Recent work has proved that Taylor’s model is inapplicable to the southern margin of the North China craton. The oxidation-reduction model for variation of REE patterns in the early Precambrian sediments is developed...Recent work has proved that Taylor’s model is inapplicable to the southern margin of the North China craton. The oxidation-reduction model for variation of REE patterns in the early Precambrian sediments is developed from theoretical study by appealing to the hard and soft acids and bases (HSAB) theory. The new model is in good consistency with the fact in this area, and will most likely be applicable to other areas.展开更多
An anomalous phase containing clays and humic acid was found while extraction humic acid from samples of weathering crust of REE-bearing granites by using 0.1 mol/L NaOH solution.Studied by chemical separation experim...An anomalous phase containing clays and humic acid was found while extraction humic acid from samples of weathering crust of REE-bearing granites by using 0.1 mol/L NaOH solution.Studied by chemical separation experiments,column chromatography,ion-exchange chromatography,infrared spectrum.fluorescence spectrum,polarimicroscopic testing and elemental determination by ultraviolet-visible spectrometer and atomic absorption spectrometer.it was proved to be a compound of humic acid and clays which are connected in the form of bridge by heteronuclearpolynuclear complexing ions formed by cations of RE￣(5+),Al￣(3+).Fe￣(3+) etc.The compounding pattern was further proved by the experiment for compounding humic acid,REE and kaolinite.展开更多
REE ratios and patterns for massive pyrite ore and massive cuprous pyrite ore ofthe Baiyinchang orefield are quite similar to those for quartz keratophyritic tuff and quartzalbitophyre of the same orefield. However, m...REE ratios and patterns for massive pyrite ore and massive cuprous pyrite ore ofthe Baiyinchang orefield are quite similar to those for quartz keratophyritic tuff and quartzalbitophyre of the same orefield. However, massive cuprous pyrite ore of the Ashele Cu-Zn de-posit is similar to basalt-diabase of the same district in REE geochemistry. Comparison of theChinese VMS ores with those from Rio Tinto, Spain and Que River, Australia, in REEgeochemistry has been made. REE ratios and patterns of bedded-massive and massive ores ofthe Changba-Lijiagou Zn-Pb deposit, the second largest SEDEX deposit in China are similarto those of their host rocks, the Qinling shales of Devonian age and the Changba adamellite.The three types of ore and their host rocks of the Dongshengmiao pyrite (pyrrhotite)-Zn-Pbdeposit have parallel REE ratios and patterns.展开更多
Unlike classic skarn-type scheelite deposits directly acquiring sufficient Ca2+ from surrounding limestones, all of the scheelite orebodies of the Shangfang tungsten(W) deposit occur mainly in amphibolite, and this pr...Unlike classic skarn-type scheelite deposits directly acquiring sufficient Ca2+ from surrounding limestones, all of the scheelite orebodies of the Shangfang tungsten(W) deposit occur mainly in amphibolite, and this provides a new perspective on the mineralization mechanism of W deposits. The ability of hydrothermal scheelite(CaWO4) to bind REE3+ in their Ca2+ crystal lattices makes it a useful mineral for tracing fluid-rock interactions in hydrothermal mineralization systems. In this study, the REE compositions of scheelite and some silicate minerals were measured systematically in-situ by laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) to assess the extent of fluid-rock interactions for the Late Mesozoic quartz-vein-type Shangfang W deposits. According to the variations in CaO and REE among scheelite and silicate minerals, the amphibole and actinolite in amphibolite may be able to release large amounts of Ca2+ and REE3+ into the ore-forming fluids during chlorite alteration, which is critical for scheelite precipitation. Furthermore, an improved batch crystallization model was adopted for simulating the process of scheelite precipitation and fluid evolution. The results of both the in-situ measurements and model calculations demonstrate that the precipitation of early-stage scheelite with medium rare-earth elements(MREE)-rich and [Eu/Eu*]N<1. The early-stage scheelite would consume more MREE than LREE and HREE of fluid, which will gradually produce residual fluids with strong MREE-depletion and [Eu/Eu*]N>1. Even though the