On the basis of mineral paragenesis and the chemistry and homogenization temperatures of fluid inclusions,the physicochemical parameters were calculated for the formation of the Dalingkou Ag-Pb-Zu deposit in Zhejiang....On the basis of mineral paragenesis and the chemistry and homogenization temperatures of fluid inclusions,the physicochemical parameters were calculated for the formation of the Dalingkou Ag-Pb-Zu deposit in Zhejiang.From the early to the late stage of mineralization the ore-forming temperature veriation was found to be 298.5 ℃→267.0℃→217.6℃→167.3℃,with a corresponding pH change of 3.0-5.8→6.1→6.7→5.0→7.3.The pressure changed from 403.8to 128.5atm,and logfS2-9.9→-11.2→<-15;logfO2<-44→-45.6--42.6→>-44.2;and logf CO2 around -1.55.In conjunction with geological observations.the deposit is considered to be of meso-epithermal origin,i.e.,it was formed after continental volcanic-subvolcanic activity.The major factors affecting ore precipitation are the decreasing temperature and the increasing pH of ore-forming solutions.展开更多
Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone,the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are...Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone,the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are representative Pb-Zn deposits of the Pb-Zn-Cu polymetallic mineralization belt in the northern part of the Nujiang-Lancangjiang-Jinshajiang area,which are in the front belt of the Yushu thrust nappe system.The formed environments of these two deposits are different from those of sediment-hosted base metal deposits elsewhere in the world.The authors hold that they were formed during the Indian-Asian continental collision and developed within the fold-thrust belt combined with thrust and strike-slip-related Cenozoic basins in the interior of the collisional zone.Studying on the metallogenic epochs of these two deposits is helpful to the understanding of ore-forming regularity of the regional Pb-Zn-Cu mineralization belt and also to the search for new deposits in this region.The age of the Dongmozhazhua deposit has been determined by the Rb-Sr isochron method for sphalerite residues,whereas the age of the Mohailaheng deposit has been determined by the Rb-Sr isochron method for sphalerite residues and the Sm-Nd isochron method for fluorite.The age of the Dongmozhazhua deposit is 35.0-±0.0 Ma （（87Sr/86Sr）0=0.708807） for sphalerite residues.The age of the Mohailaheng deposit is 32.2±0.4 Ma （（87Sr/86Sr）o=0.708514） for sphalerite residues and 31.8±0.3 Ma （（143Nd/144Nd）o=0.512362） for fluorite with an average of 32.0 Ma.Together with the regional geological setting during mineralization,a possible tectonic model for metallogeny of the Dongmozhazhua and Mohailaheng Pb-Zn deposits has been established.These two ages are close to the ages of the Pb-Zn deposits in the Lanping and Tuotuohe basins,indicating that it is possible that the narrow 1000-kilometer-long belt controlled by a thrust nappe system on the eastern and northern margins of the Tibetan plateau could be a giant Pb-Zn mineralized belt.展开更多
The extensive Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe–Chengxian ore cluster in West Qinling. The ore bodies are mainly hosted in the marble, dolomitic marble and biotite-calcite-quartz schi...The extensive Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe–Chengxian ore cluster in West Qinling. The ore bodies are mainly hosted in the marble, dolomitic marble and biotite-calcite-quartz schist of the Middle Devonian Anjiacha Formation, and are structurally controlled by the fault and anticline. The ore-forming process can be divided into three main stages, based on field geological features and mineral assemblages. The mineral assemblages of hydrothermal stage I are pale-yellow coarse grain, low Fe sphalerite, pyrite with pits, barite and biotite. The mineral assemblages of hydrothermal stage II are black-brown cryptocrystalline, high Fe shalerite, pyrite without pits, marcasite or arsenopyrite replace the pyrite with pits, K-feldspar. The features of hydrothermal stage III are calcite-quartz-sulfide vein cutting the laminated, banded ore body. Forty-two sulfur isotope analyses, twenty-five lead isotope analyses and nineteen carbon and oxygen isotope analyses were determined on sphalerite, pyrite, galena and calcite. The δ34 S values of stage I(20.3 to 29.0‰) are consistent with the δ34 S of sulfate(barite) in the stratum. Combined with geological feature, inclusion characteristics and EPMA data, we propose that TSR has played a key role in the formation of the sulfides in stage I. The δ34 S values of stage II sphalerite and pyrite(15.1 to 23.0‰) are between sulfides in the host rock, magmatic sulfur and the sulfate(barite) in the stratum. This result suggests that multiple S reservoirs were the sources for S2-in stage II. The δ34 S values of stage III(13.1 to 22‰) combined with the structure of the geological and mineral features suggest a magmatic hydrothermal origin of the mineralization. The lead isotope compositions of the sulfides have 206 Pb/204 Pb ranging from 17.9480 to 17.9782, 207 Pb/204 Pb ranging from 15.611 to 15.622, and 208 Pb/204 Pb ranging from 38.1368 to 38.1691 in the three ore-forming stages. The narrow and symmetric distributions of the lead isotope values reflect