The Jiajika granitic-and pegmatite-type lithium deposit,which is in the Songpan-Garze Orogenic Belt in western Sichuan Province,China,is the largest in Asia.Previous studies have examined the geochemistry and mineralo...The Jiajika granitic-and pegmatite-type lithium deposit,which is in the Songpan-Garze Orogenic Belt in western Sichuan Province,China,is the largest in Asia.Previous studies have examined the geochemistry and mineralogy of pegmatites and their parental source rocks to determine the genesis of the deposit.However,the evolution of magmatic-hydrothermal fluids has received limited attention.We analyzed He–Ar–H–O isotopes to decipher the ore-fluid nature and identify the contribution of fluids to mineralization in the late stage of crystallization differentiation.In the Jiajika ore field,two-mica granites,pegmatites(including common pegmatites and spodumene pegmatites),metasandstones,and schists are the dominant rock types exposed.Common pegmatites derived from early differentiation of the two-mica granitic magmas before they evolved into spodumene pegmatites during the late stage of the magmatic evolution.Common pegmatites have~3He/~4He ratios that vary from 0.18 to 4.68 Ra(mean1.62 Ra),and their~(40)Ar/~(36)Ar ratios range from 426.70 to 1408.06(mean 761.81);spodumene pegmatites have~3He/~4He ratios that vary from 0.18 to 2.66 Ra(mean 0.87Ra)and their~(40)Ar/~(36)Ar ratios range from 402.13 to 1907.34(mean 801.65).These data indicate that the hydrothermal fluids were shown a mixture of crust-and mantle-derived materials,and the proportion of crustderived materials in spodumene pegmatites increases significantly in the late stage of the magmatic evolution.Theδ~(18)OH_(2)O–VSMOWvalues of common pegmatites range from 6.2‰to 10.9‰,with a mean value of 8.6‰,andδDV–SMOWvalues vary from-110‰to-72‰,with a mean o f-85‰.Theδ~(18)OH_(2)O–VSMOWvalues of spodumene pegmatites range from 5.3‰to 13.2‰,with a mean of 9.1‰,andδDV–SMOWvalues vary from-115‰to-77‰,with a mean of-91‰.These data suggest that the ore-forming fluids came from primary magmatic water gradually mixing with more meteoric water in the late stage of the magmatic evolution.Based on the He–Ar–H–O and other existing data,we propose that the oreforming metals are mainly derived from the upper continental crust with a minor contribution from the mantle,and the fluid exsolution and addition of meteoric water during the formation of pegmatite contributed to the formation of the Jiajika superlarge lithium deposit.展开更多
The Dachang superlarge Sn-polymetal deposit in Guangxi, China, is one of the largest tin deposit all over the world. However, this deposit has long been in debate as to its origin. One of the opinions is that the Dach...The Dachang superlarge Sn-polymetal deposit in Guangxi, China, is one of the largest tin deposit all over the world. However, this deposit has long been in debate as to its origin. One of the opinions is that the Dachang deposit was formed by replacement of hydrothermal solution originating from Yanshanian granites, and the other is that this deposit was formed by submarine exhalation in the Devonian. This paper presents some new isotopic geochronology data obtained with the 40Ar-39Ar method for quartz and sanidine from massive ore in the No. 91 and No. 100 orebodies. Analytic results show that the No. 91 orebody was formed at 94.52±0.33 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz) or 91.4±2.9 Ma (the plateau age obtained with the 40Ar-39Ar method for feldspar), while the No. 100 orebody was formed at 94.56±0.45 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz), suggesting that both the No. 91 and the No. 100 orebodies were formed at the Late Yanshanian instead of the Devonian. The No. 100 orebody might be formed by filling of ore materials into caves in Devonian reef limestone. Because the ore-bearing solution released its pressure and lowered its temperature suddenly in a cave environment, ore minerals were formed concentratedly while water and other materials such as CO2 evaporated quickly, resulting less alteration of host rocks.展开更多
Seventy-three large-superlarge deposits in China were formed in 4 metallogenic epochs, and located in 6 metallogenic domains. By combing their time-space distribution and the relevant data of crustal thickness, we dis...Seventy-three large-superlarge deposits in China were formed in 4 metallogenic epochs, and located in 6 metallogenic domains. By combing their time-space distribution and the relevant data of crustal thickness, we discuss the control conditions of deep tectonics on superlarge deposits. The various spatial variation of the crustal thickness where deposits locate is closely related to their different tectonic setting. The crustal thickness of the region where deposits are in the Precatnbrian metallogenic epoch is 37.1 km and shows double-peak distribution, which is related to the different tectonic-mineralization processes in the Tarim-North China and Yangtze metallogenic domains. The crustal thickness of the region where deposits are in the Paleoproterozoic metallogenic epoch is 43.4 km and shows normal distribution, which is the result of 'pure' mineralization setting. The crustal thickness of the region where deposits are in the Late Palaeozoic-Early Mesozoic metallogenic epoch is about 41.2 km and shows multi-peak distribution, which can be related with dispersing distribution in the metallogenic domain of these superlarge deposits. The crustal thickness of the region where deposits are in the post-Indosinian metallogenic epoch is 37.3 km, and shows skew distribution, which resulted from different tectonic settings in eastern and western China.展开更多
