Based on the REE geochemistry data from the Baimazhai nickel deposit, Yunnan Province, the authors modeled the composition of the mantle source region by way of petrological mixing calculation, and further discussed t...Based on the REE geochemistry data from the Baimazhai nickel deposit, Yunnan Province, the authors modeled the composition of the mantle source region by way of petrological mixing calculation, and further discussed the genesis of this type of rocks. Both element geochemistry data and mixing calculation showed that lamprophyres in the Baimazhai nickel deposit were derived from a metasomatism-enrichment mantle and the fluids resulted from dehydration of a subducted slab which is comprised of ALK-, LREE- and incompatible element-rich sediments.展开更多
The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well develop...The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well developed. Enrichment of selenium in Se-rich ores is obviously controlled by stratigraphic position and lithological character. The closer the rocks are to the Maokou Formation cherts, the more they contain selenium, but in case the stratigraphic horizons are close to one another, the enrichment of selenium would be controlled by lithological character. In the Se ores and abandoned stone coal pile at the Yutangba Se deposit there have been found large amounts of independent Se minerals, for instance, achavalite and a variety of forms of native selenium. Native selenium minerals present in the abandoned stone coal pile are the outcome of a combination of natural factors and anthropologic activities. For example, lime making will create a closed environment favoring the growth of native selenium, and the reduction of selenium will lead to its secondary enrichment. Starting with the study of ore-forming fluids. Systematic studies have been conducted on fluid inclusions separated from the main ore veins in the mining district for their homogenization temperatures, salinities and density, and the results show that fluid inclusions contained in ores from the Yutangba Se deposit are large in number and diverse in form, dominated by primary ones. The homogenization temperatures of two types of fluid inclusions are within the range of {173.2}-{247.5℃}, individually up to 300℃ or even higher; the salinities of fluids in fluid inclusions in quartz and calcite are {5.9%}-{10.1%} and {3.9%}-{4.5%}, respectively; their densities vary from {0.79}-{0.93} g/cm+3. Extensive discovery of Se minerals due to secondary enrichment of selenium in the stone coal provides important clues to the improvements on the metallurgical and recovery technologies for selenium in the black shale series of China, and also is of great significance in expanding selenium reserves and relax the situation of lacking selenium resources on a global scale.展开更多
The Huize large-sized Pb-Zn deposit in Yunnan Province, China, is characterized by favorable metallogenic background and particular geological settings. This suggested that the ore-forming mechanism is relatively uniq...The Huize large-sized Pb-Zn deposit in Yunnan Province, China, is characterized by favorable metallogenic background and particular geological settings. This suggested that the ore-forming mechanism is relatively unique. On the basis of geological features such as the contents of mineralization elements, the REE concentrations of gangue calcites, the REE concentrations of calcite veins in the NE-trending tectonic zone and the Pb, Sr, C, H and O isotopic compositions of different minerals, this paper presents that the ore-forming materials and ore-forming fluids of the deposit were derived from various types of strata or rocks. This is a very significant conclusion for us to further discuss the mineralization mechanism of the deposit at depth and establish an available genetic model.展开更多
The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the ...The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the nature of source rocks in terms of the geochemical composition of sandstones. The major elements, rare\|earth elements and trace elements of the Mesozoic\|Cenozoic sandstones in the Lanping Basin are studied in this paper, revealing that the tectonic settings of the provenance for Mesozoic\|Cenozoic sedimentary rocks in the Lanping Basin belong to a passive continental margin and a continental island arc. Combined with the data on sedimentary facies and palaeogeography, it is referred that the eastern part of the basin is located mainly at the tectonic setting of the passive continental margin before Mesozoic, whereas the western part may be represented by a continental island arc. This is compatible with the regional geology data. The protoliths of sedimentary rocks should be derived from the upper continental crust, and are composed mainly of felsic rocks, mixed with some andesitic rocks and old sediment components. Therefore, the Lanping Mesozoic\|Cenozoic Basin is a typical continental\|type basin. This provides strong geochemical evidence for the evolution of the paleo\|Tethys and the basin\|range transition.展开更多
