The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb ...The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.展开更多
The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a ...The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD-1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.展开更多
High-pressure(HP)or ultrahigh-pressure(UHP)rutile-quartz veins that form at mantle depths due to fluid-rock interaction can be used to trace the properties and behavior of natural fluids in subduction zones.To explore...High-pressure(HP)or ultrahigh-pressure(UHP)rutile-quartz veins that form at mantle depths due to fluid-rock interaction can be used to trace the properties and behavior of natural fluids in subduction zones.To explore the fluid flow and the associated element mobility during deep subduction and exhumation of the continental crust,we investigated the major and trace elements of Ti-rich minerals.Additionally,U–Pb dating,trace element contents,and Lu–Hf isotopic composition of zircon grains in the UHP eclogite and associated rutile-quartz veins were examined in the North Qaidam UHP metamorphic belt,Yuka terrane.The zircon grains in the rutile-quartz veins have unzoned or weak oscillatory zonings,and show low Th/U ratios,steep chondrite-normalized patterns of heavy rare earth elements(HREEs),and insignificant negative Eu anomalies,indicating their growth in metamorphic fluids.These zircon grains formed in 4313 Ma,which is consistent with the 4322 Ma age of the host eclogite.As for the zircons in the rutile-quartz veins,they showed steep HREE patterns on one hand,and were different from the zircons present in the host eclogite on the other.This demonstrates that their formation might have been related to the breakdown of the early stage of garnet,which corresponds to the abundance of fluids during the early exhumation stage.The core-rim profile analyses of rutile recorded a two-stage rutile growth across a large rutile grain;the rutile core has higher Nb,Ta,W,and Zr contents and lower Nb/Ta ratios than the rim,indicating that the rutile domains grew in different metamorphic fluids from the core towards the rim.The significant enrichment of high field strength elements(HFSEs)in the rutile core suggests that the peak fluids have high solubility and transportation capacity of these HFSEs.Furthermore,variations in the Nb vs.Cr trends in rutile indicate a connection of rutile to mafic protolith.The zircon grains from both the rutile-quartz veins and the host eclogite have similar Hf isotopic compositions,indicating that the vein-forming fluids are internally derived from the host eclogite.These fluids accumulated in the subduction channel and were triggered by local dehydration of the deeply subducted eclogite during the early exhumation conditions.展开更多
The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are ...The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰ to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/39Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar /4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.展开更多
REE composition of the carbonates of the auriferous quartz carbonate veins(QCVs) of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized RE...REE composition of the carbonates of the auriferous quartz carbonate veins(QCVs) of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.展开更多
The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contac...The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contact zone of an alkaline intrusion which was intruded into Archean metamorphic rocks and was formed not later than the Hercynian peried. Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103 ±4Ma, indicating that the gold deposit was formed in the Yenshanian period. 87Sr/86Sr sourcetracing shows the ore-forming materials came dominantly from alkaline intrusions. These results, combined with other isotope and REE data, suggest that the Dengping gold deposit is not a traditional magmatic hydrothermal deposit, but a reworked hydrothermal deposit related to heated and evoved meteoric water.展开更多
Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and h...Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and high homogenization temperatures ranging from 150 to 200℃ and 175 to 250℃, respectively. The salinity of aqueous inclusions, based on ice melting, varies between \{6.1\} and 8 equiv. wt% NaCl. On the other hand, H\-2O-CO\-2 fluid inclusions include three phases. Their total homogenization temperatures range from 270 to 325℃, and their salinity, based on clathrate melting, ranges between \{0.8\} and \{3.8\} equiv. wt% NaCl. CO\-2 fluid inclusions homogenize to a liquid phase and exhibit a low density range from \{0.52\} to \{0.66\} g/cm\+3. The partial mixing of H\-2O-CO\-2 and salt H\-2O-NaCl fluid inclusions is the main source of fluids from which the other types of inclusions were derived. The gold-bearing quartz veins are believed to be of medium temperature hydrothermal convective origin.展开更多