The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements ...The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements and huminite reflectance. It is concluded that the source of Lincang superlarge deposit is mainly the muscovite granite in the west edge of the basin. During sedimentation, Ge (germanium) was leached out and entered the basin. Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes: peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO 2- 4 was reduced by coal organic matter. Pyrite and calcite formed. Hydrothermal process did not contribute significantly to mineralization.展开更多
Based on the data base of 1285 mineral deposits of 22 commodities in 121 countries of 6 continents of the world, the authors use the linear trend analysis for their reserves to determine the cut-off limited order of r...Based on the data base of 1285 mineral deposits of 22 commodities in 121 countries of 6 continents of the world, the authors use the linear trend analysis for their reserves to determine the cut-off limited order of reserves to select 36 exceptional superlarge (as peak mineral), 95 superlarge and 314 large deposits as new recognized intellect for their quantitative change. We have projected above 445 large-superlarge deposits on (1:5 M) global tectonic background map and divided 4 metallogenic domains, 21 metallogenic belts. Global metallogeny of large-superlarge deposits are: unity by endogenic, exogenic metamorphic and epigenetic in origin; speciality in different metallogenic domains and belts; preferentiality to ore-forming elements of Cu, Au, Fe, Ag, Cr, Mn, Zn, Pb, Sb, Hg, to continental margins or plate convergent belts, to Intra-continental tectono-magmatic complex belts and Large ductile shear zones; abnormality by the global oxyatmversion (excess oxygen atmospheric event) in Archean, redoxyatmversion (lack oxygen atmospheric event) in Proterozoic-Paleozoic, and tectonosphere thermal erosion (great amount of tectonic magmatic event) in Mesozoic-Cenozoic.展开更多
Objective The Mengshan area of the Xinyu City, Jiangxi Province is an important wollastonite production base in China. As early as the 90s of the 20th century, more than ten medium to small-sized wollastonite deposi...Objective The Mengshan area of the Xinyu City, Jiangxi Province is an important wollastonite production base in China. As early as the 90s of the 20th century, more than ten medium to small-sized wollastonite deposits, such as the Yueguangshan and Caofangmiao Deposits were discovered in the outer contact zone of the Mengshan rock mass. After that, no more progress was achieved in wollastonite prospection. In 2016, the project funded by the Geological Prospecting Fund of Jiangxi Province made significant breakthroughs in the "General Survey of the Shizhushan Wollastonite Ore in the Yushui District and Zhangmuqiao Wollastonite Ore in Shanggao County, Xinyu City, Jiangxi Province" in the Mengshan area. The new discovered Shizhushan Wollastonite Deposit has a scale of 50 million tons and its resources scale far exceeds that of the Seeleys Bay Wollastonite Deposit discovered in Canada.展开更多
Based on the study of tens of geophysical profiles (seismic, geothermal flow and magnetotelluric sounding profiles) and 3-D shear wave velocity structures of the Chinese continent and its neighbouring regions, this pa...Based on the study of tens of geophysical profiles (seismic, geothermal flow and magnetotelluric sounding profiles) and 3-D shear wave velocity structures of the Chinese continent and its neighbouring regions, this paper describes the 3-D crustal and upper mantle structures and discusses briefly the deep geophysical background of superlarge ore deposits in the Chinese continent. Superlarge deposits are usually very few in number, but they are distributed still in certain forms such as “point”, “zone” and “area”. Most of the large-, medium- and small-sized deposits occur near the margins of different tectonic units; while the superlarge endogenic polymetallic deposits occur mostly in thinned mantle lithosphere, uplifts of the asthenosphere (vertical low-velocity zones) and the transformation zones of lateral inhomogeneity (weak zones) in the upper mantle. The superlarge endogenic polymetallic deposits are almost unevenly distributed in three major ore zones in China, corresponding to the boundaries of inhomogeneous regions in the asthenosphere.展开更多
Interest in the ore\|forming histories of basins has grown rapid since 1960 and is now intensive. The main reason behind the acceleration is the increasing awareness that the natural processes responsible for generati...Interest in the ore\|forming histories of basins has grown rapid since 1960 and is now intensive. The main reason behind the acceleration is the increasing awareness that the natural processes responsible for generating metal deposits in the sedimentary basin from the source rocks of the beneath the basin and intensively hydrothermal activity in the basin. Observations made in different continental margin basin systems and superlarge deposits in Chinese Yunnan\|Guizhou\|Guangxi Province on the eastern margin of the Qingzang (Himalaya—Karakoram—Tibet) were investigated in terms of geodynamics of basin formation. Geotectonically, the area is situated in the conjoint between the Tethys—Himalaya and the Marginal\|Pacific tectonic domain, characterized by very complex geological structure, typical basin\|mountain tectonics, abundant Superlarge deposits.展开更多