In order to get a better understanding of metallogeny, the geochemical characteristics of REE and trace element for Gejiu tin polymetallic deposits were studied by comparing concentrations of REE and trace elements in...In order to get a better understanding of metallogeny, the geochemical characteristics of REE and trace element for Gejiu tin polymetallic deposits were studied by comparing concentrations of REE and trace elements in different type ores and rocks, including skarn-type ore, bedded-type ore, vein-type ore, altered granite, country rocks. Results of this study indicated that the metallogenic matters for different type ores in the study area might be derived from the same origin source, which may be mainly related to granitic activities. Furthermore, there are some differences in concentrations of REE in different ores due to their different depositional mechanism during that time. LREE concentrations were enriched relatively in the vein-type ores and the bedded-type ores with relatively low total REE concentrations, whereas total REE concentrations were higher in the skarn-type ores with LREE and HREE concentrations in wide variation ranges.展开更多
Sr isotope geochemical studies (the87Sr/86Sr and δ18O-87Sr/86Sr systems) on the wall rocks and ores from the Lemachang independent Ag deposit in northeastern Yunnan provide strong evidence that the ore-forming fluids...Sr isotope geochemical studies (the87Sr/86Sr and δ18O-87Sr/86Sr systems) on the wall rocks and ores from the Lemachang independent Ag deposit in northeastern Yunnan provide strong evidence that the ore-forming fluids had flown through radiogenetically Sr-enriched rocks or strata prior to their entry into the locus of ore precipitation, and water-rock interaction is the main mechanism of Ag ore precipitation. The radiogenetically Sr-enriched source region may be the Proterozoic basement (the Kunyang and Hekou groups). Moreover, the theoretical modeling of the Sr isotopic system indicates that the ore-forming fluids contain as much as 3×10-6 Sr with isotopic composition of Sr being 0.750 and that of oxygen 7.0‰ The ore-forming temperatures were estimated at 150–250°C for the carbonate rock-type ores and at 200–260°C for the clastic rock-type.展开更多
Being stratiform or stratoid, the Huangbaishuwan witherite deposit at Ziyang and the Wenyuhe witherite-barite deposit at Zhushan occur in the lower Lower Cambrian siliceous rocks and the orebodies are remarkably contr...Being stratiform or stratoid, the Huangbaishuwan witherite deposit at Ziyang and the Wenyuhe witherite-barite deposit at Zhushan occur in the lower Lower Cambrian siliceous rocks and the orebodies are remarkably controlled by lithological character and petrography. Boron, carbon and oxygen isotopic studies of witherite, barytocalcite and calcite have shown that the car-bon, involved in the formation of these minerals, was derived mainly from hydrocarbons and bio-genetic gases resulting from degradation, polycondensation and dehydroxylation of bio-organic matter in sediments at the early stage of diagenesis; the boron was a mixture of boron in pore wa-ter and that released in the process of degradation of organic matter, with a minor amount of boron from cycling brines in the deep interior of the basin. Boron, carbon and oxygen isotopic studies unanimously demonstrated that witherite was precipitated in this sort of organic carbon-rich pore water medium during the early stage of diagenesis. Extensive occurrence of biodetritus and clastic texture in witherite ores strongly evidenced that Ba2+ was concentrated and settled down in the form of bio-barite on the seafloor as a result of biological processes, thereafter forming the initially enriched orebodies of barium deposits. Biological processes in seawater and early diagenesis in sediments are the major ore-forming mechanisms of witherite deposits in the region studied.展开更多
Based on the statistical and analytical data on more than 170 isotopic ages published since the 1980s of magmatic rocks, metamorphic rocks, tectonites and ores from the Western Kunlun Orogen, and the characteristics o...Based on the statistical and analytical data on more than 170 isotopic ages published since the 1980s of magmatic rocks, metamorphic rocks, tectonites and ores from the Western Kunlun Orogen, and the characteristics of sedimentation, magmatism, metamorphism and tectonic activities in the region studied in conjunction with geological field investigations and necessary supplementary isotope data, five stages of tectono-magmatic evolution, i.e. Ar3-Pt 2 1 tectono-magmatic active stage (I), pt 2 2 stable stage (II), Pt 3 1 -p2 active stage (III), T1-T2 stable stage (IV), and T3-Q active stage (V) can be distinguished in the Western Kunlun Orogen. Moreover, the tectono-magmatic active style and general trend, the characteristics of tectonic settings, etc. of each stage and substage in the region studied are also discussed.展开更多
