Yangla deposit.The results show that the sulfides in the porphyry Cu ores have variations of ore element concentrations relative to their theoretical values.Pyrite is depleted in S but elevated in Fe;chalcopyrite is depleted in Cu,Fe,and S;and molybdenite and sphalerite are enriched in S whilst depleted in Mo and Zn.The concentrations of the main metallogenic elements Cu,Fe,Mo,Zn,and S in the porphyry are generally lower than those in skarn,suggesting that the porphyry ore was formed in a moderate to moderate-high temperature metallogenic environment.The formation time may also be slightly later than that of the skarn Cu ore.Elements such as As,Co,Cu.Pb,Zn,Mo,Cd,and Ni mainly exist as isomorphic replacements and mineral inclusions in the sulfides of both porphyry and skarn Cu ores.The trace element features of sulfides in the two ore bodies show that the Yangla Cu deposit may be a composite super imposed ore deposit,and让s formation has undergone the process of exhalative-sedimentary to skarnporphyry mineralization.展开更多
The large-scale Yangla copper deposit, located in the central part of the Sanjiang Tethys polymetallic belt, is structurally controlled by the Jinsha River Fault and Yangla Fault. This deposit consists of seven ore bl...The large-scale Yangla copper deposit, located in the central part of the Sanjiang Tethys polymetallic belt, is structurally controlled by the Jinsha River Fault and Yangla Fault. This deposit consists of seven ore blocks, including the Beiwu, Nilv, Jiangbian, Linong, Lunong, Tongjige and Jiaren. The Cu metal prospective reserves of the Yangla deposit are above 1 million tons. There are widely distributed Indosinian granodiorite and also many gabbro-diabase dikes and few quartz porphyries exposed in the Yangla ore district. The ore-hosting rocks are diopsode-garnet skarn, sericitie sandy slate and metamorphic quartz sandstone of the first member of the Devonian Linong Formation. Ore bodies occur as layered, stratoid, lenticular and veined shapes, and are strictly controlled by rocks, strata and structures.展开更多
The Yangla Copper Ore Field in Northwest Yunnan Province, China, is a large region of deposits dominated by copper-bearing skarns whose origin remains debatable despite numerous studies over the past two decades. We h...The Yangla Copper Ore Field in Northwest Yunnan Province, China, is a large region of deposits dominated by copper-bearing skarns whose origin remains debatable despite numerous studies over the past two decades. We have investigated the geological and geochemical characteristics of the skarns using field and microscopic observations combined with chemical analyses. The results show that the skarns fall into two categories. The first category is metamorphic skarn, which constitute the majority （〉90%） of skarns in the deposit and is characterized by stratiform occurrences conformable to Devonian host strata, anhydrous mineral assemblages such as diopside＋hedenbergite＋quartz, widespread banded structure, fine-grainsize （〈200 μm） and preserved tuff-like textures. Whole-rock major element compositions, REE and trace-element compositions resemble those of the country rock slates or schists. The skarn layers occur at variable distances （0-2 000 m） from Indosinian plutonic bodies. Fracture-filling veins and/or alteration halos are scarce or absent in or near the skarn layers. This category of skarn probably formed by isochemical contact metamorphism of fine calcareous clastic sediments or impure carbonate rocks during emplacement of the plutonic bodies with no significant material migration by hydrothermal fluids involved during the process, in which case metallic enrichment of the skarn layers was present in the protolith of the skarn. The second category is metasomatic skarn with relatively coarse-grained textures （200-〉1 000 μm） and volatile-reach assemblages such as diopside＋tremolite＋scapolite at or near the igneous contact zones, which constitutes only a minor pro-portion of ore compared with metamorphic skarn. Taking into consideration diverse existing opinions about the genetic type of the deposit, we suggest that the geological and whole-rock geochemical characteristics of the skarus are consistent with a metamorphosed and metasomatized SEDEX （sedimentary exhalative deposit） type rather than a hydrothermal metasomatic skarn type.展开更多