The superlarge Jinchang gold deposit is located in the joint area between the Taipingling uplift and the Laoheishan depression of the Xingkai Block in both eastern Jilin and eastern Heilongjiang Province. Wall rocks o...The superlarge Jinchang gold deposit is located in the joint area between the Taipingling uplift and the Laoheishan depression of the Xingkai Block in both eastern Jilin and eastern Heilongjiang Province. Wall rocks of the gold deposits are the Neoproterozoic Huangsong Group of metamorphic rocks. Yanshanian magmatism in this region can be divided into 5 phases, the diorite, the graphic granite, the granite, the granite porphyry and the diorite porphyrite, which resulted in the magmatic domes and cryptoexplosive breecia chimney followed by large-scale hydrothermal alteration. Gold mineralization is closely related to the fourth and fifth phase of magmatism. According to the occurrences, gold ores can be subdivided into auriferous pyritized quartz vein, auriferous quartz-pyrite vein, auriferous polymetailic sulfide quartz vein and auriferous pyritized calcite vein. The ages of the gold deposit are ranging from 122.53 to 119.40 Ma. The ore bodies were controlled by a uniform tectono-magmatic hydrothermal alteration system that the ore-forming materials were deep derived from and the ore-forming fluids were dominated by magmatic waters with addition of some atmospheric water in the later phase of mineralization. Gold mineralization took place in an environment of medium to high temperatures and medium pressures. Ore-forming fluids were the K^+-Na^+-Ca^2+-Cl^--SO4^2- type and characterized by medium salinity or a slightly higher, weak alkaline and weak reductive. Au in the ore-forming fluids was transported as complexes of [Au (HS)2]^-, [AuCl2]^-, [Au(CO2)]^- and [Au(HCO3)2]^-. Along with the decline of temperatures and pressures, the ore-forming fluids varied from acidic to weak acidic and then to weak alkaline, which resulted in the dissociation of the complex and finally the precipitation of the gold.展开更多
The greenstone belt and metamorphosed microclastic rock\|type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies. Sedimentation, regional metamorphism and mineralization contr...The greenstone belt and metamorphosed microclastic rock\|type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies. Sedimentation, regional metamorphism and mineralization contributed a lot to the formation of the deposits, so did remelting magmatic process to some deposits, but the deposits were finally formed by reworking processes. The key factor leading to the formation of superlarge gold deposits is the reworking intensity, which for superlarge gold deposits is reflected by the large\|scale reworked source rocks and even ore materials of various sources, strongly oxidized ore\|forming fluids with a long and repeated active history and stable geothermal heat current. The factor which decides the reworking intensity is the network consisting of structures of different classes.展开更多
The superlarge continental volcanic rock\|type uranium deposits, which were discovered abroad long ago, have not yet been reported up to now in China. This is an important problem that needs to be urgently solved by u...The superlarge continental volcanic rock\|type uranium deposits, which were discovered abroad long ago, have not yet been reported up to now in China. This is an important problem that needs to be urgently solved by uranium geologists at present. In this paper, on the basis of analyzing the metallogenic settings and geological conditions of the superlarge continental volcanic rock\|type uranium deposits discovered in the world along with the metallogenic characteristics of those of the same type in China, the space\|time distribution patterns of continental volcanics and the metallogenic potential of main tectono\|volcanic belts in China are discussed, and a synthetic conclusion has been drawn that there is a possibility to discover the superlarge continental volcanic rock\|type uranium deposits in China. Moreover, it is evidenced that the Ganhang, Nanling, Yanliao, Da Hinggan Ling and other tectono\|volcanic belts possess favorable geological conditions for the formation of ssuperlarge ore deposits of the continental volcanic rock type. The intersecting and overlapping locations of the aforementioned main belts with other tectono\|volcanic (\|intrusive) belts are the most potential areas where the superlarge continental volcanic rock\|type uranium deposits would be found.展开更多
There are three types of gold deposits in the Jiaodong gold metallogenetic domain. The strata\|bound gold deposits are a new type, which occur in a hydrocarbon\|gold double\|source bed enriched in gold (Au 174 ng/g) a...There are three types of gold deposits in the Jiaodong gold metallogenetic domain. The strata\|bound gold deposits are a new type, which occur in a hydrocarbon\|gold double\|source bed enriched in gold (Au 174 ng/g) and organic carbon (0.007%-4.225%). At diagenetic and hydrothermal stages water and oil were simultaneously activated and the strata\|bound gold deposits were formed from interactions between water, oil and rocks. In the late Yanshanian period, gold orebodies were enriched and enlarged in response to tectonomagmatism and action of complex ore\|forming hydrothermal solutions. As a result, it is highly expected to find suparlarge gold deposits and the Yanzi area is expected to be a perspective target area.展开更多
Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybd...Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in thepre-metallogenic and early-metallogenic epehs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction at middle to high temperatures (T = 250 -500℃) and lower W/R ratios (0. 1 > = W/R >0.001 ), while in the metallogenic and Post-metallogenic epochs, the ore-forming nuid was a residual fluid derived from meteoric water-wallrock interaction at midd1e to lower temperatures (T = 150 - 310℃ ) and relatively high W/Rratios (0. 5 >W/R≥0.1 ). The meteoric water played an important role in molybdenum min-eralization, and at the main metallogenic epoch the W/R ratio reached its maximum value.展开更多
Located in the Qinling (秦岭) molybdenum metallogenic belt on the southern margin of North China craton, the Nannihu (南泥湖) molybdenum (-tungsten) ore field, consisting of the Nannihu, Sandaozhuang (三道幢),...Located in the Qinling (秦岭) molybdenum metallogenic belt on the southern margin of North China craton, the Nannihu (南泥湖) molybdenum (-tungsten) ore field, consisting of the Nannihu, Sandaozhuang (三道幢), and Shangfang (上房) deposits, represents a superlarge skarn-porphyry molybdenum (-tungsten) accumulation. Outside the ore field, there are some hydrothermal lead-zinc-silver deposits found in recent years, for example, the Lengshuibeigou (冷水北沟), Yindonggou (银涧沟), Yangshuwa (杨树凹), and Yinhegou (银河沟) deposits. Ore-forming fluid geochemistry indicates that these deposits belong to the same metallogenic system. The hydrothermal solutions were mainly derived from primary magmatic water in the early stage and from the mixture of the primary magmatic water and meteoric water in the later stage, with an obvious decreasing tendency in temperature, salinity and gas-liquid ratio of fluid inclusions. Sulfur and lead isotope data show that the ore-forming substances and related porphyries were mainly derived from the lower crust, and a hidden magmatic chamber is indicated by aeromagnetic anomaly and drill hole data indicate that the Nannihu granite body extends to being larger and larger with depth increasing. The large-scale mineralization was the consequence of lithospheric extension during the late stage of the tectonic regime when the main compressional stress changed from NS-trending to EW-trending.展开更多
Longtoushan Sn-polymetal deposit is a large-scale deposit of high-tenor. The ore-bodies occur in reef limestone of middle Devonian. There is much anthraxolite in reef limestone and ore-bodies. The anthraxolite is the ...Longtoushan Sn-polymetal deposit is a large-scale deposit of high-tenor. The ore-bodies occur in reef limestone of middle Devonian. There is much anthraxolite in reef limestone and ore-bodies. The anthraxolite is the postmature result of oil-gas' thermal metamorphism. The close relationship of anthraxolite and Sn-polymetal deposit reveals the space-time relation between oil-gas evolution and Sn-polymetal mineralization. Sulfur isotope of Longtoushan deposit is close to oil's sulfur in Devonian, which indicates obvious relationship between the sulfur's source of deposit and oil-gas' activity. The forming of Longtoushan deposit relates to exhalative-sedimentary mineralization in Devonian. Because of the favorable hydrocarbon-forming condition of Longtoushan reef and surrounding basin facies' black shale and peat, coupling of ore-formation and hydrocarbon-forming occurs in seabed's hydrothermal convection. The distributing of ore-forming elements indicates the presence of hydrothermal convection system. The thermal fluid containing organic matters conduces to Sn-polymetal elements' activation and transfer, and provides catalyzing condition to the transforming from SO42- to S2-. The erosion action of brine containing organic acid to reef limestone induces the growing of crannies and karst's caverns, which provides advantageous space to Sn-polymetal mineralization. The heat source of mineralization provides thermocatalysis condition to hydrocarbon-forming. When the circulatory fluid containing oil-gas enters the high-temperature region(>150 ℃ ), the oil-gas is decomposed and anthraxolite comes into being.展开更多