Comprehensive studies, based on isotope geochemistry of C, H, O, S and Sr, chronology, common element and trace element geochemistry of fluid inclusions for the epithermal Au, As, Sb and Hg deposits in the Youjiang Ba...Comprehensive studies, based on isotope geochemistry of C, H, O, S and Sr, chronology, common element and trace element geochemistry of fluid inclusions for the epithermal Au, As, Sb and Hg deposits in the Youjiang Basin and its peripheral areas, suggested that the ore fluid was the basin fluid with abundant metallic elements and the large-scale fluid flow of the same source in the late Yenshan stage was responsible for huge epithermal mineralization and silicification. The ore fluid flowed from the basin to the platform between the basin and the platform and migrated from the inter-platform basin to the isolated platform in the Youjiang Basin. The synsedimentary faults and paleokast surface acted respectively as main conduits for vertical and lateral fluid flow.展开更多
Jinman vein copper deposit in western Yunnan occurs in a salt-bearing red clastic rock formation composed of sandstone, siltstone and shale. Wood texture is considerably developed in the ores. The metallic minerals ma...Jinman vein copper deposit in western Yunnan occurs in a salt-bearing red clastic rock formation composed of sandstone, siltstone and shale. Wood texture is considerably developed in the ores. The metallic minerals making up the wood textures mainly include pyrite, chalcopyrite and bornite. Studies on the samples and examination of their micrographs and electron micrographs have confirmed that they belong to xenoxylon, reflecting that the ore-hosting rock series is the product of sedimentation in the terrestrial environment. Organic geochemistry and sulfur and carbon isotopic composition data indicate that the formation of the deposit is substantially related with underground hot brines and biological processes.展开更多
Chrome-diopside is a common mineral in ultramafic rocks and kimberlites, whereasureyite has up to now only been found in some iron meteorites in Mexico and Burmesejade. The mineral species belonging to diopside-ureyit...Chrome-diopside is a common mineral in ultramafic rocks and kimberlites, whereasureyite has up to now only been found in some iron meteorites in Mexico and Burmesejade. The mineral species belonging to diopside-ureyite series in composition has been re-ported in kimberlite, Yakutia. Recently, a chromium-rich sodium展开更多
文摘Based on the REE geochemistry data from the Baimazhai nickel deposit, Yunnan Province, the authors modeled the composition of the mantle source region by way of petrological mixing calculation, and further discussed the genesis of this type of rocks. Both element geochemistry data and mixing calculation showed that lamprophyres in the Baimazhai nickel deposit were derived from a metasomatism-enrichment mantle and the fluids resulted from dehydration of a subducted slab which is comprised of ALK-, LREE- and incompatible element-rich sediments.
文摘The Yutangba Se deposit is a rare high-Se deposit in the world and it is well known for its high contents of Se, which reach 8590×10+{-6} . The ore-hosted rocks are dominated by cherts that have been well developed. Enrichment of selenium in Se-rich ores is obviously controlled by stratigraphic position and lithological character. The closer the rocks are to the Maokou Formation cherts, the more they contain selenium, but in case the stratigraphic horizons are close to one another, the enrichment of selenium would be controlled by lithological character. In the Se ores and abandoned stone coal pile at the Yutangba Se deposit there have been found large amounts of independent Se minerals, for instance, achavalite and a variety of forms of native selenium. Native selenium minerals present in the abandoned stone coal pile are the outcome of a combination of natural factors and anthropologic activities. For example, lime making will create a closed environment favoring the growth of native selenium, and the reduction of selenium will lead to its secondary enrichment. Starting with the study of ore-forming fluids. Systematic studies have been conducted on fluid inclusions separated from the main ore veins in the mining district for their homogenization temperatures, salinities and density, and the results show that fluid inclusions contained in ores from the Yutangba Se deposit are large in number and diverse in form, dominated by primary ones. The homogenization temperatures of two types of fluid inclusions are within the range of {173.2}-{247.5℃}, individually up to 300℃ or even higher; the salinities of fluids in fluid inclusions in quartz and calcite are {5.9%}-{10.1%} and {3.9%}-{4.5%}, respectively; their densities vary from {0.79}-{0.93} g/cm+3. Extensive discovery of Se minerals due to secondary enrichment of selenium in the stone coal provides important clues to the improvements on the metallurgical and recovery technologies for selenium in the black shale series of China, and also is of great significance in expanding selenium reserves and relax the situation of lacking selenium resources on a global scale.
