The world-class Huize Pb-Zn deposits of Yunnan province,in southwestern China,located in the center of the Sichuan-Yunnan-Guizhou Pb-Zn polymetallic metallogenic province,has Pb＋Zn reserves of more than 5 million ton...The world-class Huize Pb-Zn deposits of Yunnan province,in southwestern China,located in the center of the Sichuan-Yunnan-Guizhou Pb-Zn polymetallic metallogenic province,has Pb＋Zn reserves of more than 5 million tons at Pb＋Zn grade of higher than 25%and contains abundant associated metals,such as Ag,Ge,Cd,and Ga.The deposits are hosted in the Lower Carboniferous carbonate strata and the Permian Emeishan basalts which distributed in the northern and southwestern parts of the orefield.Calcite is the only gangue mineral in the primary ores of the deposits and can be classified into three types,namely lumpy,patch and vein calcites in accordance with their occurrence.There is not intercalated contact between calcite and ore minerals and among the three types of calcite,indicating that they are the same ore-forming age with different stages and its forming sequence is from lumpy to patch to vein calcites. This paper presents the rare earth element（REE） and C-O isotopic compositions of calcites in the Huize Pb-Zn deposits.From lumpy to patch to vein calcites,REE contents decrease as LREE/ HREE ratios increase.The chondrite-normalized REE patterns of the three types of calcites are characterized by LREE-rich shaped,in which the lumpy calcite shows（La）_N〈（Ce）_N〈（Pr）_N≈（Nd）_N with Eu/Eu~＊〈1,the patch calcite has（La）_N〈（Ce）_N〈（Pr）_N≈（Nd）_N with Eu/Eu~＊〉1,and the vein calcite displays（La）_N〉（Ce）_N〉（Pr）_N〉（Nd）_N with Eu/Eu~＊〉1.The REE geochemistry of the three types of calcite is different from those of the strata of various age and Permian Emeishan basalt exposed in the orefield.Theδ^（13） C_（PDb） andδ^（18）O_（Smow） values of the three types of calcites vary from-3.5‰to-2.1‰and 16.7‰to 18.6‰,respectively,falling within a small field between primary mantle and marine carbonate in theδ^（13）C_（PDb） vsδ^（18）O_（Smow） diagram. Various lines of evidence demonstrate that the three types of calcites in the deposits are produced from the same source with different stages.The ore-forming fluids of the deposits resulted from crustal -mantle mixing processes,in which the mantle-derived fluid components might be formed from degassing of mantle or/and magmatism of the Permian Emeishan basalts,and the crustal fluid was mainly provided by carbonate strata in the orefield.The ore-forming fluids in the deposits were homogenized before mineralization,and the ore-forming environment varied from relatively reducing to oxidizing.展开更多
The western margin of Yangtze Craton is known as a significant sediment-hosted base-metal aggregate cluster,especially for Pb-Zn deposits in China,e.g.Jinding,Daliangzi,Tianbaoshan, Kuangshanchang and Qinlinchang depo...The western margin of Yangtze Craton is known as a significant sediment-hosted base-metal aggregate cluster,especially for Pb-Zn deposits in China,e.g.Jinding,Daliangzi,Tianbaoshan, Kuangshanchang and Qinlinchang deposits.In comparison with the classic MVT deposits in the world, based on the basic geology of the sediment-hosted Pb-Zn deposits,this paper focuses on temporal-spatial distribution of this deposit to further discuss its large scale mineralization and tectonic evolution history.In the SW Sanjiang Thethys,Jinding deposit is typically thrust fault-controlled and hosted mainly in the sandstones and breccia-bearing sandstones,whereas MVT-type deposits are controlled by lithology and faulting/fracturing with a strong preference for carbonate-hosted rocks.Most importantly,Jinding Pb-Zn deposit differs from the other types of sediment-hosted Pb-Zn deposits in which it was formed in a strongly deformed foreland basin within a continental collision zone.In the Kangdian area,the sediment-hosted Pb-Zn deposits were formed in the extensional basin on the side of the continental orogenic belt along the Yangtze Craton.Compared with classic MVT deposits,the Pb-Zn deposits in the Kangdian area belong to MVT deposits.This paper is significant not only for interpretation of the genesis of sediment-hosted Pb-Zn deposits but also for exploiting large base metal deposits in large sedimentary target areas.展开更多
The Erlihe Pb-Zn deposit is an important mine of the Pb-Zn metallogenic zone in the South Qinling Orogen.It has been considered a sedimentary exhalative deposit in previous investigations because the ore body occurs c...The Erlihe Pb-Zn deposit is an important mine of the Pb-Zn metallogenic zone in the South Qinling Orogen.It has been considered a sedimentary exhalative deposit in previous investigations because the ore body occurs concordantly at the transitional location of an upright fold.Re and Os isotopic analyses for paragenetic pyrites with sphalerite and galena from the ore body have been used to determine the timing of mineralization and to trace the source of metallogenic materials.The Re-Os isotopic data of four pyrite samples construct an isochron,yielding a weighted average age of 226±17 Ma（mean square weighted deviation=1.7）,which is considered the main mineralization age.A dioritic porphyrite vein sample,showing weaker mineralization,was also dated using the SHRIMP zircon UPb isotopic method to constrain the youngest metallogenic age of the ore deposit,because it distributes along