The Yangla Cu skarn deposit is located in the central part of the Jinshajiang Suture Zone,southwest China,with a total reserve of 150 Mt Cu@1.03%.The newly discovered antimony orebodies at the depth of Yangla are stri...The Yangla Cu skarn deposit is located in the central part of the Jinshajiang Suture Zone,southwest China,with a total reserve of 150 Mt Cu@1.03%.The newly discovered antimony orebodies at the depth of Yangla are strictly controlled by the stratum,structure,and lithology,which are lenticular and vein-like within the marble fracture zone,which can provide a window into multistage miner-alization and ore genesis at Yangla.Mineralization can be divided into three types,Cu–Pb–Zn(skarn)pyrite,galena,and sphalerite,Cu(porphyry)chalcopyrite and pyrite,and Sb(hydrothermal)stibnite and pyrite.The mineral assem-blages were stibnite+pyrite+calcite+quartz±minor scheelite in antimony ores.This study presents quantitative measurements of the trace element compositions of pyrite and stibnite from the Yangla antimony ores.Analysis of pyrite with electron probe microanalysis(EPMA)showed enrichment in Co,Ni,Sb,As,and Mo,and deficit in its S and Fe contents when compared to the stoichiometric con-centrations of S and Fe in pyrite.The Sb-related pyrite may belong to sedimentary-reworked genesis and may be modi-fied by hydrothermalfluids,thereby presenting a certain dif-ference(i.e.,crystal morphology,texture,and chemical com-position)compared to the skarn and porphyry Cu-related pyrite in the Yangla Cu skarn deposit.Analysis of stibnite with EPMA and inductively coupled plasma-mass spectrom-etry showed enrichment in As,Pb,Sn,Pb,Cu,and Zn,and presented much higher Sb contents and slightly lower S con-tents when compared to the stoichiometric concentrations of Sb and S in stibnite.Statistical analysis of the stibnite trace elements showed correlations for the elemental pairs Cu–Pb,As–Sb,and Sn–Pb,and the coupled substitution equations Sb^(3+)↔Cu^(+)+Pb^(2+),Sb^(3+)↔As^(3+),and Sn^(2+)↔Pb^(2+)may be the major factors governed the incorporating Cu,Pb,As and Sn within the stibnite.Moreover,this study preliminary shows that the antimony mineralization may belong to a car-bonate replacement hydrothermal genesis at Yangla.展开更多
Four layers of cherts were found for the first time in the Yangla copper deposit, western Yunnan Province. The cherts possessed the following geochemical characteristics: 1 Low TiO2 and Al2O3 contents, but high ore-fo...Four layers of cherts were found for the first time in the Yangla copper deposit, western Yunnan Province. The cherts possessed the following geochemical characteristics: 1 Low TiO2 and Al2O3 contents, but high ore-forming element (e.g. Cu, Au, Ag) contents; 2 low total REE contents and clear negative Eu anomalies when normalized to chondrite similar to the REE contents and distribution patterns of associated massive sulfide ores; 3 silicon isotopic compositions of cherts in the Yangla deposit being the same as cherts and geyserite of hot-water sedimentary origin; 4 lead and sulfur isotopic compositions of cherts in the Yangla deposit being similar to those of the massive sulfide ores in the Yangla deposit; 5 Rb-Sr isochron age of cherts from the Yangla deposit being identical with that of host strata. Hence, we conclude that the cherts in the Yangla deposit are of hot-water sedimentary origin, which have a close relationship with the massive sulfide ores. The discovery of hydrothermal cherts from the Yangla copper deposit provides further evidence for the hydrothermal exhalative origin of the massive sulfide deposits.展开更多
基金supported by the National Basic Research Program of China (2009CB421003,2009CB421005)by the 111 Project (Grant No. B07011)