High-purity quartz (HPQ), the prime source of silica, is increasingly considered a strategic mineral in the world market because it is the raw material for special applications in high-tech industries owing to its uni...High-purity quartz (HPQ), the prime source of silica, is increasingly considered a strategic mineral in the world market because it is the raw material for special applications in high-tech industries owing to its unique physical and chemical properties. The expected growth in demand for HPQ implies that more sources have to be found. This is the primary motivation for this study which targets the Supe area, SW Region of Cameroon. The structural occurrences of quartz veins were mapped and samples collected. The chemical nature and textural features of these samples were subsequently analyzed by X-ray tomography, scanning electron microscopy (SEM), and electron microprobe analysis (EMPA). Three deformation events, D<sub>1</sub> - D<sub>3</sub> are recorded. D<sub>1</sub> is marked by the development of the strong S<sub>1</sub> foliation defined by the gneissic layering and schistosity. D<sub>2</sub> is a NE-SW ductile to brittle sinistral shear that controlled the formation of tension gashes that served as subsequent pathways for quartz-rich hydrothermal fluids to circulate and eventually precipitate quartz. The presence of rutile, tourmaline, and mica inclusions in the Supe veins affects the purity of the quartz. However, quartz can be treated to improve its quality. Taking into consideration the nine determinant trace elements used to classify HPQ, three (Li, P, and B) are below detection limits, Al concentrations are within the HPQ, quartz market standard, and average natural abundance;Ti values are high above all three standards in all except one sample, while Na, Ca, K, and Fe values fluctuate, thus classifying one of the samples as high purity quartz and the others as low purity quartz. These veins define tension gashes which usually occur in an echelon arrangement covering a large surface area, suggesting that more of such veins probably exist in the Supe area. Consequently, the quality and potential quantity of HPQ veins in this area suggest a high potential for HPQ exploration in the region.展开更多
In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope ...In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.展开更多
In the syenitic pluton of Guider (593 ± 4 Ma) in the North-West Cameroon domain of Central African Fold Belt, mineralized N-S to NE-SW vertical or sub-vertical quartz and quartz feldspar veins has been recently i...In the syenitic pluton of Guider (593 ± 4 Ma) in the North-West Cameroon domain of Central African Fold Belt, mineralized N-S to NE-SW vertical or sub-vertical quartz and quartz feldspar veins has been recently identified. In this contribution, we present petrography and mineralogy of these veins, in order to constrain their genesis and emplacement mechanisms based on detailed field work, petrographic studies and chemical characterization of minerals by using an electron probe microanalyser (EPMA). Field observations and vein microstructures show that the emplacement of the veins has been controlled by the dextral N-S trending strike-slip shear zones related to the regional D2 deformation phase. The results of mineralogical analysis reveal the co-presence of silicates and metallic minerals that include magnetite, ilmenite, pyrite, bismuthite, galena (very rare) and sulphide complexes (BiPbS, BiAgPbS, FeBiPbCuS, BiFe(TeS), FeBiPbS, BiPbCuS). The gangue is represented by quartz (quartz 1, quartz 2 and quartz 3), feldspars, sericite, chlorite, yellowish brown clay minerals, and hematite. The textural relationships between sulphides, quartz and alteration products show that the mineralization is essentially syn- to late-D2 and suggest that syenitic country rock and dextral shear zones have played an important role in the metallogenesis of these veins. This mineralization shows characteristics for copper-bearing calc-alkaline deposits, but differs from these by its more extensive alteration and its abundance in hematite. Substitutions of Al(IV) by Si(IV) in sericite associated with the sulphide mineralization and cataclastic deformation suggest that the temperature of trapping of the fluids is between 230°C and 275°C.展开更多
Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated ...Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated basement and geosynclinal trough deposits. The Pan-African Belt in Nigeria forms part of the Benin-Nigeria (Dahomeyan) shield which is regarded as the southern prolongation of the circumcratonic Pan-African belt of the West African Craton. Structurally controlled, gold-bearing quartz veins were measured and studied in the area from an extensive geological ground investigation. Field and petrographical studies indicate that the Neoproterozoic rocks constitute gneisses, amphibolite schist, amphibolites and migmatites. The amphibolites are intruded by pegmatites. The associated quartz veins are generally concordant with the main N</span></span><span><span><span>-</span></span></span><span><span><span>S regional structural trend. The lithological and structural studies carried out in these areas have demonstrated the relationship between structures and mineralization and/or lithology. The main characteristics of the gold mineralization in the area appear to indicate hydrothermal mineralization in connection with shear zones. This study allows us to predict that quartz veins in the amphibolite can be mined at a profit and a detailed geochemical and resource valuation needs to be carried out for the Au and associated Galena and Ag mineralization to fully exploit their economic potential.展开更多
Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins exp...Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins experienced strong alteration characterized by a typical mesothermal hydrothermal altered mineral assemblage.The grade of gold is affected by the contents of sulphides,e.g.galena,pyrite and chalcopyrite.Results of minor elements analysis for the of gold-bearing quartz veins indicate higher contents of Au and high contents of Ag,Pb,Cu,Cd,W,and Mo.Abundant fluid inclusions were found in the gold-bearing quartz veins.Three types of fluid inclusions were identified:(1) aqueous inclusions;(2) CO 2-bearing inclusions;and(3) daughter crystal-bearing fluid inclusions.Homogenization temperatures ranged from 110 to 670℃ with low and high peaks appearing at 160 180℃ and 280 300℃,respectively.The salinity of aqueous inclusions varies between 1.8 wt% and 38.2 wt% NaCl.The homogenization temperature and salinity show a positive correlation.The H and O isotopes of fluid inclusions in the gold-bearing quartz veins indicate that magmatic solution and metamorphic hydrothermal solution,together with meteoric water,were involved in the formation of gold-bearing fluid.Mesozoic magma activities related to granite intrusions should be the main source of CO 2 fluid with higher temperature and salinity.展开更多
Dahu-Qinnan molybdenum deposit,located in the northern part of the Xiaoqinling gold province,belongs to the Xiaoqinling-Waifangshan sub-zone of the eastern Qinling Mo-W metallogenic belt,central China.Molybdenite mine...Dahu-Qinnan molybdenum deposit,located in the northern part of the Xiaoqinling gold province,belongs to the Xiaoqinling-Waifangshan sub-zone of the eastern Qinling Mo-W metallogenic belt,central China.Molybdenite mineralization is associated with Au-bearing quartz veins.This paper is based on field observations and PIMA analytical data on the occurrences,and details textures and alteration patterns of Mo-bearing quartz veins in Dahu-Qinnan region.The Mo-bearing quartz veins exhibit friable with cream colored,vuggy,infilling texture and brecciated texture.The breccia clasts within Mo-bearing quartz veins are dominated by gneissic rocks of the Taihua Supergroup,and Mesozoic porphyritic granite dyke with stockwork and disseminated molybdenite mineralization.The breccias are replaced by clay minerals.Alteration associated with molybdenite-bearing quartz veins is characterized by K-feldspar(only in the breccias),sericite,sillicification(residual silica),kaolinite,smectite and anhydrite.Molybdenite with other sulfide minerals infills fissures and pore spaces in the quartz veins.As the results of above,and according to the observed geological events in the area and taking into account the geological setting,molybdenite-bearing quartz veins are likely to have been affected by late acid leaching.The precursor porphyry Mo ore,associated with porphyry granite dyke formed probably at ca.245--211 Ma during the continent-continenl collision of Qinling orogeny.展开更多
The auriferous veins at Jinniushan occurs within the Jinniushan faulted zone in the Kunyushan Granite. Optical observation reveals that gold ore body formed during the main stage of hydrothermal activity. Detailed geo...The auriferous veins at Jinniushan occurs within the Jinniushan faulted zone in the Kunyushan Granite. Optical observation reveals that gold ore body formed during the main stage of hydrothermal activity. Detailed geothermometric studies of fluid inclusions from the veins show that the forming temperature ranges between 130℃ and 370℃ and the salinity is from 4.01 to 15.21 wvt percent NaCl. The ore-forming fluid is featured by low to moderate salinity, and low to moderate temperature. According to investigations of the values of vapor/liquid and temperatures of the ore-forming fluids, we propose that the boiling fluid inclusions exist in the main mineralization stages. Fluid boiling is suggested as a mechanism for the precipitation of gold from the hydrothermal fluid in the Jinniushan gold deposit.展开更多