a group of tensional joints cutting not only the upright fold in the deposit field,but also the main ore bodies.The dioritic porphyrite sample yields a weighted mean ^（206）Pb/^（238）U age of 221±3 Ma,which is slightly younger than the Re-Os isotopic isochron age of the pyrites,considered as the upper age limit of the mineralization,namely the ending age of the mineralization.The Os isotopic compositions of sulfide minerals distribute within a range between Os isotopic compositions of the crust and the mantle, indicating that the ore deposit can be derived from magma-related fluid,and the metallogenic materials are most likely derived from the mixing source of the crust and the mantle.The Erlihe Pb-Zn deposit and associated dioritic porphyrite vein,important records of Qinling tectonic-magmatism-mineralization activities,were formed during the Triassic collisional orogeny processes.展开更多
The Tianqiao Pb-Zn ore deposit of Guizhou Province, China, is located in the mid-east of the Sichuan-Yunnan-Guizhou Pb-Zn-Ag multi-metallic mineralization area, which is representative of the Pb-Zn ore de-posits in th...The Tianqiao Pb-Zn ore deposit of Guizhou Province, China, is located in the mid-east of the Sichuan-Yunnan-Guizhou Pb-Zn-Ag multi-metallic mineralization area, which is representative of the Pb-Zn ore de-posits in this area. It consists of three main orebodies, whose Pb+Zn reserves are more than 0.2 million ton. This paper analyzes the sulfur isotopic composition of these orebodies. The data show that the ore minerals (galena, sphalerite, pyrite) in these orebodies are enriched in heavy sulfur, with δ34SV-CDT values varying between 8.35‰ and 14.44‰, i.e. the δ34SV-CDT values of pyrite are between 12.81‰ and 14.44‰, the mean value is 13.40‰; the δ34SV-CDT values of sphalerite are range from 10.87‰ to 14.00‰, the mean value is 12.53‰; the δ34SV-CDT values of galena are range from 8.35‰ to 9.83‰, the mean value is 8.84‰, and they have the feature of δ34Spyrite>δ34Ssphalerite>δ34Sgalena, which indicates the sulfur isotope in ore-forming fluids has attained equilibrium. The δ34S V-CDT values of the deposit are close to those of sulfates from carbonate strata of different ages in the ore-field (15‰), which suggests that the sulfur in the ore-forming fluids should be derived from the thermo-chemical sulfate reduction of sulfates from the sedimentary strata.展开更多
Analyses of fluid\|inclusion leachates from ore deposits show that Na/Br ratios are within the range of 75-358 and Cl/Br 67-394, respectively, and this variation trend coincides with the seawater evaporation trajector...Analyses of fluid\|inclusion leachates from ore deposits show that Na/Br ratios are within the range of 75-358 and Cl/Br 67-394, respectively, and this variation trend coincides with the seawater evaporation trajectory on the basis of the Na/Br and Cl/Br ratios. The average Cl/Br and Na/Br ratios of mineralizing fluids are 185 and 173 respectively, which are very close to the ratios (120 and 233) of the residual evaporated seawater past the point of halite precipitation. It is suggested that the original mineralizing brine was derived from highly evaporated seawater with a high salinity. However, the inclusion fluids have absolute Na values of \{69.9\}-\{2606.2\} mmol kg\+\{-1\} and Cl values of \{106.7\}-\{1995.5\} mmol kg\+\{-1\}. Most of the values are much less than those of seawater: Na, 485 mmol kg\+\{-1\} and Cl, 566 mmol kg\+\{-1\}, respectively; the salinity measured from fluid inclusions of the deposits ranges from \{2.47 wt%\} to \{15.78 wt%\} NaCl equiv. The mineralizing brine has been diluted. The \{δ\{\}\+\{18\}O\} and δD values of ore\|forming fluids vary from \{-8.21‰\} to \{9.51‰\} and from \{-40.3‰\} to \{-94.3‰\}, respectively. The δD values of meteoric water in this region varied from \{-80‰\} to \{-100‰\} during the Jurassic. This evidenced that the ore\|forming fluids are the mixture of seawater and meteoric water. Highly evaporated seawater was responsible for leaching and extracting Pb, Zn and Fe, and mixed with and diluted by descending meteoric water, which resulted in the formation of ores.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 Mayuan stratabound Pb-Zn deposit in Nanzheng,Shaanxi Province,is located in the northern margin of the Yangtze Plate,in the southern margin of the Beiba Arch.The orebodies are stratiform and hosted in breciated do...The Mayuan stratabound Pb-Zn deposit in Nanzheng,Shaanxi Province,is located in the northern margin of the Yangtze Plate,in the southern margin of the Beiba Arch.The orebodies are stratiform and hosted in breciated dolostone of the Sinian Dengying Formation.The ore minerals are primarily sphalerite and galena,and the gangue minerals comprise of dolomite,quartz,barite,calcite and solid bitumen.Fluid inclusions from ore-stage quartz and calcite have homogenization tempreatures from 98 to 337℃ and salinities from 7.7 wt%to 22.2 wt%（NaCl equiv.）.The vapor phase of the inclusions is mainly composed of CH_4 with minor CO_2 and H_2S.The δD_（fluid） values of fluid inclusions in quartz and calcite display a range from-68‰ to-113‰（SMOW）,and the δ^（18）O_（fluid）values calculated from δ^（18）O_（quartz） and δ^（18）O_（calcite） values range from 4.5‰ to 16.7‰（SMOW）.These data suggest that the ore-forming fluids may have been derived from evaporitic sea water that had reacted with organic matter.The δ^（13）C_（CH4） values of CH_4 in fluid inclusions range from-37.2‰ to-21.0‰（PDB）,suggesting that the CH_4 in the ore-forming fluids was mainly derived from organic matter.This,together with the abundance of solid bitumen in the ores,suggest that organic matter played an important role in mineralization,and that the thermochemical sulfate reduction（TSR） was the main mechanism of sulfide precipitation.The Mayuan Pb-Zn deposit is a carbonate-hosted epigenetic deposit that may be classified as a Mississippi Valley type（MVT） deposit.展开更多