文摘The Yangla copper deposit, located in western Yunnan Province, China, is a typical giant, newly started mining copper deposit with an estimated Cu reserves of about 1,200,000 tons. The deposit is spatially and temporally associated with the Linong granodiorite, which is rich in SiO2 （SIO2=58.25 wt%-69.84 wt%） and alkalis （Na20＋K20=5.98 wt%-8.34 wt%）, indicating an association with shoshonitic series to high-K calc-alkaline series granites, and shows low contents of TiO2 （0.35 wt%- 0.48 wt%）, MgO （1.51 wt%-1.72 wt%）, and A1203 （13.38 wt%-19.75 wt%）. The 34S values of sulfides of the main ore stage from copper ores vary range from -4.2%o to -0.9%o, indicating a much greater contribution from the mantle to the ore-forming fluids. The 34S values of the late ore stage is -9.8%0, indicating enrichment of biogenic sulfur which may derive from the crustal hydrothermal fluid. The 208pb/204pb, 207pb/204pb and 206pb/204pb of sulfides of the main ore stage from copper ores range within 38.66-38.73, 15.71-15.74 and 18.35-19.04, respectively, implying that the Pb was derived from the mantle, with the crustal component, probably representing mixtures of mantle lead and crustal lead. Sulfide of the late ore stage in their Pb isotopic composition, 208pb/204pb= 38.69, 207pb/204pb=15.70, 206Pb/204pb=18.35, implying that the Pb was derived from the crust. The Linong granodiorite is syn- collisional, produced by partial melting of thickened lower crust, which was triggered by the westward subduction of the Jinshajiang Oceanic plate. During a transition in geodynamic setting from collision- related compression to extension, gently dipping ductile shear zones （related to subduction） were transformed to brittle shear zones, consisting of a series of thrust faults in the Jinshajiang tectonic belt. The tensional thrust faults would have been a favorable environment for ore-forming fluids. The ascending magma provided a channel for the ore-forming fluid from the mantle wedge. After the magma arrived at the base of the early-stage Linong granodiorite, the platy granodiorite at the base of the body would have shielded the late-stage magma from the fluid. The magma would have cooled slowly, and some of the ore-forming fluid in the magma would have entered the gently dipping thrust faults near the Linong granodiorite, resulting in mineralization.
文摘Yangla copper deposit is the largest banded skarn hosted copper deposit found recently in the Tethys orogenic belt of Southwestern China. On the basis of the study of distribution, petrology and mineralogy as well as major element, REE and isotope geochemistry, the authors find that the banded skarn, which hosts the deposit, was precipitated from hydrothermal solutions in the form of exhalate sediment. Therefore, the banded skarn hosted copper deposit is a Sedex type deposit, with a series of stacked, conformable lenses underlain by at least one stringer zone. The deposit, intercalated at the contact of lower clastic rock and upper carbonate rock of Gajinxueshan Group, was formed in the Carboniferous ((296.1±7.0) Ma), contemporary to the host Gajinxueshan Group. The interpretation of the genesis of Yangla banded skarn hosted copper deposit is of fundamental exploration significance for the discovery of Sedex type copper deposit in the region.
基金jointly by the National Natural Science Foundation of China(41862007 and 41402072)Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(No.YNWR-QNBJ-2018-093)+2 种基金the Key Disciplines Construction of Kunming University of Science and Technology(No.14078384)the Analysis and Testing Foundation of Kunming University of Science and Technology(2017T20160006)We are grateful to Dr.Jianping Liu,Dr.Weikang Chen,and Dr.Shaoqing Liu(School of Geosciences and Info-physics,Central South University)for sulfides EPMA analyses:and Dr.Yuedong Liu,Dr.Cheng Luo.Dr.Xiaoqing Liu and Dr.Zaizao Li(Yunnan Diqin Mining Industry Group)for their field work.The authors would also like to thank anonymous reviewers for their useful comments and constructive reviews,which significantly improved the manuscript.
