The Pulang porphyry copper deposit is located in the Zhongdian island arc belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the west...The Pulang porphyry copper deposit is located in the Zhongdian island arc belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the western margin of the Yangtze Platform. In the Yidun island arc, there occur well-known 'Gacun-style' massive sulfide deposits in the northern segment and plenty of porphyry copper deposits in the southern segment, of which the Pulang porphyry copper deposit is one of the representatives. Like the Yulong porphyry copper deposit, this porphyry copper deposit is also one of the most important porphyry copper deposits in the eastern Qinghai-Tibet Plateau. But it is different from other porphyry copper deposits in the eastern Qinghai-Tibet Plateau (e.g. those in the Gangdise porphyry copper belt and Yulong porphyry copper belt) in that it formed in the Indosinian period, while others in the Himalayan period. Because of its particularity among the porphyry copper deposits of China, this porphyry copper deposit is of great significance for the study of the basic geology and the evaluation and prediction of mineral resources in the Zhongdian island arc belt. However, no accurate chronological data are available for determining the timing of mineralization of the porphyry copper deposit. By field observation in the study area and Re-Os dating of molybdenite and K-Ar dating of hydrothermal minerals and whole rock from the typical geological bodies, the timing of mineralization of the porphyry copper deposit has systematically been determined for the first time. The K-Ar age for the hydrothermal mineralization of biotite-quartz monzonitic porphyry that has undergone patassic silicate (biotite and K-feldspar) alteration ranges from 235.4±2.4 to 221.5±2.0 Ma and the Re-Os age for molybdenite in the quartz-molybdenite stage is ~213±3.8 Ma. These data are very close to each other, suggesting that the ore-forming processes of the Pulang porphyry copper deposit was completed in the Indosinian. But the K-feldspar K-Ar age of the main orebodies suggests that the hydrothermal activity related to porphyry copper mineralization continued till ~182.5±1.8 Ma. This indicates that the lifespan of the hydrothermal system related to porphyry copper mineralization may have lasted at least 40 Ma. This hydrothermal thermal system with such a long lifespan may be one of the necessary conditions for forming large porphyry copper deposits with a high grade. No late Yanshanian and/or Himalayan magmatism (mineralization) were superimposed in the Pulang porphyry copper deposit.展开更多
The Jinman deposit is a Ag-bearing copper vein deposit located at the north marginof the Lanping-Simao back-arc basin in West Yunnan. Systematic studies of fluid inclusions andstable isotopes are presented in this pap...The Jinman deposit is a Ag-bearing copper vein deposit located at the north marginof the Lanping-Simao back-arc basin in West Yunnan. Systematic studies of fluid inclusions andstable isotopes are presented in this paper. The filling-replacement stage and the boiling-exhala-tive precipitation stage of mineralization took place at T1 = 140 - 280℃ and T2 = 94 - 204℃under pressure of (600 - 1200) ×105 Pa. The salinity of ore-forming solutions ranges from 5 wt%-20. 8 wt% (NaCl). Sulphide δ34S(CDT) values are in the rang of - 9.6‰ - + 11.03% witha range of 22. 66‰ showing an apparent "pagoda"-shaped distribution in histogram. Mean-while, the δ34S values of the various sulphides are consistent with the characters of isotope equi-librium fractionation, i. e., δ34SPy>δ34 SCp> δ34SBn. The TS/TOC ratios of the ores are widelyvariable between 0.16 and 5. 54 with no correlation of any kind can be established. Accirding to themodel of Ohmoto, the oxidation-reduction ratios of sulfur species in ore-forming solutions at the twomineralization stages were calculated to be R’1 = 2. 16×10(-17) and R’2 = 1. 55×104. δ13CCO2 (PDB)values obtained from fluid inclusions in calcite and quartz are between - 8.12‰ - - 3. 18‰, av-eraging - 5. 26‰, which are comparable with the isotopic composition of mantle-derived CO2.Inclusions in quartz yield δ13CCH4(PDB) between - 32. 11‰ and - 22. 04‰ (averaging- 26. 69‰),similar to that of methane in modern geothermal gases. For the ore-forming soutions, δ18OH2O(SMOW) values are between - 10. 57‰ and + 9. 77‰ and δDH2O(SMOW) are between - 51‰and - 135‰. Considering the effect of isotope exchange during waterrock reactions, most ofthe data are plotted along or close to the line defined by the reaction of meteoric water withclastic rocks, while a small part of the points fall near the reaction line of magmatic water withclastic rocks. In δ13C vs. δ18O diagram, the ore-forming soutions are plotted for the most partinto the mixing area between the meteoric fluid and the deep-seated fluid and partially on themixing line of P = 1.展开更多
The Pulang porphyry copper deposit,located in the Gezan tectonic-magmatic arc and south of the Yidun island arc,southwest of Sanjiang metallogenic belt in Yunnan province,is a super-large porphyry copper deposit.