文摘The Huize large-sized Pb-Zn deposit in Yunnan Province, China, is characterized by favorable metallogenic background and particular geological settings. This suggested that the ore-forming mechanism is relatively unique. On the basis of geological features such as the contents of mineralization elements, the REE concentrations of gangue calcites, the REE concentrations of calcite veins in the NE-trending tectonic zone and the Pb, Sr, C, H and O isotopic compositions of different minerals, this paper presents that the ore-forming materials and ore-forming fluids of the deposit were derived from various types of strata or rocks. This is a very significant conclusion for us to further discuss the mineralization mechanism of the deposit at depth and establish an available genetic model.
文摘The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the nature of source rocks in terms of the geochemical composition of sandstones. The major elements, rare\|earth elements and trace elements of the Mesozoic\|Cenozoic sandstones in the Lanping Basin are studied in this paper, revealing that the tectonic settings of the provenance for Mesozoic\|Cenozoic sedimentary rocks in the Lanping Basin belong to a passive continental margin and a continental island arc. Combined with the data on sedimentary facies and palaeogeography, it is referred that the eastern part of the basin is located mainly at the tectonic setting of the passive continental margin before Mesozoic, whereas the western part may be represented by a continental island arc. This is compatible with the regional geology data. The protoliths of sedimentary rocks should be derived from the upper continental crust, and are composed mainly of felsic rocks, mixed with some andesitic rocks and old sediment components. Therefore, the Lanping Mesozoic\|Cenozoic Basin is a typical continental\|type basin. This provides strong geochemical evidence for the evolution of the paleo\|Tethys and the basin\|range transition.
文摘In order to get a better understanding of metallogeny, the geochemical characteristics of REE and trace element for Gejiu tin polymetallic deposits were studied by comparing concentrations of REE and trace elements in different type ores and rocks, including skarn-type ore, bedded-type ore, vein-type ore, altered granite, country rocks. Results of this study indicated that the metallogenic matters for different type ores in the study area might be derived from the same origin source, which may be mainly related to granitic activities. Furthermore, there are some differences in concentrations of REE in different ores due to their different depositional mechanism during that time. LREE concentrations were enriched relatively in the vein-type ores and the bedded-type ores with relatively low total REE concentrations, whereas total REE concentrations were higher in the skarn-type ores with LREE and HREE concentrations in wide variation ranges.
文摘Sr isotope geochemical studies (the87Sr/86Sr and δ18O-87Sr/86Sr systems) on the wall rocks and ores from the Lemachang independent Ag deposit in northeastern Yunnan provide strong evidence that the ore-forming fluids had flown through radiogenetically Sr-enriched rocks or strata prior to their entry into the locus of ore precipitation, and water-rock interaction is the main mechanism of Ag ore precipitation. The radiogenetically Sr-enriched source region may be the Proterozoic basement (the Kunyang and Hekou groups). Moreover, the theoretical modeling of the Sr isotopic system indicates that the ore-forming fluids contain as much as 3×10-6 Sr with isotopic composition of Sr being 0.750 and that of oxygen 7.0‰ The ore-forming temperatures were estimated at 150–250°C for the carbonate rock-type ores and at 200–260°C for the clastic rock-type.
基金the“97’One Hundred Qualified Personnel Program”sponsored the Chinese Academy of Sciences+2 种基金the Climbing Program sponsored by Ministry of Science and Technology(Grant No.95-yu-39)the State Science Foundation for Outstanding Young Scientis ts(Grant No.49625304) the State Key Basic Research and Development Plan(Grant No.G1999045708).