The Huogeqi orefield located on the northern side of Mt. Langshan, Inner Mongolia occurs in the Middle Proterozoic Langshan Group metamorphic rocks, and the orebodies arc stratiform. In the past twenty years, many Chi...The Huogeqi orefield located on the northern side of Mt. Langshan, Inner Mongolia occurs in the Middle Proterozoic Langshan Group metamorphic rocks, and the orebodies arc stratiform. In the past twenty years, many Chinese geologists have conducted researches on the Huogeqi Cu-Pb-Zn deposit, but there has been still a controversy on its origin. Some advocate that the deposit is of sedimentary-metamorphic rcworking origin, some hold that it is of sea-floor SEDEX origin, and others have a preference for magmatic superimposition origin. The crux of the controversy is that there is no common understanding about the source of ore-forming materials. In this paper, the Pb isotopic compositions of regional Achaean-Early Proterozoic basement rocks, various types of sedimentary- metamorphic rocks and volcanic rocks in the mining district, Late Proterozoic and Hercynian magmatic rocks arc introduced and compared with the orc-lead composition, so as to constrain the source of the ore lead. The result indicates that （1） sulfides in the ores have homogeneous Pb isotopic compositions, showing a narrow variation range. Their ^206pb/^204pb ratios arc within a range of 17.027- 17.317; ^207Pb/^204pb ratios, 15.451-15.786 and ^208Pb/^204pb ratios, 36.747-37.669; （2） the Pb isotopic compositions of the regional Achaean-Early Proterozoic basement rocks arc characteristic of the old Pb isotopic composition at the early-stage evolution of the Earth, which varies over a wider range, reflecting significant differences in Pb isotopic compositions of the ores. All this indicates that the source of ore lead has no bearing on the basement rocks; （3） the sedimentary-metamorphic rocks in the mining district arc characterized by highly variable and more radiogenic Pb isotopic compositions and their Pb isotopic ratios arc obviously higher than those of ores, demonstrating that ore lead did not result from metamorphic rcworking of these rocks; （4） Pb isotopic compositions of Late Proterozoic diorite-gabbro and Hercynian granite are higher than those of ores. Meanwhile, the Pb isotopic compositions of sulfides in the small-sized strata-penetrating mineralized veinlets formed at later stages arc completely consistent with that of sulfides in stratiform-banded ores, suggesting that these veiniets arc the product of autochthonous rcworking of the stratiform-banded ores during the period of metamorphism and the late magmatic superimposition-mineralization can be excluded; （5） amphibolite, whose protolith is basic volcanic rocks, has the same Pb isotopic compositions as ores, implying that ore lead was derived probably from basic volcanism. So, the source of ore-forming materials for the Huogeqi deposit is like that of the volcanic massive sulfide （VMS） deposits. However, the orebodies do not occur directly within the volcanic rocks, and instead they overlie the volcanic rocks, showing some differences from those typical VMS-type deposits.展开更多
The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely devel...The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.展开更多
We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, a...We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration.展开更多
The Tianbaoshan Pb\|Zn deposit in Sichuan Province, exhibiting open\|space\|filling and/or replacement textures, occurs as being of vein style in the Sinian (Late Proterozoic) carbonate rocks, and is simple in ore com...The Tianbaoshan Pb\|Zn deposit in Sichuan Province, exhibiting open\|space\|filling and/or replacement textures, occurs as being of vein style in the Sinian (Late Proterozoic) carbonate rocks, and is simple in ore composition. A systematic study of lead isotope and rare\|earth elements reveals that the ore\|forming materials were derived from multiple sources. The ultimate source of the sulfur in all stages is seawater sulfate but the reducing mechanisms are different. The carbon was derived from marine carbonate and organic matter. The ore\|forming fluid, meteoric in origin, belongs to a Ca\+\{2+\}\|Mg\+\{2+\}\|Cl\+-\|HCO\+-\-3 type of weak acidic to alkalic solutions with a salinity of about 5 wt% NaCl. The ore was formed at the depth of about 1 km from 150 to 250℃ during the main stage of ore deposition. The heated meteoric water, after extracting ore materials from wall rocks, evolved into ore\|forming solution with a low salinity, in which metals were transported as chloride complexes such as PbCl, ZnCl and ZnCl. The metal\|bearing solution moved upward along deep faults to low\|pressure zones, where the metal ions reacted with reduced sulfur and were precipitated as sulfide minerals. The textures of the minerals were controlled by the rate at which the reduced sulfur was supplied.展开更多