On the basis of results of the studies of primary fluid inclusions, and the hydrogen and oxygen isotope data, the authors concluded that the early-stage ore-forming fluid from the Jinchangqing gold (copper) ore deposi...On the basis of results of the studies of primary fluid inclusions, and the hydrogen and oxygen isotope data, the authors concluded that the early-stage ore-forming fluid from the Jinchangqing gold (copper) ore deposit is a kind of sulfate type hot brine characterized by medium temperature and salinity, genetically related to the late-stage ore-forming fluid derived from an acidic and more reductive environment. However, the late-stage ore-forming fluid is a sort of low temperature and low salinity chloride-type hot brine which originated from a lower pressure, acidic and more oxidative environment. In general, the ore fluids were derived from the late-stage, or largely from the early-stage groundwater-derived meteoric water, which has a 12‰-17‰ heavier oxygen isotopic composition than the original rain water (δ{}+{18}O={-15.3‰}), and were formed during gold mineralization as a product of oxygen isotope exchange during the reaction between ore-forming fluid and wall rocks under a lower water/rock ratio condition.展开更多
The Xiaolongtan copper mining district is an important area in Dali, West Yunnan, where porphyry copper deposits occur, and copper orebodies are controlled by fault or contact zone structures between porphyry massifs ...The Xiaolongtan copper mining district is an important area in Dali, West Yunnan, where porphyry copper deposits occur, and copper orebodies are controlled by fault or contact zone structures between porphyry massifs and country rocks. Based on detailed field investigation and deep-going analysis, the authors systematically studied the tectonogeochemical features of this mining district, proposed the principle and foundation of metallogenic prognosis, and delineated the most potential mineralization target area.展开更多
The L ancangjiang tectonic zone in Western Yunnan is an important magmatic,meta- morphic and tectonic mobile zone of Southwestern China,whose geotectonic location is very unique. It is characterized by complex geologi...The L ancangjiang tectonic zone in Western Yunnan is an important magmatic,meta- morphic and tectonic mobile zone of Southwestern China,whose geotectonic location is very unique. It is characterized by complex geological structures,perfectly developed strata,fre- quent magmatic activities,various degrees of metamorphism,rich ore resources and lots of metal deposits,thus formed a centralized zone of mineralization and also constituted one of the importantmetallogenicbelts of noble and nonferrousmetal deposits.Thatiswhy the re- searching on geology for this zone is of great展开更多
The Machangqing complex is composed of early syenitic-monzonitic porphyry and late granite-porphyry. Geochemically, they are similar in major and trace element characteristics, and are characterized by relatively low ...The Machangqing complex is composed of early syenitic-monzonitic porphyry and late granite-porphyry. Geochemically, they are similar in major and trace element characteristics, and are characterized by relatively low TiO-2 （{<0.5}） and P-2O-5 （{<0.4}） and high alkali contents （K-2O+Na-2O > 8%）, with K-2O/Na-2O>1, the absence of significant Eu anomaly and pronounced negative anomalies in Nb, Ta, Ti, and enrichment in large-ion lithophile elements and light rare-earth elements. Zircon U-Th-Pb ELA-ICP-MS age determination of the Machangqing complex has revealed two discrete igneous events. The syenitic-monzonitic porphyry has an age of {35.6}± 3 Ma, MSWD={2.80}; the granite-porphyry, {35.0}±{0.2} Ma, MSWD={2.91}. The lifespan of magmatic activities of the Machangqing complex associated with Cu+Mo mineralization is about {0.6} Ma. The late-stage ore-bearing granite-porphyry has higher Ce4+/Ce3+ ratios （264） than the early-stage barren syenitic-monzonitic porphyry （102）. The increase of zircon Ce4+/Ce3+ ratios from the early-to late-stage porphyries indicates that the oxidation state of the magmas associated with copper mineralization increases with time.展开更多
The Emeishan continental flood basalt, which is widespread in Yunnan, Guizhou and Sichuan provinces of Southwest China, is the volcanic product of a Permian mantle plume, and native copper-chalcocite mineralization as...The Emeishan continental flood basalt, which is widespread in Yunnan, Guizhou and Sichuan provinces of Southwest China, is the volcanic product of a Permian mantle plume, and native copper-chalcocite mineralization associated with the basalt is very common in the border area of Yunnan and Guizhou provinces. The mineralization occurred in the tuff intercalation and terrestrial sedimentary rock intercalation which were formed during the main period of basalt eruption. The orebodies are controlled by the stratigraphic position and faults. Metal ore minerals