The formation of Caosiyao giant porphyry Mo deposit is related to three granitic porphyries:coarse-grained granite porphyry(CG),fine-grained granite porphyry(FG),and giant plagioclase phenocryst bearing granite porphy...The formation of Caosiyao giant porphyry Mo deposit is related to three granitic porphyries:coarse-grained granite porphyry(CG),fine-grained granite porphyry(FG),and giant plagioclase phenocryst bearing granite porphyry(PG).To investigate the mineralization significance of three porphyries,Microthermometry,Laser micro-Raman Spectra,and H-O-He-Ar isotope analyses of fluid inclusions were conducted.Intermediate density with high temperatures(>550℃)and moderate-low salinities(~10 wt.%)characterizes CG-related initial exsolved fluids.Vapor-rich and brine phases separated from the initial fluid following a continuous decrease in pressure and temperature,inducing molybdenite precipitation.FG-related initial fluids are characterized by high temperatures(>550℃)and salinities(>65 wt.%).The mixing of low-salinity fluids led to a rapid decrease in the salinity of FG-related fluid,promoting the deposit of the Mo element.The lead-zinc mineralization is closely related to the FG-related fluid,and the addition of meteoric fluid induced the formation of galena and sphalerite.The ore-forming fluid related to the PG is CO_(2)-rich and accompanied by the addition of mantle-derived He-Ar.The presence of CO_(2) did not contribute to the solubility of Mo,resulting in the absence of a considerable amount of molybdenite.展开更多
Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mi...Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.展开更多
基金financially supported by the National Natural Science Foundation of China(No.42102084)the Special Research Fund of Natural Science(Special Post)of Guizhou University(No.2020[27])Guizhou Provincial Science and Technology Projects(No.ZK[2022]041)。
文摘The formation of Caosiyao giant porphyry Mo deposit is related to three granitic porphyries:coarse-grained granite porphyry(CG),fine-grained granite porphyry(FG),and giant plagioclase phenocryst bearing granite porphyry(PG).To investigate the mineralization significance of three porphyries,Microthermometry,Laser micro-Raman Spectra,and H-O-He-Ar isotope analyses of fluid inclusions were conducted.Intermediate density with high temperatures(>550℃)and moderate-low salinities(~10 wt.%)characterizes CG-related initial exsolved fluids.Vapor-rich and brine phases separated from the initial fluid following a continuous decrease in pressure and temperature,inducing molybdenite precipitation.FG-related initial fluids are characterized by high temperatures(>550℃)and salinities(>65 wt.%).The mixing of low-salinity fluids led to a rapid decrease in the salinity of FG-related fluid,promoting the deposit of the Mo element.The lead-zinc mineralization is closely related to the FG-related fluid,and the addition of meteoric fluid induced the formation of galena and sphalerite.The ore-forming fluid related to the PG is CO_(2)-rich and accompanied by the addition of mantle-derived He-Ar.The presence of CO_(2) did not contribute to the solubility of Mo,resulting in the absence of a considerable amount of molybdenite.
基金supported by the National Science and Technology Major Project(No.2024ZD1001005)the National Natural Science Foundation of China(No.42172103)+2 种基金the Natural Science Foundation of Hubei Province(Nos.2023AFD206,2024AFD401,2025AFD439,2025AFD452)the Research Fund Program of Hubei Key Laboratory of Resources and Eco-Environment Geology(Nos.HBREGKFJJ-202302,HBREGKFJJ-202402)the State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202424)。
文摘Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.
