Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous pro...Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous province （ELIP）, southwestern China. The Fo contents of olivine phenocrysts of komatiites with MgO-21.79 wt% range from 85.2% to 91.4%. The composition of unerupted parental melts is calculated from the compositions of the most Fo-rich olivine phenocrysts. These melts had -22 wt% MgO, and originated in mantle with a potential temperature of -1600℃ and at about 4.2 GPa pressure, supporting the conclusion that the generation of ELIP can be attributed to melting of a plume head beginning at -138 km depth.展开更多
The Haoyaoerhudong gold deposit,located in the northwestern part of the North China craton(NCC),has produced over 120 metric tonnes(t)of gold since 2007.It has a total reserve of>240 t at average gold grade of 0.62...The Haoyaoerhudong gold deposit,located in the northwestern part of the North China craton(NCC),has produced over 120 metric tonnes(t)of gold since 2007.It has a total reserve of>240 t at average gold grade of 0.62 g/t,making it one of the largest open pit gold mines in China.The steeply dipping,large-tonnage,low-grade,vein-or veinlet-type gold orebodies are hosted in strongly-deformed Mesoproterozoic carbonaceous schist of the Bayan Obo Group.The laminated/boudinaged veins/veinlets in the sinistral ductile-brittle shear zones are dominated by quartz,biotite,gold-bearing löllingite,pyr-rhotite,(arseno)pyrite,with minor native gold,titanite and xenotime.In this paper,we present new in situ U-Pb geochronological data on magmatic zircon from the preore dikes,on metamorphic and hydrothermal xenotime,and on hydrothermal titanite from the hydrothermally altered carbonaceous schist and auriferous quartzsulfides veins/veinlets,as well as He-Ar isotopic analysis on gold-bearing(arseno)pyrite in the syn-ore stage.The metamorphic xenotime U-Pb age of 426±6.0 Ma(2σ)records a regional metamorphic event,possibly related to the accretion of the Bainaimiao arc onto the NCC.Two pre-ore andesitic dikes yielded similar emplacement ages at~278 Ma constrained by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)U-Pb zircon data.Hydrothermal xenotime grains from the altered carbonaceous schist and auriferous quartz-sulfides veins yielded U-Pb ages of 256.0±4.1 Ma(2σ)and 254.4±2.1 Ma(2σ),respectively,overlapping with that of the hydrothermal titanite at 255.4±0.8 Ma(2σ)from the laminated quartz-sulfides veinlets.This indicates that the gold mineralization occurred at ca.255 Ma.The~255 Ma gold mineralization age is much younger than the previously reported Early-Middle Permian regional magmatic activity(ca.291 Ma to 268 Ma),and may be associated with the regional sinistral strike-slip event in the late orogenic cycle related to the collision between the Siberian craton and the NCC.The 3He/4He(R/Ra)and 40Ar/36Ar values of the gold-bearing(arseno)pyrite are 0.04 to 0.09(average=0.07)and 375.8 to 2023(average=1045),which reveal the ore-forming fluids dominantly originated from the crustal rocks,with limited involve-ment from the mantle.Collectively,our new geochronological data,noble gas isotopic analyses,and geo-logical evidence support a typical orogenic gold deposit model at Haoyaoerhudong.展开更多
Chromium,a strategic mineral resource in China,is widely used in high-precision equipment manufacturing.As the world's leading consumer and importer of chromite,China's external dependence exceeds 99%.The sign...Chromium,a strategic mineral resource in China,is widely used in high-precision equipment manufacturing.As the world's leading consumer and importer of chromite,China's external dependence exceeds 99%.The significant imbalance between domestic supply and demand seriously threatens national economic security.This study discusses the state of China's chromium resource supply from four aspects:the overview of domestic and global chromium resources,China's chromite production and import volume,the sources of imported chromite,and risk analysis.Considering the chromium industrial chain and factors such as production,consumption,and recovery tendency of chromium-bearing stainless steel,it is forecasted that China's demand for chromium ore will decline by 2040.This could considerably reduce the security situation of chromium resources.This study proposes five strategies for securing chromium resources:technological innovation,enhancing international cooperation and acquiring overseas resources,constructing a new pattern of“dual circulation”resource guarantee for sea-land transportation,encouraging chromium recycling,and building an emergency management system and strategic reserve mechanism for chromium resources.展开更多