in the ores are mainly native copper, chalcocite and tenorite, with small amounts of chalcopyrite, bomite, pyrite and malachite, and sometimes with large amounts of bitumen, carbon and plant debris. Several decades of ore deposits are distributed in the neighboring areas of the two provinces, while most of them are small-scale deposits or only ore occurrences. By comparing the lead isotopic composition of the ores with that of the wall-rocks, cover and basement rocks of various periods, the source of copper in this type of ore deposits was studied in this paper. The results showed that: (1) The Pb isotopic composition of the ores from ten deposits is absolutely different from that of siliceous-argillaceus rocks of the Upper Permian Xuanwei Formation, limestones of the Lower Permian Series and Carboniferous, Cambrian sandstone-shale and recta-sedimentary rock and dolomite from the upper part of the Meso-Proterozoic Kunyang Group. This indicates that ore lead was derived neither from the cover rock nor from the basement rocks; (2) Although the Neo-Proterozoic Siman dolomite and silicalite, and dolomite in the lower part of the Kunyang Group are similar in Pb isotopic composition to the ores, lead and copper contents in these rocks are very low and they have not made great contributions to copper mineralization; (3) The ores have the same Pb isotopic composition as the basalt, the latter being enriched in copper. These facts indicate that lead and copper were derived from the basalt. According to the regional geological data and the geological-geochemical characteristics of the ore deposits, it is suggested that ore-forming materials were leached out from the basalt. The thickness and buried depth of the basalt and regional tectonic dynamics can affect the formation of large-scale copper deposits. Therefore, exploration for this type of ore deposits should be conducted in the areas from western Yunnan to western Sichuan, where there are developed basalts of great thickness, with extensive tectonic movement and magmatic activity.展开更多
Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge por...Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.展开更多
基金the Projects of Land and Mineral Resources Survey of the Ministry of Land and Resources(No.200310200001-4)National Natural Science Foundation of China(No.40272046)National Basic Research Project of the Ministry of Scienceand Technology of China(No.2002CB412610).
文摘The Pulang porphyry copper deposit is located in the Zhongdian island arc belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the western margin of the Yangtze Platform. In the Yidun island arc, there occur well-known 'Gacun-style' massive sulfide deposits in the northern segment and plenty of porphyry copper deposits in the southern segment, of which the Pulang porphyry copper deposit is one of the representatives. Like the Yulong porphyry copper deposit, this porphyry copper deposit is also one of the most important porphyry copper deposits in the eastern Qinghai-Tibet Plateau. But it is different from other porphyry copper deposits in the eastern Qinghai-Tibet Plateau (e.g. those in the Gangdise porphyry copper belt and Yulong porphyry copper belt) in that it formed in the Indosinian period, while others in the Himalayan period. Because of its particularity among the porphyry copper deposits of China, this porphyry copper deposit is of great significance for the study of the basic geology and the evaluation and prediction of mineral resources in the Zhongdian island arc belt. However, no accurate chronological data are available for determining the timing of mineralization of the porphyry copper deposit. By field observation in the study area and Re-Os dating of molybdenite and K-Ar dating of hydrothermal minerals and whole rock from the typical geological bodies, the timing of mineralization of the porphyry copper deposit has systematically been determined for the first time. The K-Ar age for the hydrothermal mineralization of biotite-quartz monzonitic porphyry that has undergone patassic silicate (biotite and K-feldspar) alteration ranges from 235.4±2.4 to 221.5±2.0 Ma and the Re-Os age for molybdenite in the quartz-molybdenite stage is ~213±3.8 Ma. These data are very close to each other, suggesting that the ore-forming processes of the Pulang porphyry copper deposit was completed in the Indosinian. But the K-feldspar K-Ar age of the main orebodies suggests that the hydrothermal activity related to porphyry copper mineralization continued till ~182.5±1.8 Ma. This indicates that the lifespan of the hydrothermal system related to porphyry copper mineralization may have lasted at least 40 Ma. This hydrothermal thermal system with such a long lifespan may be one of the necessary conditions for forming large porphyry copper deposits with a high grade. No late Yanshanian and/or Himalayan magmatism (mineralization) were superimposed in the Pulang porphyry copper deposit.