homogenization of granite and mantle sources before the Pb-Zn mineralization. The δ13 CPDB and δ18 OSMOW values of stage I range from-0.1 to 2.4‰ and from 18.8 to 21.7‰. The values and inclusion data indicate that the source of fluids in stage I was the dissolution of marine carbonate. The δ13 CPDB and δ18 OSMOW values of stage II range from-4 to 1‰ and from 12.3 to 20.3‰, suggesting multiple C-O reservoirs in the Changba deposit and the addition of mantle-source fluid to the system. The values in stage III are-3.1‰ and 19.7‰, respectively. We infer that the process of mineralization involved evaporitic salt and sedimentary organic-bearing units interacting through thermochemical sulfate reduction through the isotopic, mineralogy and inclusion evidences. Subsequently, the geology feature, mineral assemblages, EPMA data and isotopic values support the conclusion that the ore-forming hydrothermal fluids were mixed with magmatic hydrothermal fluids and forming the massive dark sphalerite, then yielding the calcite-quartz-sulfide vein ore type at the last stage. The genesis of this ore deposit was epigenetic rather than the previously-proposed sedimentary-exhalative(SEDEX) type.展开更多
In recent years big strides have been made in the exploration of ores in the central-south segment of the Da Hinggan Ling Range,though some debates still exist on the metallogenesis and sources of ore-forming material...In recent years big strides have been made in the exploration of ores in the central-south segment of the Da Hinggan Ling Range,though some debates still exist on the metallogenesis and sources of ore-forming materials.Pyrite and other sulfides in direct relation to the Pb-Zn-Ag ore deposits were chosen for the He and Ar isotopic analysis of ore-forming fluids,and the first He and Ar isotope data have been obtained from the study region.3He/4He ratios in 14 samples collected from 7 mining districts are 2.17×10-6-12.52×10-6,averaging 6.86×10-6 and their R/Ra ratios are 1.56-9.01 Ra,averaging 4.37 Ra.By projecting the data points onto the 3He-4He concentrations diagram,all the points fall near the mantle helium area.The calculated mantle-source helium ratios are within the range of 19.58%-76.96%,with an average of 49.52%.Argon isotopic characteristics are close to those of mantle source,indicating that the ore-forming material was transport upwards via the multi-stage evolution of mantle plume and concentrated as ores in the favorable loci of mantle branch structures.展开更多
The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle ...The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.展开更多
Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang （geographical coordinates of E78° 57＇ 54.30＂-78°59＇ 53.63＂, N34° 39＇ 27.50＂-34° 40＇ 57.21＂）. It be...Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang （geographical coordinates of E78° 57＇ 54.30＂-78°59＇ 53.63＂, N34° 39＇ 27.50＂-34° 40＇ 57.21＂）. It belongs to the West Kunlun orogenic belt on the northwest edge of the Qinghai-Tibet Plateau and is connected to the Sanjiang orogenic belt to the south （Spurlin et al., 2005）. In recent years, a series of Pb-Zn mineralized spots and deposits have been discovered in this area one after another, which is called the Huoshaoyun ore concentration area. Among them, the Sachakou Pb-Zn deposit has reserves up to140 Mt, which has reached a large scale. However, the study on the genesis of deposits in this area has only just begun. This work studied the genesis ofthis Pb-Zn deposit in order to provide new ideas for the genesis of regional deposits and regional prospecting.展开更多
The Lijiagou Pb-Zn deposit in Gansu Province is a syngenetic hydrothermal-depositonal and meta-morphosed hydrothermal weakly-reworked stratabound ore deposit. The metallogenic physicochemical condi-tions of the deposi...The Lijiagou Pb-Zn deposit in Gansu Province is a syngenetic hydrothermal-depositonal and meta-morphosed hydrothermal weakly-reworked stratabound ore deposit. The metallogenic physicochemical condi-tions of the deposit are thoroughly dealt with in this paper according to its different mineralization stages.Based on the systematic study of metallogenic material sources, it is considered that the ore-forming metals, oresulphur and water of mineralizing fluids are mainly derived from the basement, reduction sulphur of marinesulfate and infiltrating heated meteoric water and partially recharged sea water, respectively. Finally, themetallogenic model of this deposit is established.展开更多
文摘On the basis of mineral paragenesis and the chemistry and homogenization temperatures of fluid inclusions,the physicochemical parameters were calculated for the formation of the Dalingkou Ag-Pb-Zu deposit in Zhejiang.From the early to the late stage of mineralization the ore-forming temperature veriation was found to be 298.5 ℃→267.0℃→217.6℃→167.3℃,with a corresponding pH change of 3.0-5.8→6.1→6.7→5.0→7.3.The pressure changed from 403.8to 128.5atm,and logfS2-9.9→-11.2→<-15;logfO2<-44→-45.6--42.6→>-44.2;and logf CO2 around -1.55.In conjunction with geological observations.the deposit is considered to be of meso-epithermal origin,i.e.,it was formed after continental volcanic-subvolcanic activity.The major factors affecting ore precipitation are the decreasing temperature and the increasing pH of ore-forming solutions.