Gold mineralization in Mintom area, south Cameroon was studied in a tropical forest setting using X-ray diffraction, inductively coupled plasma-atomic emission spectrometry (ICP/AES) and inductively coupled plasma-mas...Gold mineralization in Mintom area, south Cameroon was studied in a tropical forest setting using X-ray diffraction, inductively coupled plasma-atomic emission spectrometry (ICP/AES) and inductively coupled plasma-mass spectrometry (ICP/MS) respectively for the mineralogical and chemical data. The mineralization occurs in quartz veins in the archean Ntem complex of the vast Congo Craton in Central Africa. Gold distribution patterns were vertically studied in the different horizons of the weathering profile and in the different grain-size fractions of the materials sampled in the pit on down slope of the interfluve where the mineralization exists. The weathering profile consists of an upper, thin loose sandy-clayey horizon (P6) covered by a light humic horizon, a nodular horizon with lateritic nodules or blocks (P5), a gravel horizon (P4), a thin spotted horizon (P3) and a saprolite (P2) up to 1.4 m thick. The specific geochemical signature of the bedrock is not recognized in each horizon of the weathering profile. Some groups of elements, e.g., high SiO2 and low REE characterize quartz vein while Cr-Ni characterizes a basic rock like gabbro. The residual gold is concentrated at the base of weathering profile. Its concentration increases from the saprolite up to the gravel horizon and decreases in the surface horizons. However, the evolution of visible Au distribution is not the same for all grain-size fractions: 1) in the finest fraction, the Au content is only regular in spotted and gravel horizons;2) in the medium size fractions, the Au is in high content and greatly decreases from saprolite up to the spotted horizon and disappears in the upper horizons;3) in the coarsest fraction, Au content is found in the saprolite and the maximum Au content of the weathering profile is found in this layer just above the mineralized quartz vein. This observation shows that the Mintom residual gold comes from the quartz vein.展开更多
It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar B...It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar Basin. The results show that fluid inclusions in quartz veins are small(1~5 μm)monophase, two-phase(liquid+vapour)aqueous inclusions; the two-phase aqueous inclusions homogeniese to the liquid phase between 120~180℃, two dominant types for oil inclusions were determined in quartz veins:① the primary inclusions, almostly gas, measurement by Laser-Raman Spectroscopy show that both gas phase are enriched in CH4(94.50%~99.25%)and C6H6(0.75%~2.70%), under these conditions, inclusions may have come from juvenile fliud followingly the quartz veins formation. While the quartz veins exhibiting different striking luminescence has been proved by cathodoluminescence, it would be impossible to come from the deep magmas and strata. ② aqueous, liquid and two-phase(liquid+vapour)oil inclusions, belong to secondary hydrocarbon inclusions. The oil inclusions of this stage represent mainly the large scale of oil accumulation, located within the quartz microfracture.展开更多
There are few Au-Pb-Quartz vein type ore deposits in other countries except China. It might be related to the geohistory and geotectonic background. However, this kind of ore deposit has an important economical signif...There are few Au-Pb-Quartz vein type ore deposits in other countries except China. It might be related to the geohistory and geotectonic background. However, this kind of ore deposit has an important economical significance in China. Its formation is due to the dis-tinctive geological conditions of china. Wendong Au-Pb-Quartz type ore deposit including Wenyu and Dongchuang in Xiaoqinling gold field is the most typical. It is a polygenetic and compound ore deposit, Jintongcha and other deposits lying to the west of it in Xiaoqinling area are Au-Pb-Quartz vein type ore deposits. Others of this area lying to the east of Jintongcha are Au-Quartz vein type. This phenomenon stems from the zonnal distribution of minernal de-posits and the different development of the two major minernalzation stages. The results ob-tained from the fluid inclusion research have supported this inference.展开更多
文摘The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.