Geological setting\;Jinding superlarge Pb\|Zn deposit lies in the Lanping basin between the Lancangjiang fracture zone and the Jinshajiang\|Ailaoshan fracture zone. The Lanping basin is a Meso\|Cenozoic rifting basin ...Geological setting\;Jinding superlarge Pb\|Zn deposit lies in the Lanping basin between the Lancangjiang fracture zone and the Jinshajiang\|Ailaoshan fracture zone. The Lanping basin is a Meso\|Cenozoic rifting basin whose basement consists of the Paleozoic strata. Mesozoic paralic and continental sediments with a thickness of about 20000m deposited in the basin. In the Paleocene, gypsum\|salt\|bearing strata with a thickness of more than 1000m accumulated. In the Cenozoic, collision of the Indian plate with the Eurasian plate resulted in strong folding and napping and subsequent extensions in the Oligocene and Pliocene. The extensions were responsible for alkaline magmatic intrusion in the centre and alkaline magmatic extrusion in the east.Faulting is well developed. N\|S\|trending Bijiang fault with a length of 120km links with the Jinshajiang fracture zone in the north and with the Lancangjiang fracture zone in the south, controlling on the Cenozoic Lanping rifting basin and acting as passage\|way for ore fluids.展开更多
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
The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less...The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion.展开更多
The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good corr...The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good correlation between Cd and Zn in the primary ore. With the oxidation and resolution of pyrite, sphalerite, sulfide, and etc., many secondary minerals, such as colloform sphalerite and smithsonite, were formed. The distribution of Cd is not symmetrical, and enrichment and dilution were observed in partial area of the oxidation zone in the deposit. Cd, except in external pore space or cracks of secondary minerals as independent minerals, such as greenockite, was mainly distributed in sphalerite as an isomorphic impurity in the secondary sphalerate and smithsonite in the oxidation zone. The research showed that Cd showed a very strong active transfer ability in the oxidation process, not only indicating that supergene leaching might be the main reason for Cd enrichment in some Pb-Zn deposits, but also reflecting that Cd was easily mobilizeed and transferred to pollute ore areas in the oxidation process. Furthermore, Cd in oxidation ore was more easily mobilized and transferred to induce bad hazards for ore areas with the effect from AMD which was produced from oxidation of sulfides.展开更多
The polymetallic(Pb,Zn,Cu,etc) ore belt on the southwestern margin of Tarim is one of the major regions with the greatest prospecting potential in Xinjiang.Reported in this paper are the lead isotope data for 66 sulfi...The polymetallic(Pb,Zn,Cu,etc) ore belt on the southwestern margin of Tarim is one of the major regions with the greatest prospecting potential in Xinjiang.Reported in this paper are the lead isotope data for 66 sulfide samples(including 50 galena samples,15 chalcopyrite samples and 1 pyrite sample) collected from such representative deposits as Tamu,Tiekelike,Kalangu,Abalieke,etc.in this ore belt.The Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb in the galena samples range from 17.931 to 18.176,15.609 to 15.818 and 38.197 to 38.944,with the average values of 18.017,15.684 and 38.462,respectively.Those in the chalcopyrite samples range from 17.926 to 18.144,15.598 to 15.628 and 38.171 to 38.583,with the average values of 18.020,15.606 and 38.262,respectively.The pyrite sample has the Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb to be 17.980,15.604 and 38.145,respectively.In combination with the previous Pb isotope data for sulfides,it is found that there is only a slight variation in the Pb isotopic composition of galena,chalcopyrite,sphalerite and pyrite in the ore belt.However,there is some difference in Pb isotopic characteristics between galena and chalcopyrite,especially the Pb isotopic composition of galena shows an obvious linear correlation with some other relevant parameters(e.g.β and γ).The comprehensive analysis suggested that lead in galena(maybe including sphalerite and pyrite) was derived principally from wall rocks and underlying basement,and that in chalcopyrite only originated from the basement.The single-stage model ages of these sulfides couldn't indicate the time limit of metallogenesis(Pb,Zn,Cu,etc.),and the positive linear correlations for the Pb isotopic composition of galena are of no single-stage and two-stage Pb-Pb isochron significance.Furthermore,there are significant differences in Pb isotopic composition characteristics between the genetic type of deposits in this polymetallic ore belt and the Mississippi Valley type(MVT).In addition,the authors also pointed out that there is a phenomenon of differentiation(not paragenesis) for lead and copper elements during the process of metallogenesis in this ore belt.展开更多
基金jointly by National Basic Research Program of China(973 Program) (2007CB411402)the Knowledge innovation project of Chinese Academy of Sciences(KZCX2-YW-Q04-05, KZCX2-YW-111-03)the National Natural Science Foundation of China(No.40573036).