The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the Tashan,Xianshuili,and Jiangxikeng...The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the Tashan,Xianshuili,and Jiangxikeng.However,the metallogenic mechanism of these deposits remains hotly debated.In this paper,two types of cassiterites(Cst1 and Cst2)have been identified in the Xianshuili and Jiangxikeng Sn deposits,which are hosted in the biotite-mylonite and garnetcordierite-muscovite blastomylonite,respectively.The euhedral Cst1(0.50–1.8 mm)coexists with biotite,feldspar,and quartz.It is platy and zoned with a mosaic structure.The subhedral to anhedral Cst2(0.02–0.35 mm)coexists with metamorphic minerals such as garnet and cordierite,and it is characterized by well-developed porosity and has no zonation.In-situ U-Pb dating of the Cst1 and Cst2 yielded ages of 149.5±1.0 Ma(MSWD=1.6,n=45)and 125.1±2.3 Ma(MSWD=4.5,n=43),respectively.Cst1 is most likely to be related to the intermediate-felsic magmatism that formed Gaojiping Group,whereas Cst2 has relatively high Ta,Nb,Fe,and W contents with obvious rare earth tetragroup effect,and may have formed by the late Early Cretaceous dynamic metamorphism.Results presented here,when combined with regional geology and geochemistry,led us to suggest that the Mesozoic intermediate-felsic volcanic rocks in the LMB are significantly enriched in Sn and F,with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related Cst1.In the late Early Cretaceous period,due to the NW-dipping subduction of the paleo-Pacific plate,the intermediate-felsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization,migration,and precipitation in the regional ductile shear zones,and eventually generating Sn mineralization.We propose that areas beneath Xianshuili and Jiangxikeng have great potential for discovery of new Sn resources.Our findings likely offer practical importance to regional geological ore prospecting.展开更多
基金financially supported by grants from the National Key Research and Development Project of China(2021YFC2901903 and 2017YFC0602705)the Jiangxi Province(2020101003)the East China University of Technology(1410000874)。
文摘The Jiajika granitic-and pegmatite-type lithium deposit,which is in the Songpan-Garze Orogenic Belt in western Sichuan Province,China,is the largest in Asia.Previous studies have examined the geochemistry and mineralogy of pegmatites and their parental source rocks to determine the genesis of the deposit.However,the evolution of magmatic-hydrothermal fluids has received limited attention.We analyzed He–Ar–H–O isotopes to decipher the ore-fluid nature and identify the contribution of fluids to mineralization in the late stage of crystallization differentiation.In the Jiajika ore field,two-mica granites,pegmatites(including common pegmatites and spodumene pegmatites),metasandstones,and schists are the dominant rock types exposed.Common pegmatites derived from early differentiation of the two-mica granitic magmas before they evolved into spodumene pegmatites during the late stage of the magmatic evolution.Common pegmatites have~3He/~4He ratios that vary from 0.18 to 4.68 Ra(mean1.62 Ra),and their~(40)Ar/~(36)Ar ratios range from 426.70 to 1408.06(mean 761.81);spodumene pegmatites have~3He/~4He ratios that vary from 0.18 to 2.66 Ra(mean 0.87Ra)and their~(40)Ar/~(36)Ar ratios range from 402.13 to 1907.34(mean 801.65).These data indicate that the hydrothermal fluids were shown a mixture of crust-and mantle-derived materials,and the proportion of crustderived materials in spodumene pegmatites increases significantly in the late stage of the magmatic evolution.Theδ~(18)OH_(2)O–VSMOWvalues of common pegmatites range from 6.2‰to 10.9‰,with a mean value of 8.6‰,andδDV–SMOWvalues vary from-110‰to-72‰,with a mean o f-85‰.Theδ~(18)OH_(2)O–VSMOWvalues of spodumene pegmatites range from 5.3‰to 13.2‰,with a mean of 9.1‰,andδDV–SMOWvalues vary from-115‰to-77‰,with a mean of-91‰.These data suggest that the ore-forming fluids came from primary magmatic water gradually mixing with more meteoric water in the late stage of the magmatic evolution.Based on the He–Ar–H–O and other existing data,we propose that the oreforming metals are mainly derived from the upper continental crust with a minor contribution from the mantle,and the fluid exsolution and addition of meteoric water during the formation of pegmatite contributed to the formation of the Jiajika superlarge lithium deposit.
基金the State Key BasicResearch Program ofChina(TG1999043203 ,TG1999043201) the Geological Survey Program(K1.4-3-4)under the Ministry of Land and Resources.
文摘The Dachang superlarge Sn-polymetal deposit in Guangxi, China, is one of the largest tin deposit all over the world. However, this deposit has long been in debate as to its origin. One of the opinions is that the Dachang deposit was formed by replacement of hydrothermal solution originating from Yanshanian granites, and the other is that this deposit was formed by submarine exhalation in the Devonian. This paper presents some new isotopic geochronology data obtained with the 40Ar-39Ar method for quartz and sanidine from massive ore in the No. 91 and No. 100 orebodies. Analytic results show that the No. 91 orebody was formed at 94.52±0.33 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz) or 91.4±2.9 Ma (the plateau age obtained with the 40Ar-39Ar method for feldspar), while the No. 100 orebody was formed at 94.56±0.45 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz), suggesting that both the No. 91 and the No. 100 orebodies were formed at the Late Yanshanian instead of the Devonian. The No. 100 orebody might be formed by filling of ore materials into caves in Devonian reef limestone. Because the ore-bearing solution released its pressure and lowered its temperature suddenly in a cave environment, ore minerals were formed concentratedly while water and other materials such as CO2 evaporated quickly, resulting less alteration of host rocks.
基金the Chinese Academy of Sciences (No. KXCX2-109) National Natural Science Foundation of China (No. 40304007 ,No.40172036)+1 种基金"Key Project of Science and Technology Research”(No. 01037) China Postdoctoral Science Foundation (No. 2003033238).