基金supported jointly by grants No K1 022K0901 from the Scientific Research Fund of the China Central Non-Commercial Institutegrant No 40772063 from the National Natural Science Foundation of Chinathe Programme of Excellent Young Scientists of the Ministry of Land and Resources and Geological Survey Program Grant 1212010561603-2 from the China Geological Survey
文摘The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD-1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.
基金funded by the Fundamental Research Funds for National Universities, China University of Geosciences (Wuhan) and China Geological Survey (Grant Nos. 12120113032800, 21201011000150004, DD20190069)
文摘High-pressure(HP)or ultrahigh-pressure(UHP)rutile-quartz veins that form at mantle depths due to fluid-rock interaction can be used to trace the properties and behavior of natural fluids in subduction zones.To explore the fluid flow and the associated element mobility during deep subduction and exhumation of the continental crust,we investigated the major and trace elements of Ti-rich minerals.Additionally,U–Pb dating,trace element contents,and Lu–Hf isotopic composition of zircon grains in the UHP eclogite and associated rutile-quartz veins were examined in the North Qaidam UHP metamorphic belt,Yuka terrane.The zircon grains in the rutile-quartz veins have unzoned or weak oscillatory zonings,and show low Th/U ratios,steep chondrite-normalized patterns of heavy rare earth elements(HREEs),and insignificant negative Eu anomalies,indicating their growth in metamorphic fluids.These zircon grains formed in 4313 Ma,which is consistent with the 4322 Ma age of the host eclogite.As for the zircons in the rutile-quartz veins,they showed steep HREE patterns on one hand,and were different from the zircons present in the host eclogite on the other.This demonstrates that their formation might have been related to the breakdown of the early stage of garnet,which corresponds to the abundance of fluids during the early exhumation stage.The core-rim profile analyses of rutile recorded a two-stage rutile growth across a large rutile grain;the rutile core has higher Nb,Ta,W,and Zr contents and lower Nb/Ta ratios than the rim,indicating that the rutile domains grew in different metamorphic fluids from the core towards the rim.The significant enrichment of high field strength elements(HFSEs)in the rutile core suggests that the peak fluids have high solubility and transportation capacity of these HFSEs.Furthermore,variations in the Nb vs.Cr trends in rutile indicate a connection of rutile to mafic protolith.The zircon grains from both the rutile-quartz veins and the host eclogite have similar Hf isotopic compositions,indicating that the vein-forming fluids are internally derived from the host eclogite.These fluids accumulated in the subduction channel and were triggered by local dehydration of the deeply subducted eclogite during the early exhumation conditions.
基金the Ministry of Science and Technology of China(grants G 2001CB 409807,G 1999043216).
文摘The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰ to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/39Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar /4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.
基金funding through Minor Research Project from Indian School of Mines,Dhanbad and SERC,Department of Science & Technology,New Delhi,India
文摘REE composition of the carbonates of the auriferous quartz carbonate veins(QCVs) of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.
文摘The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contact zone of an alkaline intrusion which was intruded into Archean metamorphic rocks and was formed not later than the Hercynian peried. Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103 ±4Ma, indicating that the gold deposit was formed in the Yenshanian period. 87Sr/86Sr sourcetracing shows the ore-forming materials came dominantly from alkaline intrusions. These results, combined with other isotope and REE data, suggest that the Dengping gold deposit is not a traditional magmatic hydrothermal deposit, but a reworked hydrothermal deposit related to heated and evoved meteoric water.
文摘Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and high homogenization temperatures ranging from 150 to 200℃ and 175 to 250℃, respectively. The salinity of aqueous inclusions, based on ice melting, varies between \{6.1\} and 8 equiv. wt% NaCl. On the other hand, H\-2O-CO\-2 fluid inclusions include three phases. Their total homogenization temperatures range from 270 to 325℃, and their salinity, based on clathrate melting, ranges between \{0.8\} and \{3.8\} equiv. wt% NaCl. CO\-2 fluid inclusions homogenize to a liquid phase and exhibit a low density range from \{0.52\} to \{0.66\} g/cm\+3. The partial mixing of H\-2O-CO\-2 and salt H\-2O-NaCl fluid inclusions is the main source of fluids from which the other types of inclusions were derived. The gold-bearing quartz veins are believed to be of medium temperature hydrothermal convective origin.
