Objective The late Paleozoic Fe-Ti-V oxide deposit of the eastern Tianshan is an important orthomagmatic deposit type in the Central Asia Orogenic Belt （CAOB）. A series of Fe-Ti -V oxide deposits and mineralized ma...Objective The late Paleozoic Fe-Ti-V oxide deposit of the eastern Tianshan is an important orthomagmatic deposit type in the Central Asia Orogenic Belt （CAOB）. A series of Fe-Ti -V oxide deposits and mineralized mafic-ultramafic intrusions have been recognized recently, such as those in Hongliangzi, Weiya, Yaxi, Shaxinan and Shaxi on the Central Tianshan massif, and Niumaoquan on the southern margin of the Harlik belt （Shi et al., 2018a）. Only a few Fe -Ti-V oxide deposits in the eastern Tianshan （e.g., Weiya and Niumaoquan） have been studied, and their chronology need to be further constrained for study of regional Fe-Ti- V oxide metallogenic mechanism and variation of mantlederived magmas during the orogenic process.展开更多
Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralizatio...Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralization ages using the pitchblende U–Pb method have been published.These ages are commonly discordant and dispersed for abundant inclusions and an open U–Pb system.Zircon grains after strong hydrothermal alteration are usually characterized by high common Pb contents,and their U–Pb isochron ages recorded the hydrothermal alteration event without interference of common Pb components.The Hengjian gray/grayish-green granite porphyry experienced strong alteration by hydrothermal fluids during the pervasive uranium mineralization in the Xiangshan uranium ore field.Uranium mineralization in the Hengjian deposit may had different stages,and strong hydromicatization alteration occurred at a relatively early stage.Their altered zircon U–Pb isochron ages possibly represent relatively early mineralization age of the Xiangshan uranium deposits.Altered zircon grains from the Hengjian granite porphyry were analyzed using the secondary ion mass spectrometry(SIMS)U-Pb method in this study,and U–Pb isochron ages were measured to constrain the relatively early mineralization age of the Hengjian uranium deposit.展开更多
东天山为我国重要的铜、镍、金等成矿域(秦克章等,2002;2003;毛景文等,2002),许多学者对该区域进行过研究(倪志耀,1994;王登红等,2000;Xu et al.,2003;毛景文等,2002;王玉往等,2004;秦克章等,2003;2009;孙赫等,2006;2008;唐冬梅等,2009;...东天山为我国重要的铜、镍、金等成矿域(秦克章等,2002;2003;毛景文等,2002),许多学者对该区域进行过研究(倪志耀,1994;王登红等,2000;Xu et al.,2003;毛景文等,2002;王玉往等,2004;秦克章等,2003;2009;孙赫等,2006;2008;唐冬梅等,2009;2011;三金柱等,2007)。圪塔山口含硫化物镁铁-超镁铁质岩体位于东天山东段,紧邻康古尔-黄山深大断裂。展开更多
The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested th...The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.展开更多
The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition ...The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition from arc to initial collision.Here we present results from zircon U-Pb geochronology,whole-rock geochemistry,and Sr-Nd-Pb isotope geochemistry of the Beidaban granites to provide crucial information for geodynamic evolution of NQOB.Zircon U-Pb dating yields an age of 468±10 Ma for the Beidaban granites and most of the Beidaban samples contain amphibole,are potassium-rich,and have A/CNK values ranging from 0.7 to 0.9,illustrating that the Middle Ordovician Beidaban granites are K-rich,metaluminous,calc-alkaline granitoid.The geochemical characteristics indicate that the Beidaban granites are transitional I/S-type granitoids that formed in an arc setting.The isotopic compositions of initial(87 Sr/86 Sr)i values ranging from 0.70545 to 0.71082(0.70842 on average)andεNd(t)values ranging from−10.9 to−6.7(−8.8 on average)with two-stage Nd model ages(T DM2)of 1.74-2.08 Ga suggest that the Beidaban granites originated from Paleoproterozoic crustal materials.In addition,the initial Pb isotopic compositions(^(206)Pb/^(204)Pb=19.14-20.26;^(207)Pb/^(204)Pb=15.71-15.77;^(208)Pb/^(204)Pb=37.70-38.26)and geochemical features,such as high Th/Ta(17.43-30.12)and Rb/Nb(6.01-15.49)values,suggest that the Beidaban granite magma source involved recycled crustal components with igneous rocks.Based on these results in combination with previously published geochronological and geochemical data from other early Paleozoic igneous rocks,we suggest that the timing of the tectonic transition from arc to the initial collision to the fi nal closure of the North Qilian Ocean can be constrained to the Middle-Late Ordovician(ca.468–450 Ma).展开更多