文摘The Jinman deposit is a Ag-bearing copper vein deposit located at the north marginof the Lanping-Simao back-arc basin in West Yunnan. Systematic studies of fluid inclusions andstable isotopes are presented in this paper. The filling-replacement stage and the boiling-exhala-tive precipitation stage of mineralization took place at T1 = 140 - 280℃ and T2 = 94 - 204℃under pressure of (600 - 1200) ×105 Pa. The salinity of ore-forming solutions ranges from 5 wt%-20. 8 wt% (NaCl). Sulphide δ34S(CDT) values are in the rang of - 9.6‰ - + 11.03% witha range of 22. 66‰ showing an apparent "pagoda"-shaped distribution in histogram. Mean-while, the δ34S values of the various sulphides are consistent with the characters of isotope equi-librium fractionation, i. e., δ34SPy>δ34 SCp> δ34SBn. The TS/TOC ratios of the ores are widelyvariable between 0.16 and 5. 54 with no correlation of any kind can be established. Accirding to themodel of Ohmoto, the oxidation-reduction ratios of sulfur species in ore-forming solutions at the twomineralization stages were calculated to be R’1 = 2. 16×10(-17) and R’2 = 1. 55×104. δ13CCO2 (PDB)values obtained from fluid inclusions in calcite and quartz are between - 8.12‰ - - 3. 18‰, av-eraging - 5. 26‰, which are comparable with the isotopic composition of mantle-derived CO2.Inclusions in quartz yield δ13CCH4(PDB) between - 32. 11‰ and - 22. 04‰ (averaging- 26. 69‰),similar to that of methane in modern geothermal gases. For the ore-forming soutions, δ18OH2O(SMOW) values are between - 10. 57‰ and + 9. 77‰ and δDH2O(SMOW) are between - 51‰and - 135‰. Considering the effect of isotope exchange during waterrock reactions, most ofthe data are plotted along or close to the line defined by the reaction of meteoric water withclastic rocks, while a small part of the points fall near the reaction line of magmatic water withclastic rocks. In δ13C vs. δ18O diagram, the ore-forming soutions are plotted for the most partinto the mixing area between the meteoric fluid and the deep-seated fluid and partially on themixing line of P = 1.
基金granted by China State Mineral Resources Investigation Program (Grant No.12120114013701 and 1212011120608)
文摘The Pulang porphyry copper deposit,located in the Gezan tectonic-magmatic arc and south of the Yidun island arc,southwest of Sanjiang metallogenic belt in Yunnan province,is a super-large porphyry copper deposit.
基金Thisresearchprojectwasgrantedjointlybythe95’StateKeyScienceandTechnologyProjects(96 914 03 04),ResearchProjectsin95’KeyRegionsandZonessponsoredbytheoriginalNon ferrousMetalIndustry GeneralCompany(96 D 42),theStateKeyBasicResearch,Develop mentandPlanningProgram(G1999043208)andtheFoundationProjects ofYunnanProvincialEducationDepartment(0142104).
文摘On the basis of results of the studies of primary fluid inclusions, and the hydrogen and oxygen isotope data, the authors concluded that the early-stage ore-forming fluid from the Jinchangqing gold (copper) ore deposit is a kind of sulfate type hot brine characterized by medium temperature and salinity, genetically related to the late-stage ore-forming fluid derived from an acidic and more reductive environment. However, the late-stage ore-forming fluid is a sort of low temperature and low salinity chloride-type hot brine which originated from a lower pressure, acidic and more oxidative environment. In general, the ore fluids were derived from the late-stage, or largely from the early-stage groundwater-derived meteoric water, which has a 12‰-17‰ heavier oxygen isotopic composition than the original rain water (δ{}+{18}O={-15.3‰}), and were formed during gold mineralization as a product of oxygen isotope exchange during the reaction between ore-forming fluid and wall rocks under a lower water/rock ratio condition.