文摘High-purity quartz (HPQ), the prime source of silica, is increasingly considered a strategic mineral in the world market because it is the raw material for special applications in high-tech industries owing to its unique physical and chemical properties. The expected growth in demand for HPQ implies that more sources have to be found. This is the primary motivation for this study which targets the Supe area, SW Region of Cameroon. The structural occurrences of quartz veins were mapped and samples collected. The chemical nature and textural features of these samples were subsequently analyzed by X-ray tomography, scanning electron microscopy (SEM), and electron microprobe analysis (EMPA). Three deformation events, D<sub>1</sub> - D<sub>3</sub> are recorded. D<sub>1</sub> is marked by the development of the strong S<sub>1</sub> foliation defined by the gneissic layering and schistosity. D<sub>2</sub> is a NE-SW ductile to brittle sinistral shear that controlled the formation of tension gashes that served as subsequent pathways for quartz-rich hydrothermal fluids to circulate and eventually precipitate quartz. The presence of rutile, tourmaline, and mica inclusions in the Supe veins affects the purity of the quartz. However, quartz can be treated to improve its quality. Taking into consideration the nine determinant trace elements used to classify HPQ, three (Li, P, and B) are below detection limits, Al concentrations are within the HPQ, quartz market standard, and average natural abundance;Ti values are high above all three standards in all except one sample, while Na, Ca, K, and Fe values fluctuate, thus classifying one of the samples as high purity quartz and the others as low purity quartz. These veins define tension gashes which usually occur in an echelon arrangement covering a large surface area, suggesting that more of such veins probably exist in the Supe area. Consequently, the quality and potential quantity of HPQ veins in this area suggest a high potential for HPQ exploration in the region.
基金This research project was granted jointly by the State Key Program (95pre39)sponsored by the China National Science and Tech nology Departmentthe State Out standing Young Scientists Foundation (GrantNo .4 96 2 5 3 0 4 ) and the Open Lab.of Ore Depo
文摘In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.
文摘In the syenitic pluton of Guider (593 ± 4 Ma) in the North-West Cameroon domain of Central African Fold Belt, mineralized N-S to NE-SW vertical or sub-vertical quartz and quartz feldspar veins has been recently identified. In this contribution, we present petrography and mineralogy of these veins, in order to constrain their genesis and emplacement mechanisms based on detailed field work, petrographic studies and chemical characterization of minerals by using an electron probe microanalyser (EPMA). Field observations and vein microstructures show that the emplacement of the veins has been controlled by the dextral N-S trending strike-slip shear zones related to the regional D2 deformation phase. The results of mineralogical analysis reveal the co-presence of silicates and metallic minerals that include magnetite, ilmenite, pyrite, bismuthite, galena (very rare) and sulphide complexes (BiPbS, BiAgPbS, FeBiPbCuS, BiFe(TeS), FeBiPbS, BiPbCuS). The gangue is represented by quartz (quartz 1, quartz 2 and quartz 3), feldspars, sericite, chlorite, yellowish brown clay minerals, and hematite. The textural relationships between sulphides, quartz and alteration products show that the mineralization is essentially syn- to late-D2 and suggest that syenitic country rock and dextral shear zones have played an important role in the metallogenesis of these veins. This mineralization shows characteristics for copper-bearing calc-alkaline deposits, but differs from these by its more extensive alteration and its abundance in hematite. Substitutions of Al(IV) by Si(IV) in sericite associated with the sulphide mineralization and cataclastic deformation suggest that the temperature of trapping of the fluids is between 230°C and 275°C.