文摘Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu-Nujiang suture zone,the Dongmozhazhua and Mohailaheng Pb-Zn deposits in the Yushu area of Qinghai Province are representative Pb-Zn deposits of the Pb-Zn-Cu polymetallic mineralization belt in the northern part of the Nujiang-Lancangjiang-Jinshajiang area,which are in the front belt of the Yushu thrust nappe system.The formed environments of these two deposits are different from those of sediment-hosted base metal deposits elsewhere in the world.The authors hold that they were formed during the Indian-Asian continental collision and developed within the fold-thrust belt combined with thrust and strike-slip-related Cenozoic basins in the interior of the collisional zone.Studying on the metallogenic epochs of these two deposits is helpful to the understanding of ore-forming regularity of the regional Pb-Zn-Cu mineralization belt and also to the search for new deposits in this region.The age of the Dongmozhazhua deposit has been determined by the Rb-Sr isochron method for sphalerite residues,whereas the age of the Mohailaheng deposit has been determined by the Rb-Sr isochron method for sphalerite residues and the Sm-Nd isochron method for fluorite.The age of the Dongmozhazhua deposit is 35.0-±0.0 Ma （（87Sr/86Sr）0=0.708807） for sphalerite residues.The age of the Mohailaheng deposit is 32.2±0.4 Ma （（87Sr/86Sr）o=0.708514） for sphalerite residues and 31.8±0.3 Ma （（143Nd/144Nd）o=0.512362） for fluorite with an average of 32.0 Ma.Together with the regional geological setting during mineralization,a possible tectonic model for metallogeny of the Dongmozhazhua and Mohailaheng Pb-Zn deposits has been established.These two ages are close to the ages of the Pb-Zn deposits in the Lanping and Tuotuohe basins,indicating that it is possible that the narrow 1000-kilometer-long belt controlled by a thrust nappe system on the eastern and northern margins of the Tibetan plateau could be a giant Pb-Zn mineralized belt.
基金supported and funded by the Special Research Funding for Public Benefit sponsored by MLR(Grant No.200911007-21)the Fundamental Research Funds for the Central Public Welfare Research Institutes(Grant No.K1612 and K1607)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.300102279401)the Geological Survey Project(Grant No.N1916)and(Grant No.DD20190368)。
文摘The extensive Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe–Chengxian ore cluster in West Qinling. The ore bodies are mainly hosted in the marble, dolomitic marble and biotite-calcite-quartz schist of the Middle Devonian Anjiacha Formation, and are structurally controlled by the fault and anticline. The ore-forming process can be divided into three main stages, based on field geological features and mineral assemblages. The mineral assemblages of hydrothermal stage I are pale-yellow coarse grain, low Fe sphalerite, pyrite with pits, barite and biotite. The mineral assemblages of hydrothermal stage II are black-brown cryptocrystalline, high Fe shalerite, pyrite without pits, marcasite or arsenopyrite replace the pyrite with pits, K-feldspar. The features of hydrothermal stage III are calcite-quartz-sulfide vein cutting the laminated, banded ore body. Forty-two sulfur isotope analyses, twenty-five lead isotope analyses and nineteen carbon and oxygen isotope analyses were determined on sphalerite, pyrite, galena and calcite. The δ34 S values of stage I(20.3 to 29.0‰) are consistent with the δ34 S of sulfate(barite) in the stratum. Combined with geological feature, inclusion characteristics and EPMA data, we propose that TSR has played a key role in the formation of the sulfides in stage I. The δ34 S values of stage II sphalerite and pyrite(15.1 to 23.0‰) are between sulfides in the host rock, magmatic sulfur and the sulfate(barite) in the stratum. This result suggests that multiple S reservoirs were the sources for S2-in stage II. The δ34 S values of stage III(13.1 to 22‰) combined with the structure of the geological and mineral features suggest a magmatic hydrothermal origin of the mineralization. The lead isotope compositions of the sulfides have 206 Pb/204 Pb ranging from 17.9480 to 17.9782, 207 Pb/204 Pb ranging from 15.611 to 15.622, and 208 Pb/204 Pb ranging from 38.1368 to 38.1691 in the three ore-forming stages. The narrow and symmetric