文摘The world-class Huize Pb-Zn deposits of Yunnan province,in southwestern China,located in the center of the Sichuan-Yunnan-Guizhou Pb-Zn polymetallic metallogenic province,has Pb＋Zn reserves of more than 5 million tons at Pb＋Zn grade of higher than 25%and contains abundant associated metals,such as Ag,Ge,Cd,and Ga.The deposits are hosted in the Lower Carboniferous carbonate strata and the Permian Emeishan basalts which distributed in the northern and southwestern parts of the orefield.Calcite is the only gangue mineral in the primary ores of the deposits and can be classified into three types,namely lumpy,patch and vein calcites in accordance with their occurrence.There is not intercalated contact between calcite and ore minerals and among the three types of calcite,indicating that they are the same ore-forming age with different stages and its forming sequence is from lumpy to patch to vein calcites. This paper presents the rare earth element（REE） and C-O isotopic compositions of calcites in the Huize Pb-Zn deposits.From lumpy to patch to vein calcites,REE contents decrease as LREE/ HREE ratios increase.The chondrite-normalized REE patterns of the three types of calcites are characterized by LREE-rich shaped,in which the lumpy calcite shows（La）_N〈（Ce）_N〈（Pr）_N≈（Nd）_N with Eu/Eu~＊〈1,the patch calcite has（La）_N〈（Ce）_N〈（Pr）_N≈（Nd）_N with Eu/Eu~＊〉1,and the vein calcite displays（La）_N〉（Ce）_N〉（Pr）_N〉（Nd）_N with Eu/Eu~＊〉1.The REE geochemistry of the three types of calcite is different from those of the strata of various age and Permian Emeishan basalt exposed in the orefield.Theδ^（13） C_（PDb） andδ^（18）O_（Smow） values of the three types of calcites vary from-3.5‰to-2.1‰and 16.7‰to 18.6‰,respectively,falling within a small field between primary mantle and marine carbonate in theδ^（13）C_（PDb） vsδ^（18）O_（Smow） diagram. Various lines of evidence demonstrate that the three types of calcites in the deposits are produced from the same source with different stages.The ore-forming fluids of the deposits resulted from crustal -mantle mixing processes,in which the mantle-derived fluid components might be formed from degassing of mantle or/and magmatism of the Permian Emeishan basalts,and the crustal fluid was mainly provided by carbonate strata in the orefield.The ore-forming fluids in the deposits were homogenized before mineralization,and the ore-forming environment varied from relatively reducing to oxidizing.
基金supported by the National Basic Research Program(No.2009CB421008)the Fundamental Research Funds for the Central Universities (No.2010ZY02)+2 种基金China Postdoctoral Science Foundation (No.20090460400)Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT)the 111 Project(No.B07011)
文摘The western margin of Yangtze Craton is known as a significant sediment-hosted base-metal aggregate cluster,especially for Pb-Zn deposits in China,e.g.Jinding,Daliangzi,Tianbaoshan, Kuangshanchang and Qinlinchang deposits.In comparison with the classic MVT deposits in the world, based on the basic geology of the sediment-hosted Pb-Zn deposits,this paper focuses on temporal-spatial distribution of this deposit to further discuss its large scale mineralization and tectonic evolution history.In the SW Sanjiang Thethys,Jinding deposit is typically thrust fault-controlled and hosted mainly in the sandstones and breccia-bearing sandstones,whereas MVT-type deposits are controlled by lithology and faulting/fracturing with a strong preference for carbonate-hosted rocks.Most importantly,Jinding Pb-Zn deposit differs from the other types of sediment-hosted Pb-Zn deposits in which it was formed in a strongly deformed foreland basin within a continental collision zone.In the Kangdian area,the sediment-hosted Pb-Zn deposits were formed in the extensional basin on the side of the continental orogenic belt along the Yangtze Craton.Compared with classic MVT deposits,the Pb-Zn deposits in the Kangdian area belong to MVT deposits.This paper is significant not only for interpretation of the genesis of sediment-hosted Pb-Zn deposits but also for exploiting large base metal deposits in large sedimentary target areas.
基金supported by the National Scientific and Technological Support Program of China (grant no:2006BAB01A11)
文摘The Erlihe Pb-Zn deposit is an important mine of the Pb-Zn metallogenic zone in the South Qinling Orogen.It has been considered a sedimentary exhalative deposit in previous investigations because the ore body occurs concordantly at the transitional location of an upright fold.Re and Os isotopic analyses for paragenetic pyrites with sphalerite and galena from the ore body have been used to determine the timing of mineralization and to trace the source of metallogenic materials.The Re-Os isotopic data of four pyrite samples construct an isochron,yielding a weighted average age of 226±17 Ma（mean square weighted deviation=1.7）,which is considered the main mineralization age.A dioritic porphyrite vein sample,showing weaker mineralization,was also dated using the SHRIMP zircon UPb isotopic method to constrain the youngest metallogenic age of the ore deposit,because it distributes along a group of tensional joints cutting not only the upright fold in the deposit field,but also the main ore bodies.The dioritic porphyrite sample yields a weighted mean ^（206）Pb/^（238）U age of 221±3 Ma,which is slightly younger than the Re-Os isotopic isochron age of the pyrites,considered as the upper age limit of the mineralization,namely the ending age of the mineralization.The Os isotopic compositions of sulfide minerals distribute within a range between Os isotopic compositions of the crust and the mantle, indicating that the ore deposit can be derived from magma-related fluid,and the metallogenic materials are most likely derived from the mixing source of the crust and the mantle.The Erlihe Pb-Zn deposit and associated dioritic porphyrite vein,important records of Qinling tectonic-magmatism-mineralization activities,were formed during the Triassic collisional orogeny processes.