文摘Dikko area, Niger State, North Central Nigeria falls within the Pan-African thermo-tectonic event which occurred in Nigeria as in other parts of West Africa with widespread effect on the mineralization of rejuvenated basement and geosynclinal trough deposits. The Pan-African Belt in Nigeria forms part of the Benin-Nigeria (Dahomeyan) shield which is regarded as the southern prolongation of the circumcratonic Pan-African belt of the West African Craton. Structurally controlled, gold-bearing quartz veins were measured and studied in the area from an extensive geological ground investigation. Field and petrographical studies indicate that the Neoproterozoic rocks constitute gneisses, amphibolite schist, amphibolites and migmatites. The amphibolites are intruded by pegmatites. The associated quartz veins are generally concordant with the main N</span></span><span><span><span>-</span></span></span><span><span><span>S regional structural trend. The lithological and structural studies carried out in these areas have demonstrated the relationship between structures and mineralization and/or lithology. The main characteristics of the gold mineralization in the area appear to indicate hydrothermal mineralization in connection with shear zones. This study allows us to predict that quartz veins in the amphibolite can be mined at a profit and a detailed geochemical and resource valuation needs to be carried out for the Au and associated Galena and Ag mineralization to fully exploit their economic potential.
基金supported jointly by the CNSF (No. 41173055)the National Basic Research Program of China (No.2003CB214605)
文摘Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins experienced strong alteration characterized by a typical mesothermal hydrothermal altered mineral assemblage.The grade of gold is affected by the contents of sulphides,e.g.galena,pyrite and chalcopyrite.Results of minor elements analysis for the of gold-bearing quartz veins indicate higher contents of Au and high contents of Ag,Pb,Cu,Cd,W,and Mo.Abundant fluid inclusions were found in the gold-bearing quartz veins.Three types of fluid inclusions were identified:(1) aqueous inclusions;(2) CO 2-bearing inclusions;and(3) daughter crystal-bearing fluid inclusions.Homogenization temperatures ranged from 110 to 670℃ with low and high peaks appearing at 160 180℃ and 280 300℃,respectively.The salinity of aqueous inclusions varies between 1.8 wt% and 38.2 wt% NaCl.The homogenization temperature and salinity show a positive correlation.The H and O isotopes of fluid inclusions in the gold-bearing quartz veins indicate that magmatic solution and metamorphic hydrothermal solution,together with meteoric water,were involved in the formation of gold-bearing fluid.Mesozoic magma activities related to granite intrusions should be the main source of CO 2 fluid with higher temperature and salinity.
基金financial support of Jinyuan Mining Industry Co.,Ltd,Lingbao,Henan Province。
文摘Dahu-Qinnan molybdenum deposit,located in the northern part of the Xiaoqinling gold province,belongs to the Xiaoqinling-Waifangshan sub-zone of the eastern Qinling Mo-W metallogenic belt,central China.Molybdenite mineralization is associated with Au-bearing quartz veins.This paper is based on field observations and PIMA analytical data on the occurrences,and details textures and alteration patterns of Mo-bearing quartz veins in Dahu-Qinnan region.The Mo-bearing quartz veins exhibit friable with cream colored,vuggy,infilling texture and brecciated texture.The breccia clasts within Mo-bearing quartz veins are dominated by gneissic rocks of the Taihua Supergroup,and Mesozoic porphyritic granite dyke with stockwork and disseminated molybdenite mineralization.The breccias are replaced by clay minerals.Alteration associated with molybdenite-bearing quartz veins is characterized by K-feldspar(only in the breccias),sericite,sillicification(residual silica),kaolinite,smectite and anhydrite.Molybdenite with other sulfide minerals infills fissures and pore spaces in the quartz veins.As the results of above,and according to the observed geological events in the area and taking into account the geological setting,molybdenite-bearing quartz veins are likely to have been affected by late acid leaching.The precursor porphyry Mo ore,associated with porphyry granite dyke formed probably at ca.245--211 Ma during the continent-continenl collision of Qinling orogeny.