Hydrothermal ore deposits at convergent plate boundaries represent extraordinary metal enrichment in the continental crust. They are generally associated with felsic magmatism in extensional settings at high thermal g...Hydrothermal ore deposits at convergent plate boundaries represent extraordinary metal enrichment in the continental crust. They are generally associated with felsic magmatism in extensional settings at high thermal gradients. Although their formation is common during accretionary orogeny, more and more ore deposits have been discovered recently in the collisional orogens of China. Because collisional orogeny was operated in a compressional regime at low thermal gradients, it is not favorable for mobilization of ore-forming elements and thus for the production of hydrothermal ore deposits. Nevertheless, continental collision is generally preceded by oceanic subduction, which enables the preliminary enrichment of ore-forming elements in the mantle wedge due to chemical metasomatism by subducting slab-derived fluids. This gave rise to metal pre-enriched domains in the overriding lithosphere, which may be reactivated by extensional tectonism for hydrothermal mineralization either immediately during accretionary orogeny or at a later time during and after collisional orogeny. It is these tectonic processes that have resulted in the progressive enrichment of ore-forming elements through the geochemical differentiation of the subducting oceanic crust, the metasomatic mantle domains and the mafic juvenile crust, respectively, at different depths. Finally, the reactivation of metal pre-enriched domains by continental rifting in the orogenic lithosphere is the key to the metallogenesis of collisional orogens.展开更多
The Baiyun deposit is a large gold deposit at the western end of the Liaoji rift zone in Liaoning Province, which has produced both auriferous quartz-vein type and altered-rock type mineralization. The ore bodies are ...The Baiyun deposit is a large gold deposit at the western end of the Liaoji rift zone in Liaoning Province, which has produced both auriferous quartz-vein type and altered-rock type mineralization. The ore bodies are mainly hosted in schist from the Gaixian Formation of the Liaohe Group. A detailed field geological survey showed that the quartz-vein type gold ore bodies are distributed in the near EW-trending and occur in the extensional tectonic space of schist in the Gaixian Formation, and the altered-rock type gold ore bodies are distributed in the near EW-trending structural belt and occur near in the Gaixian Formation of biotite schist, biotite granulite, marble and the upper footwall of dike. To further elucidate the source of ore-forming fluid and material in the Baiyun gold deposit, the H-O isotopes for quartz, S and Pb isotopes, in-situ trace elements for sulfides from quartz-vein and altered-rock type mineralization were studied. The H-O isotopic δD_(V-SMOW) and δ^(18)O_(H2O) values of the auriferous quartz range were from-88.8‰ to-82.2‰ and-1.95‰ to 4.85‰, respectively, suggests that the ore-forming fluids were mainly magmatic water with minor meteoric water. The distribution ranges of in-situ S isotopic compositions of Au-bearing pyrite in the quartz-vein type and altered-rock type ores were-8.38‰–-10.47‰(with average values of-7.89‰) and 11.38‰– 17.52‰(with average values of 11.55‰), respectively, indicating that the S isotopic compositions of the two ore types were clearly different. The in-situ Pb isotopic ratios changed almost uniformly, which showed that they had the same lead isotopic source. Based on the analysis of S and Pb isotopic compositions, the metallogenic materials in the Baiyun gold deposit were primarily from deep magma, and some wall rock materials may have been mixed in the metallogenic process. Co/Ni diagram shows that most Au-bearing pyrites have magmatic-hydrothermal or sedimentary alteration properties, and Au/As ratios were between 0.001 and 0.828(the average value was 0.07), indicating that the ore-forming fluid in the Baiyun gold deposit may have been deep magma. Combining the geological, trace element, and isotopic data, as well as data from previous studies, we propose that the Baiyun gold deposit is a magmatic-hydrothermal ore deposit.展开更多
Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages f...Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages from the diabase of the Aoyougou ophiolite previously put into Upper Lithologic Formation of the Zhulongguan Group are (1 840±2), (1 783±2) and (1 784±2) Ma respectively, whereas the zircon ages from the welded breccias in the Zhulongguan Group are (733±7), (738±4) and (604±6) Ma respectively. These results show that they should belong to the bottom of the middle Proterozoic and the upper part of upper Proterozoic respectively.展开更多
文摘Olivine phenocryst compositions and whole-rock chemical compositions are used to identify primitive picrite basalts from the early part of flood basalt successions in the western part of the Emeishan large igneous province （ELIP）, southwestern China. The Fo contents of olivine phenocrysts of komatiites with MgO-21.79 wt% range from 85.2% to 91.4%. The composition of unerupted parental melts is calculated from the compositions of the most Fo-rich olivine phenocrysts. These melts had -22 wt% MgO, and originated in mantle with a potential temperature of -1600℃ and at about 4.2 GPa pressure, supporting the conclusion that the generation of ELIP can be attributed to melting of a plume head beginning at -138 km depth.