基金supported by the National Basic Research Program of China (No. 2007CB411402)the National Natural Science Foundation of China (Grant No. 40573036)
文摘The Tianqiao Pb-Zn ore deposit of Guizhou Province, China, is located in the mid-east of the Sichuan-Yunnan-Guizhou Pb-Zn-Ag multi-metallic mineralization area, which is representative of the Pb-Zn ore de-posits in this area. It consists of three main orebodies, whose Pb+Zn reserves are more than 0.2 million ton. This paper analyzes the sulfur isotopic composition of these orebodies. The data show that the ore minerals (galena, sphalerite, pyrite) in these orebodies are enriched in heavy sulfur, with δ34SV-CDT values varying between 8.35‰ and 14.44‰, i.e. the δ34SV-CDT values of pyrite are between 12.81‰ and 14.44‰, the mean value is 13.40‰; the δ34SV-CDT values of sphalerite are range from 10.87‰ to 14.00‰, the mean value is 12.53‰; the δ34SV-CDT values of galena are range from 8.35‰ to 9.83‰, the mean value is 8.84‰, and they have the feature of δ34Spyrite>δ34Ssphalerite>δ34Sgalena, which indicates the sulfur isotope in ore-forming fluids has attained equilibrium. The δ34S V-CDT values of the deposit are close to those of sulfates from carbonate strata of different ages in the ore-field (15‰), which suggests that the sulfur in the ore-forming fluids should be derived from the thermo-chemical sulfate reduction of sulfates from the sedimentary strata.
基金ThisresearchprojectwasfundedbytheNationalNaturalScienceFoundationofChina (No .4 0 1 72 0 39)
文摘Analyses of fluid\|inclusion leachates from ore deposits show that Na/Br ratios are within the range of 75-358 and Cl/Br 67-394, respectively, and this variation trend coincides with the seawater evaporation trajectory on the basis of the Na/Br and Cl/Br ratios. The average Cl/Br and Na/Br ratios of mineralizing fluids are 185 and 173 respectively, which are very close to the ratios (120 and 233) of the residual evaporated seawater past the point of halite precipitation. It is suggested that the original mineralizing brine was derived from highly evaporated seawater with a high salinity. However, the inclusion fluids have absolute Na values of \{69.9\}-\{2606.2\} mmol kg\+\{-1\} and Cl values of \{106.7\}-\{1995.5\} mmol kg\+\{-1\}. Most of the values are much less than those of seawater: Na, 485 mmol kg\+\{-1\} and Cl, 566 mmol kg\+\{-1\}, respectively; the salinity measured from fluid inclusions of the deposits ranges from \{2.47 wt%\} to \{15.78 wt%\} NaCl equiv. The mineralizing brine has been diluted. The \{δ\{\}\+\{18\}O\} and δD values of ore\|forming fluids vary from \{-8.21‰\} to \{9.51‰\} and from \{-40.3‰\} to \{-94.3‰\}, respectively. The δD values of meteoric water in this region varied from \{-80‰\} to \{-100‰\} during the Jurassic. This evidenced that the ore\|forming fluids are the mixture of seawater and meteoric water. Highly evaporated seawater was responsible for leaching and extracting Pb, Zn and Fe, and mixed with and diluted by descending meteoric water, which resulted in the formation of ores.
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granted by the China State Mineral Resources Investigation Program(Grant No. 1212011121117)the National Natural Science Foudation of China(Grant No.41102050)the Central University Fund(310827153407)
文摘The Mayuan stratabound Pb-Zn deposit in Nanzheng,Shaanxi Province,is located in the northern margin of the Yangtze Plate,in the southern margin of the Beiba Arch.The orebodies are stratiform and hosted in breciated dolostone of the Sinian Dengying Formation.The ore minerals are primarily sphalerite and galena,and the gangue minerals comprise of dolomite,quartz,barite,calcite and solid bitumen.Fluid inclusions from ore-stage quartz and calcite have homogenization tempreatures from 98 to 337℃ and salinities from 7.7 wt%to 22.2 wt%（NaCl equiv.）.The vapor phase of the inclusions is mainly composed of CH_4 with minor CO_2 and H_2S.The δD_（fluid） values of fluid inclusions in quartz and calcite display a range from-68‰ to-113‰（SMOW）,and the δ^（18）O_（fluid）values calculated from δ^（18）O_（quartz） and δ^（18）O_（calcite） values range from 4.5‰ to 16.7‰（SMOW）.These data suggest that the ore-forming fluids may have been derived from evaporitic sea water that had reacted with organic matter.The δ^（13）C_（CH4） values of CH_4 in fluid inclusions range from-37.2‰ to-21.0‰（PDB）,suggesting that the CH_4 in the ore-forming fluids was mainly derived from organic matter.This,together with the abundance of solid bitumen in the ores,suggest that organic matter played an important role in mineralization,and that the thermochemical sulfate reduction（TSR） was the main mechanism of sulfide precipitation.The Mayuan Pb-Zn deposit is a carbonate-hosted epigenetic deposit that may be classified as a Mississippi Valley type（MVT） deposit.