文摘Being stratiform or stratoid, the Huangbaishuwan witherite deposit at Ziyang and the Wenyuhe witherite-barite deposit at Zhushan occur in the lower Lower Cambrian siliceous rocks and the orebodies are remarkably controlled by lithological character and petrography. Boron, carbon and oxygen isotopic studies of witherite, barytocalcite and calcite have shown that the car-bon, involved in the formation of these minerals, was derived mainly from hydrocarbons and bio-genetic gases resulting from degradation, polycondensation and dehydroxylation of bio-organic matter in sediments at the early stage of diagenesis; the boron was a mixture of boron in pore wa-ter and that released in the process of degradation of organic matter, with a minor amount of boron from cycling brines in the deep interior of the basin. Boron, carbon and oxygen isotopic studies unanimously demonstrated that witherite was precipitated in this sort of organic carbon-rich pore water medium during the early stage of diagenesis. Extensive occurrence of biodetritus and clastic texture in witherite ores strongly evidenced that Ba2+ was concentrated and settled down in the form of bio-barite on the seafloor as a result of biological processes, thereafter forming the initially enriched orebodies of barium deposits. Biological processes in seawater and early diagenesis in sediments are the major ore-forming mechanisms of witherite deposits in the region studied.
基金Project supported by the State Key Science and Technology Program (No. 305) for the Ninth Five-Year Plan Period of China.
文摘Based on the statistical and analytical data on more than 170 isotopic ages published since the 1980s of magmatic rocks, metamorphic rocks, tectonites and ores from the Western Kunlun Orogen, and the characteristics of sedimentation, magmatism, metamorphism and tectonic activities in the region studied in conjunction with geological field investigations and necessary supplementary isotope data, five stages of tectono-magmatic evolution, i.e. Ar3-Pt 2 1 tectono-magmatic active stage (I), pt 2 2 stable stage (II), Pt 3 1 -p2 active stage (III), T1-T2 stable stage (IV), and T3-Q active stage (V) can be distinguished in the Western Kunlun Orogen. Moreover, the tectono-magmatic active style and general trend, the characteristics of tectonic settings, etc. of each stage and substage in the region studied are also discussed.
文摘Comprehensive studies, based on isotope geochemistry of C, H, O, S and Sr, chronology, common element and trace element geochemistry of fluid inclusions for the epithermal Au, As, Sb and Hg deposits in the Youjiang Basin and its peripheral areas, suggested that the ore fluid was the basin fluid with abundant metallic elements and the large-scale fluid flow of the same source in the late Yenshan stage was responsible for huge epithermal mineralization and silicification. The ore fluid flowed from the basin to the platform between the basin and the platform and migrated from the inter-platform basin to the isolated platform in the Youjiang Basin. The synsedimentary faults and paleokast surface acted respectively as main conduits for vertical and lateral fluid flow.
基金the Major Basic Research Program of the People's Republic of China(Grant No. G1999043208), by the "One Hundred Personnel Program" Foundation of Chinese Academy of Sciences, by "Breakthroughs in Intellect" Foundation of Chinese Academy of Sciences (No. KZ
文摘Jinman vein copper deposit in western Yunnan occurs in a salt-bearing red clastic rock formation composed of sandstone, siltstone and shale. Wood texture is considerably developed in the ores. The metallic minerals making up the wood textures mainly include pyrite, chalcopyrite and bornite. Studies on the samples and examination of their micrographs and electron micrographs have confirmed that they belong to xenoxylon, reflecting that the ore-hosting rock series is the product of sedimentation in the terrestrial environment. Organic geochemistry and sulfur and carbon isotopic composition data indicate that the formation of the deposit is substantially related with underground hot brines and biological processes.
基金Project supported by the China Climb Program Foundationthe National Natural Science Foundation of China.
文摘Chrome-diopside is a common mineral in ultramafic rocks and kimberlites, whereasureyite has up to now only been found in some iron meteorites in Mexico and Burmesejade. The mineral species belonging to diopside-ureyite series in composition has been re-ported in kimberlite, Yakutia. Recently, a chromium-rich sodium