基金financial support from the Academic-Industry Cooperation Project(grant HE1913)National Natural Science Foundation of China(41972094).
文摘The Haoyaoerhudong gold deposit,located in the northwestern part of the North China craton(NCC),has produced over 120 metric tonnes(t)of gold since 2007.It has a total reserve of>240 t at average gold grade of 0.62 g/t,making it one of the largest open pit gold mines in China.The steeply dipping,large-tonnage,low-grade,vein-or veinlet-type gold orebodies are hosted in strongly-deformed Mesoproterozoic carbonaceous schist of the Bayan Obo Group.The laminated/boudinaged veins/veinlets in the sinistral ductile-brittle shear zones are dominated by quartz,biotite,gold-bearing löllingite,pyr-rhotite,(arseno)pyrite,with minor native gold,titanite and xenotime.In this paper,we present new in situ U-Pb geochronological data on magmatic zircon from the preore dikes,on metamorphic and hydrothermal xenotime,and on hydrothermal titanite from the hydrothermally altered carbonaceous schist and auriferous quartzsulfides veins/veinlets,as well as He-Ar isotopic analysis on gold-bearing(arseno)pyrite in the syn-ore stage.The metamorphic xenotime U-Pb age of 426±6.0 Ma(2σ)records a regional metamorphic event,possibly related to the accretion of the Bainaimiao arc onto the NCC.Two pre-ore andesitic dikes yielded similar emplacement ages at~278 Ma constrained by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)U-Pb zircon data.Hydrothermal xenotime grains from the altered carbonaceous schist and auriferous quartz-sulfides veins yielded U-Pb ages of 256.0±4.1 Ma(2σ)and 254.4±2.1 Ma(2σ),respectively,overlapping with that of the hydrothermal titanite at 255.4±0.8 Ma(2σ)from the laminated quartz-sulfides veinlets.This indicates that the gold mineralization occurred at ca.255 Ma.The~255 Ma gold mineralization age is much younger than the previously reported Early-Middle Permian regional magmatic activity(ca.291 Ma to 268 Ma),and may be associated with the regional sinistral strike-slip event in the late orogenic cycle related to the collision between the Siberian craton and the NCC.The 3He/4He(R/Ra)and 40Ar/36Ar values of the gold-bearing(arseno)pyrite are 0.04 to 0.09(average=0.07)and 375.8 to 2023(average=1045),which reveal the ore-forming fluids dominantly originated from the crustal rocks,with limited involve-ment from the mantle.Collectively,our new geochronological data,noble gas isotopic analyses,and geo-logical evidence support a typical orogenic gold deposit model at Haoyaoerhudong.
基金supported by the Consulting Research Project of the Chinese Academy of Engineering (Nos.2022-XY-82,2023-XY-21,and 2023-XZ-25).