distributions of the lead isotope values reflect homogenization of granite and mantle sources before the Pb-Zn mineralization. The δ13 CPDB and δ18 OSMOW values of stage I range from-0.1 to 2.4‰ and from 18.8 to 21.7‰. The values and inclusion data indicate that the source of fluids in stage I was the dissolution of marine carbonate. The δ13 CPDB and δ18 OSMOW values of stage II range from-4 to 1‰ and from 12.3 to 20.3‰, suggesting multiple C-O reservoirs in the Changba deposit and the addition of mantle-source fluid to the system. The values in stage III are-3.1‰ and 19.7‰, respectively. We infer that the process of mineralization involved evaporitic salt and sedimentary organic-bearing units interacting through thermochemical sulfate reduction through the isotopic, mineralogy and inclusion evidences. Subsequently, the geology feature, mineral assemblages, EPMA data and isotopic values support the conclusion that the ore-forming hydrothermal fluids were mixed with magmatic hydrothermal fluids and forming the massive dark sphalerite, then yielding the calcite-quartz-sulfide vein ore type at the last stage. The genesis of this ore deposit was epigenetic rather than the previously-proposed sedimentary-exhalative(SEDEX) type.
文摘In recent years big strides have been made in the exploration of ores in the central-south segment of the Da Hinggan Ling Range,though some debates still exist on the metallogenesis and sources of ore-forming materials.Pyrite and other sulfides in direct relation to the Pb-Zn-Ag ore deposits were chosen for the He and Ar isotopic analysis of ore-forming fluids,and the first He and Ar isotope data have been obtained from the study region.3He/4He ratios in 14 samples collected from 7 mining districts are 2.17×10-6-12.52×10-6,averaging 6.86×10-6 and their R/Ra ratios are 1.56-9.01 Ra,averaging 4.37 Ra.By projecting the data points onto the 3He-4He concentrations diagram,all the points fall near the mantle helium area.The calculated mantle-source helium ratios are within the range of 19.58%-76.96%,with an average of 49.52%.Argon isotopic characteristics are close to those of mantle source,indicating that the ore-forming material was transport upwards via the multi-stage evolution of mantle plume and concentrated as ores in the favorable loci of mantle branch structures.
基金granted by the National Natural Science Foundation of China (Grant No. 41172047, 41272062)the Open Fund of the State Key Laboratory of Ore Deposit Geochemistry (Institute of Geochemistry, Chinese Academy of Sciences, Guiyang) (Grant No. 201308)
文摘The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.
基金the 8th Geological Brigade of Aksu,Xinjiang, the Institute of Geology of the Chinese Academy of Geological Sciencesthe Beijing Research Institute of Uranium Geology,CNNC
文摘Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang （geographical coordinates of E78° 57＇ 54.30＂-78°59＇ 53.63＂, N34° 39＇ 27.50＂-34° 40＇ 57.21＂）. It belongs to the West Kunlun orogenic belt on the northwest edge of the Qinghai-Tibet Plateau and is connected to the Sanjiang orogenic belt to the south （Spurlin et al., 2005）. In recent years, a series of Pb-Zn mineralized spots and deposits have been discovered in this area one after another, which is called the Huoshaoyun ore concentration area. Among them, the Sachakou Pb-Zn deposit has reserves up to140 Mt, which has reached a large scale. However, the study on the genesis of deposits in this area has only just begun. This work studied the genesis ofthis Pb-Zn deposit in order to provide new ideas for the genesis of regional deposits and regional prospecting.
文摘The Lijiagou Pb-Zn deposit in Gansu Province is a syngenetic hydrothermal-depositonal and meta-morphosed hydrothermal weakly-reworked stratabound ore deposit. The metallogenic physicochemical condi-tions of the deposit are thoroughly dealt with in this paper according to its different mineralization stages.Based on the systematic study of metallogenic material sources, it is considered that the ore-forming metals, oresulphur and water of mineralizing fluids are mainly derived from the basement, reduction sulphur of marinesulfate and infiltrating heated meteoric water and partially recharged sea water, respectively. Finally, themetallogenic model of this deposit is established.