基金supported jointly by the Bureau of Resources and Environment,Chinese Academy of Sciences(KZCX3-SW-125)the National Natural Science Foundation of China(Grant No,40172037).
文摘The Huogeqi orefield located on the northern side of Mt. Langshan, Inner Mongolia occurs in the Middle Proterozoic Langshan Group metamorphic rocks, and the orebodies arc stratiform. In the past twenty years, many Chinese geologists have conducted researches on the Huogeqi Cu-Pb-Zn deposit, but there has been still a controversy on its origin. Some advocate that the deposit is of sedimentary-metamorphic rcworking origin, some hold that it is of sea-floor SEDEX origin, and others have a preference for magmatic superimposition origin. The crux of the controversy is that there is no common understanding about the source of ore-forming materials. In this paper, the Pb isotopic compositions of regional Achaean-Early Proterozoic basement rocks, various types of sedimentary- metamorphic rocks and volcanic rocks in the mining district, Late Proterozoic and Hercynian magmatic rocks arc introduced and compared with the orc-lead composition, so as to constrain the source of the ore lead. The result indicates that （1） sulfides in the ores have homogeneous Pb isotopic compositions, showing a narrow variation range. Their ^206pb/^204pb ratios arc within a range of 17.027- 17.317; ^207Pb/^204pb ratios, 15.451-15.786 and ^208Pb/^204pb ratios, 36.747-37.669; （2） the Pb isotopic compositions of the regional Achaean-Early Proterozoic basement rocks arc characteristic of the old Pb isotopic composition at the early-stage evolution of the Earth, which varies over a wider range, reflecting significant differences in Pb isotopic compositions of the ores. All this indicates that the source of ore lead has no bearing on the basement rocks; （3） the sedimentary-metamorphic rocks in the mining district arc characterized by highly variable and more radiogenic Pb isotopic compositions and their Pb isotopic ratios arc obviously higher than those of ores, demonstrating that ore lead did not result from metamorphic rcworking of these rocks; （4） Pb isotopic compositions of Late Proterozoic diorite-gabbro and Hercynian granite are higher than those of ores. Meanwhile, the Pb isotopic compositions of sulfides in the small-sized strata-penetrating mineralized veinlets formed at later stages arc completely consistent with that of sulfides in stratiform-banded ores, suggesting that these veiniets arc the product of autochthonous rcworking of the stratiform-banded ores during the period of metamorphism and the late magmatic superimposition-mineralization can be excluded; （5） amphibolite, whose protolith is basic volcanic rocks, has the same Pb isotopic compositions as ores, implying that ore lead was derived probably from basic volcanism. So, the source of ore-forming materials for the Huogeqi deposit is like that of the volcanic massive sulfide （VMS） deposits. However, the orebodies do not occur directly within the volcanic rocks, and instead they overlie the volcanic rocks, showing some differences from those typical VMS-type deposits.
基金funded by National Nature Science Foundation of China (41273050, 41320104004)National Key Technology R&D Program in the 11th Five year Plan of China (No.2006 BAB01A08)the Geological Survey Project of China (12120114010301, 1212011220908)
文摘The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.
基金granted by the China's National Mineral Resources Investigation Program (Grant No.1212011220598) the Inner Mongolia Mineral Survey Fund(Grant No.KD-05-09)
文摘We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration.
文摘The Tianbaoshan Pb\|Zn deposit in Sichuan Province, exhibiting open\|space\|filling and/or replacement textures, occurs as being of vein style in the Sinian (Late Proterozoic) carbonate rocks, and is simple in ore composition. A systematic study of lead isotope and rare\|earth elements reveals that the ore\|forming materials were derived from multiple sources. The ultimate source of the sulfur in all stages is seawater sulfate but the reducing mechanisms are different. The carbon was derived from marine carbonate and organic matter. The ore\|forming fluid, meteoric in origin, belongs to a Ca\+\{2+\}\|Mg\+\{2+\}\|Cl\+-\|HCO\+-\-3 type of weak acidic to alkalic solutions with a salinity of about 5 wt% NaCl. The ore was formed at the depth of about 1 km from 150 to 250℃ during the main stage of ore deposition. The heated meteoric water, after extracting ore materials from wall rocks, evolved into ore\|forming solution with a low salinity, in which metals were transported as chloride complexes such as PbCl, ZnCl and ZnCl. The metal\|bearing solution moved upward along deep faults to low\|pressure zones, where the metal ions reacted with reduced sulfur and were precipitated as sulfide minerals. The textures of the minerals were controlled by the rate at which the reduced sulfur was supplied.