文摘Seventy-three large-superlarge deposits in China were formed in 4 metallogenic epochs, and located in 6 metallogenic domains. By combing their time-space distribution and the relevant data of crustal thickness, we discuss the control conditions of deep tectonics on superlarge deposits. The various spatial variation of the crustal thickness where deposits locate is closely related to their different tectonic setting. The crustal thickness of the region where deposits are in the Precatnbrian metallogenic epoch is 37.1 km and shows double-peak distribution, which is related to the different tectonic-mineralization processes in the Tarim-North China and Yangtze metallogenic domains. The crustal thickness of the region where deposits are in the Paleoproterozoic metallogenic epoch is 43.4 km and shows normal distribution, which is the result of 'pure' mineralization setting. The crustal thickness of the region where deposits are in the Late Palaeozoic-Early Mesozoic metallogenic epoch is about 41.2 km and shows multi-peak distribution, which can be related with dispersing distribution in the metallogenic domain of these superlarge deposits. The crustal thickness of the region where deposits are in the post-Indosinian metallogenic epoch is 37.3 km, and shows skew distribution, which resulted from different tectonic settings in eastern and western China.
文摘The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements and huminite reflectance. It is concluded that the source of Lincang superlarge deposit is mainly the muscovite granite in the west edge of the basin. During sedimentation, Ge (germanium) was leached out and entered the basin. Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes: peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO 2- 4 was reduced by coal organic matter. Pyrite and calcite formed. Hydrothermal process did not contribute significantly to mineralization.
文摘Based on the data base of 1285 mineral deposits of 22 commodities in 121 countries of 6 continents of the world, the authors use the linear trend analysis for their reserves to determine the cut-off limited order of reserves to select 36 exceptional superlarge (as peak mineral), 95 superlarge and 314 large deposits as new recognized intellect for their quantitative change. We have projected above 445 large-superlarge deposits on (1:5 M) global tectonic background map and divided 4 metallogenic domains, 21 metallogenic belts. Global metallogeny of large-superlarge deposits are: unity by endogenic, exogenic metamorphic and epigenetic in origin; speciality in different metallogenic domains and belts; preferentiality to ore-forming elements of Cu, Au, Fe, Ag, Cr, Mn, Zn, Pb, Sb, Hg, to continental margins or plate convergent belts, to Intra-continental tectono-magmatic complex belts and Large ductile shear zones; abnormality by the global oxyatmversion (excess oxygen atmospheric event) in Archean, redoxyatmversion (lack oxygen atmospheric event) in Proterozoic-Paleozoic, and tectonosphere thermal erosion (great amount of tectonic magmatic event) in Mesozoic-Cenozoic.
基金jointly funded by the Postdoctoral Research Fund of the Department of Human Resources and Social Security of Jiangxi Province(2016KY12)the Geological Prospecting Fund of Jiangxi Province(20160046)
文摘Objective The Mengshan area of the Xinyu City, Jiangxi Province is an important wollastonite production base in China. As early as the 90s of the 20th century, more than ten medium to small-sized wollastonite deposits, such as the Yueguangshan and Caofangmiao Deposits were discovered in the outer contact zone of the Mengshan rock mass. After that, no more progress was achieved in wollastonite prospection. In 2016, the project funded by the Geological Prospecting Fund of Jiangxi Province made significant breakthroughs in the "General Survey of the Shizhushan Wollastonite Ore in the Yushui District and Zhangmuqiao Wollastonite Ore in Shanggao County, Xinyu City, Jiangxi Province" in the Mengshan area. The new discovered Shizhushan Wollastonite Deposit has a scale of 50 million tons and its resources scale far exceeds that of the Seeleys Bay Wollastonite Deposit discovered in Canada.
文摘Based on the study of tens of geophysical profiles (seismic, geothermal flow and magnetotelluric sounding profiles) and 3-D shear wave velocity structures of the Chinese continent and its neighbouring regions, this paper describes the 3-D crustal and upper mantle structures and discusses briefly the deep geophysical background of superlarge ore deposits in the Chinese continent. Superlarge deposits are usually very few in number, but they are distributed still in certain forms such as “point”, “zone” and “area”. Most of the large-, medium- and small-sized deposits occur near the margins of different tectonic units; while the superlarge endogenic polymetallic deposits occur mostly in thinned mantle lithosphere, uplifts of the asthenosphere (vertical low-velocity zones) and the transformation zones of lateral inhomogeneity (weak zones) in the upper mantle. The superlarge endogenic polymetallic deposits are almost unevenly distributed in three major ore zones in China, corresponding to the boundaries of inhomogeneous regions in the asthenosphere.
文摘Interest in the ore\|forming histories of basins has grown rapid since 1960 and is now intensive. The main reason behind the acceleration is the increasing awareness that the natural processes responsible for generating metal deposits in the sedimentary basin from the source rocks of the beneath the basin and intensively hydrothermal activity in the basin. Observations made in different continental margin basin systems and superlarge deposits in Chinese Yunnan\|Guizhou\|Guangxi Province on the eastern margin of the Qingzang (Himalaya—Karakoram—Tibet) were investigated in terms of geodynamics of basin formation. Geotectonically, the area is situated in the conjoint between the Tethys—Himalaya and the Marginal\|Pacific tectonic domain, characterized by very complex geological structure, typical basin\|mountain tectonics, abundant Superlarge deposits.