partition coefficient of REE is constant, the later-stage scheelite will also inherit a certain degree of MREE-depletion and [Eu/Eu*]N future from the residual fluids. As a common mineral, sheelite forms in various types of hydrothermal ore deposits(e.g., tungsten and gold deposits). Hence, the improved batch crystallization model is also possible for obtaining detailed information regarding fluid evolution for other types of hydrothermal deposits. The results from model calculations also illustrate that the Eu anomalies of scheelite are not an effective index correlated to oxygen fugacity of fluids but rather are dominantly controlled by the continuous precipitation of scheelite.展开更多
REE composition of the carbonates of the auriferous quartz carbonate veins（QCVs） of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized RE...REE composition of the carbonates of the auriferous quartz carbonate veins（QCVs） of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.展开更多
AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization...AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization), different from setting groundwater (pH>6.5, with lower total REE contents, Ce depletion). While the AMD contaminated groundwater (pH=4.0-6.5) around tailings pond is characterized by transition from acidic to setting groundwater in total REE content, and associated with Ce depletion (like setting groundwater). The light REE in all type groundwater shows up depletion, but its depleted extent in acidic groundwater is more remarkable. This work indicates that REE behavior in AMD-type acidic groundwater is controlled mainly by pH value and metal (Al, Mn and Fe) contents. And the critical pH value that affects REE behavior in ground acidic water would be 4, lower than the previous value (pH=5) that has been believed prevalently in surface acidic waters. The pH could affect REE behavior in groundwater by controlling the solubility of metal (Al, Mn and Fe) hydroxides and the valence of cerium. Finally, light REE depletion in acidic groundwater may due to element affinity. High content Al (affinity with heavy REE) and low content Fe (affinity with light REE) may lead to heavy REE enrichment while light REE relative depletion in water.展开更多
文摘Recent work has proved that Taylor’s model is inapplicable to the southern margin of the North China craton. The oxidation-reduction model for variation of REE patterns in the early Precambrian sediments is developed from theoretical study by appealing to the hard and soft acids and bases (HSAB) theory. The new model is in good consistency with the fact in this area, and will most likely be applicable to other areas.
文摘An anomalous phase containing clays and humic acid was found while extraction humic acid from samples of weathering crust of REE-bearing granites by using 0.1 mol/L NaOH solution.Studied by chemical separation experiments,column chromatography,ion-exchange chromatography,infrared spectrum.fluorescence spectrum,polarimicroscopic testing and elemental determination by ultraviolet-visible spectrometer and atomic absorption spectrometer.it was proved to be a compound of humic acid and clays which are connected in the form of bridge by heteronuclearpolynuclear complexing ions formed by cations of RE￣(5+),Al￣(3+).Fe￣(3+) etc.The compounding pattern was further proved by the experiment for compounding humic acid,REE and kaolinite.
基金This study was part of two projects supported by the Natural Science Foudation of China and the Joint Open Laboratory of Nuclear Analytical Techniques,Chinese Academy of Sciences,respectively.
文摘REE ratios and patterns for massive pyrite ore and massive cuprous pyrite ore ofthe Baiyinchang orefield are quite similar to those for quartz keratophyritic tuff and quartzalbitophyre of the same orefield. However, massive cuprous pyrite ore of the Ashele Cu-Zn de-posit is similar to basalt-diabase of the same district in REE geochemistry. Comparison of theChinese VMS ores with those from Rio Tinto, Spain and Que River, Australia, in REEgeochemistry has been made. REE ratios and patterns of bedded-massive and massive ores ofthe Changba-Lijiagou Zn-Pb deposit, the second largest SEDEX deposit in China are similarto those of their host rocks, the Qinling shales of Devonian age and the Changba adamellite.The three types of ore and their host rocks of the Dongshengmiao pyrite (pyrrhotite)-Zn-Pbdeposit have parallel REE ratios and patterns.