文摘Chromium,a strategic mineral resource in China,is widely used in high-precision equipment manufacturing.As the world's leading consumer and importer of chromite,China's external dependence exceeds 99%.The significant imbalance between domestic supply and demand seriously threatens national economic security.This study discusses the state of China's chromium resource supply from four aspects:the overview of domestic and global chromium resources,China's chromite production and import volume,the sources of imported chromite,and risk analysis.Considering the chromium industrial chain and factors such as production,consumption,and recovery tendency of chromium-bearing stainless steel,it is forecasted that China's demand for chromium ore will decline by 2040.This could considerably reduce the security situation of chromium resources.This study proposes five strategies for securing chromium resources:technological innovation,enhancing international cooperation and acquiring overseas resources,constructing a new pattern of“dual circulation”resource guarantee for sea-land transportation,encouraging chromium recycling,and building an emergency management system and strategic reserve mechanism for chromium resources.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB18020303)the National Key Basic Research Progam of China (2015CB856100)
文摘Hydrothermal ore deposits at convergent plate boundaries represent extraordinary metal enrichment in the continental crust. They are generally associated with felsic magmatism in extensional settings at high thermal gradients. Although their formation is common during accretionary orogeny, more and more ore deposits have been discovered recently in the collisional orogens of China. Because collisional orogeny was operated in a compressional regime at low thermal gradients, it is not favorable for mobilization of ore-forming elements and thus for the production of hydrothermal ore deposits. Nevertheless, continental collision is generally preceded by oceanic subduction, which enables the preliminary enrichment of ore-forming elements in the mantle wedge due to chemical metasomatism by subducting slab-derived fluids. This gave rise to metal pre-enriched domains in the overriding lithosphere, which may be reactivated by extensional tectonism for hydrothermal mineralization either immediately during accretionary orogeny or at a later time during and after collisional orogeny. It is these tectonic processes that have resulted in the progressive enrichment of ore-forming elements through the geochemical differentiation of the subducting oceanic crust, the metasomatic mantle domains and the mafic juvenile crust, respectively, at different depths. Finally, the reactivation of metal pre-enriched domains by continental rifting in the orogenic lithosphere is the key to the metallogenesis of collisional orogens.
基金supported by theNational Key Research and Development Program(No.2018YFC0603806)the Geological Surveying Project of China Geological Survey(No.DD20190166).
文摘The Baiyun deposit is a large gold deposit at the western end of the Liaoji rift zone in Liaoning Province, which has produced both auriferous quartz-vein type and altered-rock type mineralization. The ore bodies are mainly hosted in schist from the Gaixian Formation of the Liaohe Group. A detailed field geological survey showed that the quartz-vein type gold ore bodies are distributed in the near EW-trending and occur in the extensional tectonic space of schist in the Gaixian Formation, and the altered-rock type gold ore bodies are distributed in the near EW-trending structural belt and occur near in the Gaixian Formation of biotite schist, biotite granulite, marble and the upper footwall of dike. To further elucidate the source of ore-forming fluid and material in the Baiyun gold deposit, the H-O isotopes for quartz, S and Pb isotopes, in-situ trace elements for sulfides from quartz-vein and altered-rock type mineralization were studied. The H-O isotopic δD_(V-SMOW) and δ^(18)O_(H2O) values of the auriferous quartz range were from-88.8‰ to-82.2‰ and-1.95‰ to 4.85‰, respectively, suggests that the ore-forming fluids were mainly magmatic water with minor meteoric water. The distribution ranges of in-situ S isotopic compositions of Au-bearing pyrite in the quartz-vein type and altered-rock type ores were-8.38‰–-10.47‰(with average values of-7.89‰) and 11.38‰– 17.52‰(with average values of 11.55‰), respectively, indicating that the S isotopic compositions of the two ore types were clearly different. The in-situ Pb isotopic ratios changed almost uniformly, which showed that they had the same lead isotopic source. Based on the analysis of S and Pb isotopic compositions, the metallogenic materials in the Baiyun gold deposit were primarily from deep magma, and some wall rock materials may have been mixed in the metallogenic process. Co/Ni diagram shows that most Au-bearing pyrites have magmatic-hydrothermal or sedimentary alteration properties, and Au/As ratios were between 0.001 and 0.828(the average value was 0.07), indicating that the ore-forming fluid in the Baiyun gold deposit may have been deep magma. Combining the geological, trace element, and isotopic data, as well as data from previous studies, we propose that the Baiyun gold deposit is a magmatic-hydrothermal ore deposit.
文摘Single_zircon evaporation method was employed in the present study to determine the age of the iron_bearing rock series in Precambrian strata in the western sector of the northern Qilian Mountains. Three zircon ages from the diabase of the Aoyougou ophiolite previously put into Upper Lithologic Formation of the Zhulongguan Group are (1 840±2), (1 783±2) and (1 784±2) Ma respectively, whereas the zircon ages from the welded breccias in the Zhulongguan Group are (733±7), (738±4) and (604±6) Ma respectively. These results show that they should belong to the bottom of the middle Proterozoic and the upper part of upper Proterozoic respectively.