文摘The superlarge Jinchang gold deposit is located in the joint area between the Taipingling uplift and the Laoheishan depression of the Xingkai Block in both eastern Jilin and eastern Heilongjiang Province. Wall rocks of the gold deposits are the Neoproterozoic Huangsong Group of metamorphic rocks. Yanshanian magmatism in this region can be divided into 5 phases, the diorite, the graphic granite, the granite, the granite porphyry and the diorite porphyrite, which resulted in the magmatic domes and cryptoexplosive breecia chimney followed by large-scale hydrothermal alteration. Gold mineralization is closely related to the fourth and fifth phase of magmatism. According to the occurrences, gold ores can be subdivided into auriferous pyritized quartz vein, auriferous quartz-pyrite vein, auriferous polymetailic sulfide quartz vein and auriferous pyritized calcite vein. The ages of the gold deposit are ranging from 122.53 to 119.40 Ma. The ore bodies were controlled by a uniform tectono-magmatic hydrothermal alteration system that the ore-forming materials were deep derived from and the ore-forming fluids were dominated by magmatic waters with addition of some atmospheric water in the later phase of mineralization. Gold mineralization took place in an environment of medium to high temperatures and medium pressures. Ore-forming fluids were the K^+-Na^+-Ca^2+-Cl^--SO4^2- type and characterized by medium salinity or a slightly higher, weak alkaline and weak reductive. Au in the ore-forming fluids was transported as complexes of [Au (HS)2]^-, [AuCl2]^-, [Au(CO2)]^- and [Au(HCO3)2]^-. Along with the decline of temperatures and pressures, the ore-forming fluids varied from acidic to weak acidic and then to weak alkaline, which resulted in the dissociation of the complex and finally the precipitation of the gold.
文摘The greenstone belt and metamorphosed microclastic rock\|type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies. Sedimentation, regional metamorphism and mineralization contributed a lot to the formation of the deposits, so did remelting magmatic process to some deposits, but the deposits were finally formed by reworking processes. The key factor leading to the formation of superlarge gold deposits is the reworking intensity, which for superlarge gold deposits is reflected by the large\|scale reworked source rocks and even ore materials of various sources, strongly oxidized ore\|forming fluids with a long and repeated active history and stable geothermal heat current. The factor which decides the reworking intensity is the network consisting of structures of different classes.
文摘The superlarge continental volcanic rock\|type uranium deposits, which were discovered abroad long ago, have not yet been reported up to now in China. This is an important problem that needs to be urgently solved by uranium geologists at present. In this paper, on the basis of analyzing the metallogenic settings and geological conditions of the superlarge continental volcanic rock\|type uranium deposits discovered in the world along with the metallogenic characteristics of those of the same type in China, the space\|time distribution patterns of continental volcanics and the metallogenic potential of main tectono\|volcanic belts in China are discussed, and a synthetic conclusion has been drawn that there is a possibility to discover the superlarge continental volcanic rock\|type uranium deposits in China. Moreover, it is evidenced that the Ganhang, Nanling, Yanliao, Da Hinggan Ling and other tectono\|volcanic belts possess favorable geological conditions for the formation of ssuperlarge ore deposits of the continental volcanic rock type. The intersecting and overlapping locations of the aforementioned main belts with other tectono\|volcanic (\|intrusive) belts are the most potential areas where the superlarge continental volcanic rock\|type uranium deposits would be found.
文摘There are three types of gold deposits in the Jiaodong gold metallogenetic domain. The strata\|bound gold deposits are a new type, which occur in a hydrocarbon\|gold double\|source bed enriched in gold (Au 174 ng/g) and organic carbon (0.007%-4.225%). At diagenetic and hydrothermal stages water and oil were simultaneously activated and the strata\|bound gold deposits were formed from interactions between water, oil and rocks. In the late Yanshanian period, gold orebodies were enriched and enlarged in response to tectonomagmatism and action of complex ore\|forming hydrothermal solutions. As a result, it is highly expected to find suparlarge gold deposits and the Yanzi area is expected to be a perspective target area.
文摘Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in thepre-metallogenic and early-metallogenic epehs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction at middle to high temperatures (T = 250 -500℃) and lower W/R ratios (0. 1 > = W/R >0.001 ), while in the metallogenic and Post-metallogenic epochs, the ore-forming nuid was a residual fluid derived from meteoric water-wallrock interaction at midd1e to lower temperatures (T = 150 - 310℃ ) and relatively high W/Rratios (0. 5 >W/R≥0.1 ). The meteoric water played an important role in molybdenum min-eralization, and at the main metallogenic epoch the W/R ratio reached its maximum value.