基金中国科学院知识创新工程项目,National Science and Technology Project
文摘The auriferous veins at Jinniushan occurs within the Jinniushan faulted zone in the Kunyushan Granite. Optical observation reveals that gold ore body formed during the main stage of hydrothermal activity. Detailed geothermometric studies of fluid inclusions from the veins show that the forming temperature ranges between 130℃ and 370℃ and the salinity is from 4.01 to 15.21 wvt percent NaCl. The ore-forming fluid is featured by low to moderate salinity, and low to moderate temperature. According to investigations of the values of vapor/liquid and temperatures of the ore-forming fluids, we propose that the boiling fluid inclusions exist in the main mineralization stages. Fluid boiling is suggested as a mechanism for the precipitation of gold from the hydrothermal fluid in the Jinniushan gold deposit.
文摘Gold mineralization in Mintom area, south Cameroon was studied in a tropical forest setting using X-ray diffraction, inductively coupled plasma-atomic emission spectrometry (ICP/AES) and inductively coupled plasma-mass spectrometry (ICP/MS) respectively for the mineralogical and chemical data. The mineralization occurs in quartz veins in the archean Ntem complex of the vast Congo Craton in Central Africa. Gold distribution patterns were vertically studied in the different horizons of the weathering profile and in the different grain-size fractions of the materials sampled in the pit on down slope of the interfluve where the mineralization exists. The weathering profile consists of an upper, thin loose sandy-clayey horizon (P6) covered by a light humic horizon, a nodular horizon with lateritic nodules or blocks (P5), a gravel horizon (P4), a thin spotted horizon (P3) and a saprolite (P2) up to 1.4 m thick. The specific geochemical signature of the bedrock is not recognized in each horizon of the weathering profile. Some groups of elements, e.g., high SiO2 and low REE characterize quartz vein while Cr-Ni characterizes a basic rock like gabbro. The residual gold is concentrated at the base of weathering profile. Its concentration increases from the saprolite up to the gravel horizon and decreases in the surface horizons. However, the evolution of visible Au distribution is not the same for all grain-size fractions: 1) in the finest fraction, the Au content is only regular in spotted and gravel horizons;2) in the medium size fractions, the Au is in high content and greatly decreases from saprolite up to the spotted horizon and disappears in the upper horizons;3) in the coarsest fraction, Au content is found in the saprolite and the maximum Au content of the weathering profile is found in this layer just above the mineralized quartz vein. This observation shows that the Mintom residual gold comes from the quartz vein.
基金Supported by the National Natural Science Foundation of China(Grant No. 40372060)
文摘It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spect-roscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar Basin. The results show that fluid inclusions in quartz veins are small(1~5 μm)monophase, two-phase(liquid+vapour)aqueous inclusions; the two-phase aqueous inclusions homogeniese to the liquid phase between 120~180℃, two dominant types for oil inclusions were determined in quartz veins:① the primary inclusions, almostly gas, measurement by Laser-Raman Spectroscopy show that both gas phase are enriched in CH4(94.50%~99.25%)and C6H6(0.75%~2.70%), under these conditions, inclusions may have come from juvenile fliud followingly the quartz veins formation. While the quartz veins exhibiting different striking luminescence has been proved by cathodoluminescence, it would be impossible to come from the deep magmas and strata. ② aqueous, liquid and two-phase(liquid+vapour)oil inclusions, belong to secondary hydrocarbon inclusions. The oil inclusions of this stage represent mainly the large scale of oil accumulation, located within the quartz microfracture.
文摘There are few Au-Pb-Quartz vein type ore deposits in other countries except China. It might be related to the geohistory and geotectonic background. However, this kind of ore deposit has an important economical significance in China. Its formation is due to the dis-tinctive geological conditions of china. Wendong Au-Pb-Quartz type ore deposit including Wenyu and Dongchuang in Xiaoqinling gold field is the most typical. It is a polygenetic and compound ore deposit, Jintongcha and other deposits lying to the west of it in Xiaoqinling area are Au-Pb-Quartz vein type ore deposits. Others of this area lying to the east of Jintongcha are Au-Quartz vein type. This phenomenon stems from the zonnal distribution of minernal de-posits and the different development of the two major minernalzation stages. The results ob-tained from the fluid inclusion research have supported this inference.