Garnet is a primary mineral in skarn deposits and plays a significant role in recording copious mineralization and metallogenic information.This study systematically investigates the geochemistry and geochronology of ...Garnet is a primary mineral in skarn deposits and plays a significant role in recording copious mineralization and metallogenic information.This study systematically investigates the geochemistry and geochronology of garnet and zircon in the Dafang Au-Pb-Zn-Ag deposit,which represents prominent gold mineralization in southern Hunan,China.Garnet samples with distinct zoning patterns and compositional variations were identified using various analytical techniques,including Backscattered Electron(BSE)imaging,Cathodoluminescence(CL)response,textural characterization,and analysis of rare-earth elements(REE),major contents,and trace element compositions.The garnet was dated U-Pb dating,which yielded a lower intercept age of 161.06±1.93 Ma.This age is older than the underlying granodiorite porphyry,which has a concordia age of 155.13±0.95 Ma determined by zircon U-Pb dating.These results suggest that the gold mineralization may be related to the concealed granite.Two groups of garnet changed from depleted Al garnet to enriched Al garnet,and the rare earth element(REE)patterns of these groups were converted from light REE(LREE)-enriched and heavy REE(HREE)-depleted with positive europium(Eu)anomalies to medium REE(MREE)-enriched from core to rim zoning.The different REE patterns of garnet in various zones may be attributed to changes in the fluid environment and late superposition alteration.The development of distal skarn in the southern Hunan could be a significant indicator for identifying gold mineralization.展开更多
The Rauer Group is located on the eastern margin of the early Paleozoic Prydz Belt in East Antarctica,and the typical ultrahigh-temperature(UHT,>900℃)granulites outcrop on Mather Peninsula.However,the timing of UH...The Rauer Group is located on the eastern margin of the early Paleozoic Prydz Belt in East Antarctica,and the typical ultrahigh-temperature(UHT,>900℃)granulites outcrop on Mather Peninsula.However,the timing of UHT metamorphism and P–T path of the UHT granulites have long been debated,which is critical to understanding the tectonic nature and evolution history of the Prydz Belt.Thus,both a sapphirine-bearing UHT metapelitic granulite and a garnet-bearing UHT mafic granulite are selected for zircon SHRIMP U-Pb age dating.The results show that metamorphic zircon mantles yield weighted mean^(206)Pb/^(238)U ages of 918±29 Ma and 901±29 Ma for the metapelitic and mafic granulites,respectively,while zircon rims and newly grown zircons yield weighted mean^(206)Pb/^(238)U ages of 523±9 Ma and 532±11 Ma,respectively.These new zircon age data suggest that the UHT granulites may have experienced polymetamorphism,in which pre-peak prograde stage occurred in the early Neoproterozoic Grenvillian orogenesis(1000–900 Ma),whereas the UHT metamorphism occurred in the late Neoproterozoic to early Paleozoic Pan-African orogenesis(580–460 Ma).This implies that P–T path of the UHT granulites should consist of two separate high-grade metamorphic events including the Grenvillian and Pan-African events,which are supposed to be related to assembly of Rodinia and Gondwana supercontinents respectively,and hence the overprinting UHT metamorphic event may actually reflect an important intracontinental reworking.展开更多
基金financially supported by the National Key R&D Program of China(Grant No.2017YFC0601204)
文摘Objective The late Paleozoic Fe-Ti-V oxide deposit of the eastern Tianshan is an important orthomagmatic deposit type in the Central Asia Orogenic Belt （CAOB）. A series of Fe-Ti -V oxide deposits and mineralized mafic-ultramafic intrusions have been recognized recently, such as those in Hongliangzi, Weiya, Yaxi, Shaxinan and Shaxi on the Central Tianshan massif, and Niumaoquan on the southern margin of the Harlik belt （Shi et al., 2018a）. Only a few Fe -Ti-V oxide deposits in the eastern Tianshan （e.g., Weiya and Niumaoquan） have been studied, and their chronology need to be further constrained for study of regional Fe-Ti- V oxide metallogenic mechanism and variation of mantlederived magmas during the orogenic process.