基金supported by the National Graduate Student Program of Building World-Class Universities (No. [2007]3020),China Scholarship CouncilState Key Laboratory of Geological Processes and Mineral Resources (No. GPMR200644), China University of Geosciences (Beijing)the National Natural Science Foundation of China (No. 40172036)
文摘Located in the Qinling (秦岭) molybdenum metallogenic belt on the southern margin of North China craton, the Nannihu (南泥湖) molybdenum (-tungsten) ore field, consisting of the Nannihu, Sandaozhuang (三道幢), and Shangfang (上房) deposits, represents a superlarge skarn-porphyry molybdenum (-tungsten) accumulation. Outside the ore field, there are some hydrothermal lead-zinc-silver deposits found in recent years, for example, the Lengshuibeigou (冷水北沟), Yindonggou (银涧沟), Yangshuwa (杨树凹), and Yinhegou (银河沟) deposits. Ore-forming fluid geochemistry indicates that these deposits belong to the same metallogenic system. The hydrothermal solutions were mainly derived from primary magmatic water in the early stage and from the mixture of the primary magmatic water and meteoric water in the later stage, with an obvious decreasing tendency in temperature, salinity and gas-liquid ratio of fluid inclusions. Sulfur and lead isotope data show that the ore-forming substances and related porphyries were mainly derived from the lower crust, and a hidden magmatic chamber is indicated by aeromagnetic anomaly and drill hole data indicate that the Nannihu granite body extends to being larger and larger with depth increasing. The large-scale mineralization was the consequence of lithospheric extension during the late stage of the tectonic regime when the main compressional stress changed from NS-trending to EW-trending.
文摘Longtoushan Sn-polymetal deposit is a large-scale deposit of high-tenor. The ore-bodies occur in reef limestone of middle Devonian. There is much anthraxolite in reef limestone and ore-bodies. The anthraxolite is the postmature result of oil-gas' thermal metamorphism. The close relationship of anthraxolite and Sn-polymetal deposit reveals the space-time relation between oil-gas evolution and Sn-polymetal mineralization. Sulfur isotope of Longtoushan deposit is close to oil's sulfur in Devonian, which indicates obvious relationship between the sulfur's source of deposit and oil-gas' activity. The forming of Longtoushan deposit relates to exhalative-sedimentary mineralization in Devonian. Because of the favorable hydrocarbon-forming condition of Longtoushan reef and surrounding basin facies' black shale and peat, coupling of ore-formation and hydrocarbon-forming occurs in seabed's hydrothermal convection. The distributing of ore-forming elements indicates the presence of hydrothermal convection system. The thermal fluid containing organic matters conduces to Sn-polymetal elements' activation and transfer, and provides catalyzing condition to the transforming from SO42- to S2-. The erosion action of brine containing organic acid to reef limestone induces the growing of crannies and karst's caverns, which provides advantageous space to Sn-polymetal mineralization. The heat source of mineralization provides thermocatalysis condition to hydrocarbon-forming. When the circulatory fluid containing oil-gas enters the high-temperature region(>150 ℃ ), the oil-gas is decomposed and anthraxolite comes into being.
基金supported by the Cooperative Research Fund of the CAS Key Laboratory of Mineralogy and Metallogeny(Grant No.KLMM20200201)the National Natural Science Foundation of China(Grant No.41903016)+2 种基金the President Youth Foundation from Guangzhou Institute of Geochemistry,Chinese Academy of Sciences(Grant No.2019SZJJ-08)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302013)the Mineral Geological Survey and Prospecting Prediction in Comprehensive Exploration Area of the China Geological Survey(Grant No.12120114015901)。
文摘The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the Tashan,Xianshuili,and Jiangxikeng.However,the metallogenic mechanism of these deposits remains hotly debated.In this paper,two types of cassiterites(Cst1 and Cst2)have been identified in the Xianshuili and Jiangxikeng Sn deposits,which are hosted in the biotite-mylonite and garnetcordierite-muscovite blastomylonite,respectively.The euhedral Cst1(0.50–1.8 mm)coexists with biotite,feldspar,and quartz.It is platy and zoned with a mosaic structure.The subhedral to anhedral Cst2(0.02–0.35 mm)coexists with metamorphic minerals such as garnet and cordierite,and it is characterized by well-developed porosity and has no zonation.In-situ U-Pb dating of the Cst1 and Cst2 yielded ages of 149.5±1.0 Ma(MSWD=1.6,n=45)and 125.1±2.3 Ma(MSWD=4.5,n=43),respectively.Cst1 is most likely to be related to the intermediate-felsic magmatism that formed Gaojiping Group,whereas Cst2 has relatively high Ta,Nb,Fe,and W contents with obvious rare earth tetragroup effect,and may have formed by the late Early Cretaceous dynamic metamorphism.Results presented here,when combined with regional geology and geochemistry,led us to suggest that the Mesozoic intermediate-felsic volcanic rocks in the LMB are significantly enriched in Sn and F,with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related Cst1.In the late Early Cretaceous period,due to the NW-dipping subduction of the paleo-Pacific plate,the intermediate-felsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization,migration,and precipitation in the regional ductile shear zones,and eventually generating Sn mineralization.We propose that areas beneath Xianshuili and Jiangxikeng have great potential for discovery of new Sn resources.Our findings likely offer practical importance to regional geological ore prospecting.