文摘The Yangla Cu deposit is the largest ore deposit in the Jinshajiang polymetallic metallogenic belt,northwest Yunnan,China.There is no consensus on the genesis of the ore deposit owing to the limited studies on the chemical compositions of sulfides.This study used an electron probe micro-analyzer to constrain the chemical compositions of pyrite,chalcopyrite,molybdenite,and sphalerite in the porphyry Cu ore of the Yangla Cu deposit and compared them with the chemical compositions of sulfides in the skarn Cu ore.The trace element contents and their occurrences were used to estimate the metallogenic temperature and infer the genesis of the Yangla deposit.The results show that the sulfides in the porphyry Cu ores have variations of ore element concentrations relative to their theoretical values.Pyrite is depleted in S but elevated in Fe;chalcopyrite is depleted in Cu,Fe,and S;and molybdenite and sphalerite are enriched in S whilst depleted in Mo and Zn.The concentrations of the main metallogenic elements Cu,Fe,Mo,Zn,and S in the porphyry are generally lower than those in skarn,suggesting that the porphyry ore was formed in a moderate to moderate-high temperature metallogenic environment.The formation time may also be slightly later than that of the skarn Cu ore.Elements such as As,Co,Cu.Pb,Zn,Mo,Cd,and Ni mainly exist as isomorphic replacements and mineral inclusions in the sulfides of both porphyry and skarn Cu ores.The trace element features of sulfides in the two ore bodies show that the Yangla Cu deposit may be a composite super imposed ore deposit,and让s formation has undergone the process of exhalative-sedimentary to skarnporphyry mineralization.
文摘The large-scale Yangla copper deposit, located in the central part of the Sanjiang Tethys polymetallic belt, is structurally controlled by the Jinsha River Fault and Yangla Fault. This deposit consists of seven ore blocks, including the Beiwu, Nilv, Jiangbian, Linong, Lunong, Tongjige and Jiaren. The Cu metal prospective reserves of the Yangla deposit are above 1 million tons. There are widely distributed Indosinian granodiorite and also many gabbro-diabase dikes and few quartz porphyries exposed in the Yangla ore district. The ore-hosting rocks are diopsode-garnet skarn, sericitie sandy slate and metamorphic quartz sandstone of the first member of the Devonian Linong Formation. Ore bodies occur as layered, stratoid, lenticular and veined shapes, and are strictly controlled by rocks, strata and structures.
基金financially supported by the China Geological Survey(No.12120113079400)
文摘The Yangla Copper Ore Field in Northwest Yunnan Province, China, is a large region of deposits dominated by copper-bearing skarns whose origin remains debatable despite numerous studies over the past two decades. We have investigated the geological and geochemical characteristics of the skarns using field and microscopic observations combined with chemical analyses. The results show that the skarns fall into two categories. The first category is metamorphic skarn, which constitute the majority （〉90%） of skarns in the deposit and is characterized by stratiform occurrences conformable to Devonian host strata, anhydrous mineral assemblages such as diopside＋hedenbergite＋quartz, widespread banded structure, fine-grainsize （〈200 μm） and preserved tuff-like textures. Whole-rock major element compositions, REE and trace-element compositions resemble those of the country rock slates or schists. The skarn layers occur at variable distances （0-2 000 m） from Indosinian plutonic bodies. Fracture-filling veins and/or alteration halos are scarce or absent in or near the skarn layers. This category of skarn probably formed by isochemical contact metamorphism of fine calcareous clastic sediments or impure carbonate rocks during emplacement of the plutonic bodies with no significant material migration by hydrothermal fluids involved during the process, in which case metallic enrichment of the skarn layers was present in the protolith of the skarn. The second category is metasomatic skarn with relatively coarse-grained textures （200-〉1 000 μm） and volatile-reach assemblages such as diopside＋tremolite＋scapolite at or near the igneous contact zones, which constitutes only a minor pro-portion of ore compared with metamorphic skarn. Taking into consideration diverse existing opinions about the genetic type of the deposit, we suggest that the geological and whole-rock geochemical characteristics of the skarus are consistent with a metamorphosed and metasomatized SEDEX （sedimentary exhalative deposit） type rather than a hydrothermal metasomatic skarn type.