基金financially supported by the National Key R&D Program of China(Grant No.2017YFC0602600)Project of Nuclear Power Development(No.HXS1403)Project of Core Competency Improvement(No.LTC1605).
文摘Objective The Hengjian uranium deposit is a typical hydrothermal deposit in the Xiangshan uranium ore field.The uranium mineralization ages of the Xiangshan deposits are poorly constrained,and only a few mineralization ages using the pitchblende U–Pb method have been published.These ages are commonly discordant and dispersed for abundant inclusions and an open U–Pb system.Zircon grains after strong hydrothermal alteration are usually characterized by high common Pb contents,and their U–Pb isochron ages recorded the hydrothermal alteration event without interference of common Pb components.The Hengjian gray/grayish-green granite porphyry experienced strong alteration by hydrothermal fluids during the pervasive uranium mineralization in the Xiangshan uranium ore field.Uranium mineralization in the Hengjian deposit may had different stages,and strong hydromicatization alteration occurred at a relatively early stage.Their altered zircon U–Pb isochron ages possibly represent relatively early mineralization age of the Xiangshan uranium deposits.Altered zircon grains from the Hengjian granite porphyry were analyzed using the secondary ion mass spectrometry(SIMS)U-Pb method in this study,and U–Pb isochron ages were measured to constrain the relatively early mineralization age of the Hengjian uranium deposit.
文摘东天山为我国重要的铜、镍、金等成矿域(秦克章等,2002;2003;毛景文等,2002),许多学者对该区域进行过研究(倪志耀,1994;王登红等,2000;Xu et al.,2003;毛景文等,2002;王玉往等,2004;秦克章等,2003;2009;孙赫等,2006;2008;唐冬梅等,2009;2011;三金柱等,2007)。圪塔山口含硫化物镁铁-超镁铁质岩体位于东天山东段,紧邻康古尔-黄山深大断裂。
基金supported by the Iran National Science Foundation(INSF)(Grant No.98012578)projects from the National Natural Science Foundation of China(Grant Nos.41473033,41673031)。
文摘The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.
基金This study was fi nancially supported by the Youth Science and Technology Talent Recruitment Project of Gansu Province(2022-19)Technological Innovation Project of Gansu Provincial Department of Natural Resources(2022-3,2022-4,2022-28)+2 种基金National Natural Science Foundation of China(Nos.42073059 and 42303034)Outstanding Youth Fund of Anhui Provincial Department of Education(No.2022AH020084)Doctoral Startup Foundation of Suzhou University(2021BSK038)。
文摘The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition from arc to initial collision.Here we present results from zircon U-Pb geochronology,whole-rock geochemistry,and Sr-Nd-Pb isotope geochemistry of the Beidaban granites to provide crucial information for geodynamic evolution of NQOB.Zircon U-Pb dating yields an age of 468±10 Ma for the Beidaban granites and most of the Beidaban samples contain amphibole,are potassium-rich,and have A/CNK values ranging from 0.7 to 0.9,illustrating that the Middle Ordovician Beidaban granites are K-rich,metaluminous,calc-alkaline granitoid.The geochemical characteristics indicate that the Beidaban granites are transitional I/S-type granitoids that formed in an arc setting.The isotopic compositions of initial(87 Sr/86 Sr)i values ranging from 0.70545 to 0.71082(0.70842 on average)andεNd(t)values ranging from−10.9 to−6.7(−8.8 on average)with two-stage Nd model ages(T DM2)of 1.74-2.08 Ga suggest that the Beidaban granites originated from Paleoproterozoic crustal materials.In addition,the initial Pb isotopic compositions(^(206)Pb/^(204)Pb=19.14-20.26;^(207)Pb/^(204)Pb=15.71-15.77;^(208)Pb/^(204)Pb=37.70-38.26)and geochemical features,such as high Th/Ta(17.43-30.12)and Rb/Nb(6.01-15.49)values,suggest that the Beidaban granite magma source involved recycled crustal components with igneous rocks.Based on these results in combination with previously published geochronological and geochemical data from other early Paleozoic igneous rocks,we suggest that the timing of the tectonic transition from arc to the initial collision to the fi nal closure of the North Qilian Ocean can be constrained to the Middle-Late Ordovician(ca.468–450 Ma).