基金theNationalClimbingProgram(95 Pre .393 1 2 )andMLMRStrategicKeyProgram (95 0 110 3)
文摘Geological setting\;Jinding superlarge Pb\|Zn deposit lies in the Lanping basin between the Lancangjiang fracture zone and the Jinshajiang\|Ailaoshan fracture zone. The Lanping basin is a Meso\|Cenozoic rifting basin whose basement consists of the Paleozoic strata. Mesozoic paralic and continental sediments with a thickness of about 20000m deposited in the basin. In the Paleocene, gypsum\|salt\|bearing strata with a thickness of more than 1000m accumulated. In the Cenozoic, collision of the Indian plate with the Eurasian plate resulted in strong folding and napping and subsequent extensions in the Oligocene and Pliocene. The extensions were responsible for alkaline magmatic intrusion in the centre and alkaline magmatic extrusion in the east.Faulting is well developed. N\|S\|trending Bijiang fault with a length of 120km links with the Jinshajiang fracture zone in the north and with the Lancangjiang fracture zone in the south, controlling on the Cenozoic Lanping rifting basin and acting as passage\|way for ore fluids.
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.
基金financially supported by the State Basic Research Plan(973 project)(No.2011CB403100)IGCP/SIDA-600 project
文摘The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe（LRM） and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral（gahnite） trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn（Au） minerals in the distal fault systems surrounding the causative intrusion.
基金supported by the National ‘973 Project’ (No. 2009CB421003)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No: KZCX2-YW-111-03, KZCX2-YW-136-2)the Foundation of State Key Lab. of Ore Deposit Geochemistry
文摘The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good correlation between Cd and Zn in the primary ore. With the oxidation and resolution of pyrite, sphalerite, sulfide, and etc., many secondary minerals, such as colloform sphalerite and smithsonite, were formed. The distribution of Cd is not symmetrical, and enrichment and dilution were observed in partial area of the oxidation zone in the deposit. Cd, except in external pore space or cracks of secondary minerals as independent minerals, such as greenockite, was mainly distributed in sphalerite as an isomorphic impurity in the secondary sphalerate and smithsonite in the oxidation zone. The research showed that Cd showed a very strong active transfer ability in the oxidation process, not only indicating that supergene leaching might be the main reason for Cd enrichment in some Pb-Zn deposits, but also reflecting that Cd was easily mobilizeed and transferred to pollute ore areas in the oxidation process. Furthermore, Cd in oxidation ore was more easily mobilized and transferred to induce bad hazards for ore areas with the effect from AMD which was produced from oxidation of sulfides.
基金supported jointly by the National Natural Science Foundation of China (No.40903021)the Funding Project for Western Doctors of "Light of Western China" under the Talents Cultivation Program sponsored by the Chinese Academy of Sciences+2 种基金the "Eleventh Five-Year Plan" Key Project of National Science and Technology Supporting Plan(2006BAB07B04-04)the Innovation Project of theChinese Academy of Sciences (KZCX2-YW-107-6)the Research Project of the State Key Laboratory of Ore Deposit Geochemistry
文摘The polymetallic(Pb,Zn,Cu,etc) ore belt on the southwestern margin of Tarim is one of the major regions with the greatest prospecting potential in Xinjiang.Reported in this paper are the lead isotope data for 66 sulfide samples(including 50 galena samples,15 chalcopyrite samples and 1 pyrite sample) collected from such representative deposits as Tamu,Tiekelike,Kalangu,Abalieke,etc.in this ore belt.The Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb in the galena samples range from 17.931 to 18.176,15.609 to 15.818 and 38.197 to 38.944,with the average values of 18.017,15.684 and 38.462,respectively.Those in the chalcopyrite samples range from 17.926 to 18.144,15.598 to 15.628 and 38.171 to 38.583,with the average values of 18.020,15.606 and 38.262,respectively.The pyrite sample has the Pb isotopic ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb to be 17.980,15.604 and 38.145,respectively.In combination with the previous Pb isotope data for sulfides,it is found that there is only a slight variation in the Pb isotopic composition of galena,chalcopyrite,sphalerite and pyrite in the ore belt.However,there is some difference in Pb isotopic characteristics between galena and chalcopyrite,especially the Pb isotopic composition of galena shows an obvious linear correlation with some other relevant parameters(e.g.β and γ).The comprehensive analysis suggested that lead in galena(maybe including sphalerite and pyrite) was derived principally from wall rocks and underlying basement,and that in chalcopyrite only originated from the basement.The single-stage model ages of these sulfides couldn't indicate the time limit of metallogenesis(Pb,Zn,Cu,etc.),and the positive linear correlations for the Pb isotopic composition of galena are of no single-stage and two-stage Pb-Pb isochron significance.Furthermore,there are significant differences in Pb isotopic composition characteristics between the genetic type of deposits in this polymetallic ore belt and the Mississippi Valley type(MVT).In addition,the authors also pointed out that there is a phenomenon of differentiation(not paragenesis) for lead and copper elements during the process of metallogenesis in this ore belt.