文摘The Xiaolongtan copper mining district is an important area in Dali, West Yunnan, where porphyry copper deposits occur, and copper orebodies are controlled by fault or contact zone structures between porphyry massifs and country rocks. Based on detailed field investigation and deep-going analysis, the authors systematically studied the tectonogeochemical features of this mining district, proposed the principle and foundation of metallogenic prognosis, and delineated the most potential mineralization target area.
文摘The L ancangjiang tectonic zone in Western Yunnan is an important magmatic,meta- morphic and tectonic mobile zone of Southwestern China,whose geotectonic location is very unique. It is characterized by complex geological structures,perfectly developed strata,fre- quent magmatic activities,various degrees of metamorphism,rich ore resources and lots of metal deposits,thus formed a centralized zone of mineralization and also constituted one of the importantmetallogenicbelts of noble and nonferrousmetal deposits.Thatiswhy the re- searching on geology for this zone is of great
文摘The Machangqing complex is composed of early syenitic-monzonitic porphyry and late granite-porphyry. Geochemically, they are similar in major and trace element characteristics, and are characterized by relatively low TiO-2 （{<0.5}） and P-2O-5 （{<0.4}） and high alkali contents （K-2O+Na-2O > 8%）, with K-2O/Na-2O>1, the absence of significant Eu anomaly and pronounced negative anomalies in Nb, Ta, Ti, and enrichment in large-ion lithophile elements and light rare-earth elements. Zircon U-Th-Pb ELA-ICP-MS age determination of the Machangqing complex has revealed two discrete igneous events. The syenitic-monzonitic porphyry has an age of {35.6}± 3 Ma, MSWD={2.80}; the granite-porphyry, {35.0}±{0.2} Ma, MSWD={2.91}. The lifespan of magmatic activities of the Machangqing complex associated with Cu+Mo mineralization is about {0.6} Ma. The late-stage ore-bearing granite-porphyry has higher Ce4+/Ce3+ ratios （264） than the early-stage barren syenitic-monzonitic porphyry （102）. The increase of zircon Ce4+/Ce3+ ratios from the early-to late-stage porphyries indicates that the oxidation state of the magmas associated with copper mineralization increases with time.
基金support of the Key Orientation Project (No. KZCX2-YW-111) of Chinese Academy of SciencesNational Basic Research Program of China (No. 2007CB411408)
文摘The Emeishan continental flood basalt, which is widespread in Yunnan, Guizhou and Sichuan provinces of Southwest China, is the volcanic product of a Permian mantle plume, and native copper-chalcocite mineralization associated with the basalt is very common in the border area of Yunnan and Guizhou provinces. The mineralization occurred in the tuff intercalation and terrestrial sedimentary rock intercalation which were formed during the main period of basalt eruption. The orebodies are controlled by the stratigraphic position and faults. Metal ore minerals in the ores are mainly native copper, chalcocite and tenorite, with small amounts of chalcopyrite, bomite, pyrite and malachite, and sometimes with large amounts of bitumen, carbon and plant debris. Several decades of ore deposits are distributed in the neighboring areas of the two provinces, while most of them are small-scale deposits or only ore occurrences. By comparing the lead isotopic composition of the ores with that of the wall-rocks, cover and basement rocks of various periods, the source of copper in this type of ore deposits was studied in this paper. The results showed that: (1) The Pb isotopic composition of the ores from ten deposits is absolutely different from that of siliceous-argillaceus rocks of the Upper Permian Xuanwei Formation, limestones of the Lower Permian Series and Carboniferous, Cambrian sandstone-shale and recta-sedimentary rock and dolomite from the upper part of the Meso-Proterozoic Kunyang Group. This indicates that ore lead was derived neither from the cover rock nor from the basement rocks; (2) Although the Neo-Proterozoic Siman dolomite and silicalite, and dolomite in the lower part of the Kunyang Group are similar in Pb isotopic composition to the ores, lead and copper contents in these rocks are very low and they have not made great contributions to copper mineralization; (3) The ores have the same Pb isotopic composition as the basalt, the latter being enriched in copper. These facts indicate that lead and copper were derived from the basalt. According to the regional geological data and the geological-geochemical characteristics of the ore deposits, it is suggested that ore-forming materials were leached out from the basalt. The thickness and buried depth of the basalt and regional tectonic dynamics can affect the formation of large-scale copper deposits. Therefore, exploration for this type of ore deposits should be conducted in the areas from western Yunnan to western Sichuan, where there are developed basalts of great thickness, with extensive tectonic movement and magmatic activity.
文摘Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.