基金financially supported by the National Key Research and Development Plan(Grant No.2023YFC2906801)。
文摘Garnet is a primary mineral in skarn deposits and plays a significant role in recording copious mineralization and metallogenic information.This study systematically investigates the geochemistry and geochronology of garnet and zircon in the Dafang Au-Pb-Zn-Ag deposit,which represents prominent gold mineralization in southern Hunan,China.Garnet samples with distinct zoning patterns and compositional variations were identified using various analytical techniques,including Backscattered Electron(BSE)imaging,Cathodoluminescence(CL)response,textural characterization,and analysis of rare-earth elements(REE),major contents,and trace element compositions.The garnet was dated U-Pb dating,which yielded a lower intercept age of 161.06±1.93 Ma.This age is older than the underlying granodiorite porphyry,which has a concordia age of 155.13±0.95 Ma determined by zircon U-Pb dating.These results suggest that the gold mineralization may be related to the concealed granite.Two groups of garnet changed from depleted Al garnet to enriched Al garnet,and the rare earth element(REE)patterns of these groups were converted from light REE(LREE)-enriched and heavy REE(HREE)-depleted with positive europium(Eu)anomalies to medium REE(MREE)-enriched from core to rim zoning.The different REE patterns of garnet in various zones may be attributed to changes in the fluid environment and late superposition alteration.The development of distal skarn in the southern Hunan could be a significant indicator for identifying gold mineralization.
基金supported by the National Nature Science Foundation of China(Grant no.41972050).
文摘The Rauer Group is located on the eastern margin of the early Paleozoic Prydz Belt in East Antarctica,and the typical ultrahigh-temperature(UHT,>900℃)granulites outcrop on Mather Peninsula.However,the timing of UHT metamorphism and P–T path of the UHT granulites have long been debated,which is critical to understanding the tectonic nature and evolution history of the Prydz Belt.Thus,both a sapphirine-bearing UHT metapelitic granulite and a garnet-bearing UHT mafic granulite are selected for zircon SHRIMP U-Pb age dating.The results show that metamorphic zircon mantles yield weighted mean^(206)Pb/^(238)U ages of 918±29 Ma and 901±29 Ma for the metapelitic and mafic granulites,respectively,while zircon rims and newly grown zircons yield weighted mean^(206)Pb/^(238)U ages of 523±9 Ma and 532±11 Ma,respectively.These new zircon age data suggest that the UHT granulites may have experienced polymetamorphism,in which pre-peak prograde stage occurred in the early Neoproterozoic Grenvillian orogenesis(1000–900 Ma),whereas the UHT metamorphism occurred in the late Neoproterozoic to early Paleozoic Pan-African orogenesis(580–460 Ma).This implies that P–T path of the UHT granulites should consist of two separate high-grade metamorphic events including the Grenvillian and Pan-African events,which are supposed to be related to assembly of Rodinia and Gondwana supercontinents respectively,and hence the overprinting UHT metamorphic event may actually reflect an important intracontinental reworking.