基金financially supported by the National Science Foundation of China (No. 41803012)the China Postdoctoral Science Foundation (No. 2017M622546)。
文摘Unlike classic skarn-type scheelite deposits directly acquiring sufficient Ca2+ from surrounding limestones, all of the scheelite orebodies of the Shangfang tungsten(W) deposit occur mainly in amphibolite, and this provides a new perspective on the mineralization mechanism of W deposits. The ability of hydrothermal scheelite(CaWO4) to bind REE3+ in their Ca2+ crystal lattices makes it a useful mineral for tracing fluid-rock interactions in hydrothermal mineralization systems. In this study, the REE compositions of scheelite and some silicate minerals were measured systematically in-situ by laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) to assess the extent of fluid-rock interactions for the Late Mesozoic quartz-vein-type Shangfang W deposits. According to the variations in CaO and REE among scheelite and silicate minerals, the amphibole and actinolite in amphibolite may be able to release large amounts of Ca2+ and REE3+ into the ore-forming fluids during chlorite alteration, which is critical for scheelite precipitation. Furthermore, an improved batch crystallization model was adopted for simulating the process of scheelite precipitation and fluid evolution. The results of both the in-situ measurements and model calculations demonstrate that the precipitation of early-stage scheelite with medium rare-earth elements(MREE)-rich and [Eu/Eu*]N<1. The early-stage scheelite would consume more MREE than LREE and HREE of fluid, which will gradually produce residual fluids with strong MREE-depletion and [Eu/Eu*]N>1. Even though the partition coefficient of REE is constant, the later-stage scheelite will also inherit a certain degree of MREE-depletion and [Eu/Eu*]N future from the residual fluids. As a common mineral, sheelite forms in various types of hydrothermal ore deposits(e.g., tungsten and gold deposits). Hence, the improved batch crystallization model is also possible for obtaining detailed information regarding fluid evolution for other types of hydrothermal deposits. The results from model calculations also illustrate that the Eu anomalies of scheelite are not an effective index correlated to oxygen fugacity of fluids but rather are dominantly controlled by the continuous precipitation of scheelite.
基金funding through Minor Research Project from Indian School of Mines,Dhanbad and SERC,Department of Science & Technology,New Delhi,India
文摘REE composition of the carbonates of the auriferous quartz carbonate veins（QCVs） of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.
基金Project supported by the Science Foundation of Guangxi Province, ChinaProject supported by the Director Fund Project of Key Laboratory of Geological Engineering Center of Guangxi Province, China
文摘AMD(Acid Mine Drainage)-type acidic groundwater (pH<4) from oxidizing sulfide tailings in BS nickel mine (Western Australia) is of higher total rare earth element(REE) contents and Ce enrichment (PAAS normalization), different from setting groundwater (pH>6.5, with lower total REE contents, Ce depletion). While the AMD contaminated groundwater (pH=4.0-6.5) around tailings pond is characterized by transition from acidic to setting groundwater in total REE content, and associated with Ce depletion (like setting groundwater). The light REE in all type groundwater shows up depletion, but its depleted extent in acidic groundwater is more remarkable. This work indicates that REE behavior in AMD-type acidic groundwater is controlled mainly by pH value and metal (Al, Mn and Fe) contents. And the critical pH value that affects REE behavior in ground acidic water would be 4, lower than the previous value (pH=5) that has been believed prevalently in surface acidic waters. The pH could affect REE behavior in groundwater by controlling the solubility of metal (Al, Mn and Fe) hydroxides and the valence of cerium. Finally, light REE depletion in acidic groundwater may due to element affinity. High content Al (affinity with heavy REE) and low content Fe (affinity with light REE) may lead to heavy REE enrichment while light REE relative depletion in water.