基金This research was funded by the National Natural Science Foundation of China(No.41862007)the Key Disciplines Construction of Kunming University of Science and Technology(No.14078384)the Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWR-QNBJ-2018-093)。
文摘The Yangla Cu skarn deposit is located in the central part of the Jinshajiang Suture Zone,southwest China,with a total reserve of 150 Mt Cu@1.03%.The newly discovered antimony orebodies at the depth of Yangla are strictly controlled by the stratum,structure,and lithology,which are lenticular and vein-like within the marble fracture zone,which can provide a window into multistage miner-alization and ore genesis at Yangla.Mineralization can be divided into three types,Cu–Pb–Zn(skarn)pyrite,galena,and sphalerite,Cu(porphyry)chalcopyrite and pyrite,and Sb(hydrothermal)stibnite and pyrite.The mineral assem-blages were stibnite+pyrite+calcite+quartz±minor scheelite in antimony ores.This study presents quantitative measurements of the trace element compositions of pyrite and stibnite from the Yangla antimony ores.Analysis of pyrite with electron probe microanalysis(EPMA)showed enrichment in Co,Ni,Sb,As,and Mo,and deficit in its S and Fe contents when compared to the stoichiometric con-centrations of S and Fe in pyrite.The Sb-related pyrite may belong to sedimentary-reworked genesis and may be modi-fied by hydrothermalfluids,thereby presenting a certain dif-ference(i.e.,crystal morphology,texture,and chemical com-position)compared to the skarn and porphyry Cu-related pyrite in the Yangla Cu skarn deposit.Analysis of stibnite with EPMA and inductively coupled plasma-mass spectrom-etry showed enrichment in As,Pb,Sn,Pb,Cu,and Zn,and presented much higher Sb contents and slightly lower S con-tents when compared to the stoichiometric concentrations of Sb and S in stibnite.Statistical analysis of the stibnite trace elements showed correlations for the elemental pairs Cu–Pb,As–Sb,and Sn–Pb,and the coupled substitution equations Sb^(3+)↔Cu^(+)+Pb^(2+),Sb^(3+)↔As^(3+),and Sn^(2+)↔Pb^(2+)may be the major factors governed the incorporating Cu,Pb,As and Sn within the stibnite.Moreover,this study preliminary shows that the antimony mineralization may belong to a car-bonate replacement hydrothermal genesis at Yangla.
基金This work was jointly supported by key project of Chinese Academy of Sciences (KZ952-S1-407) state Key Project of China (G1999043208 and 1999043210) China Postdoctoral Science Foundation.
文摘Four layers of cherts were found for the first time in the Yangla copper deposit, western Yunnan Province. The cherts possessed the following geochemical characteristics: 1 Low TiO2 and Al2O3 contents, but high ore-forming element (e.g. Cu, Au, Ag) contents; 2 low total REE contents and clear negative Eu anomalies when normalized to chondrite similar to the REE contents and distribution patterns of associated massive sulfide ores; 3 silicon isotopic compositions of cherts in the Yangla deposit being the same as cherts and geyserite of hot-water sedimentary origin; 4 lead and sulfur isotopic compositions of cherts in the Yangla deposit being similar to those of the massive sulfide ores in the Yangla deposit; 5 Rb-Sr isochron age of cherts from the Yangla deposit being identical with that of host strata. Hence, we conclude that the cherts in the Yangla deposit are of hot-water sedimentary origin, which have a close relationship with the massive sulfide ores. The discovery of hydrothermal cherts from the Yangla copper deposit provides further evidence for the hydrothermal exhalative origin of the massive sulfide deposits.
