The Lunggar iron deposit belongs to the Bangong-Nujiang metallogenic belt and is located in central Lhasa on the Tibetan Plateau.In the Lunggar deposit,iron mineralization formed in the skarnization contact zone betwe...The Lunggar iron deposit belongs to the Bangong-Nujiang metallogenic belt and is located in central Lhasa on the Tibetan Plateau.In the Lunggar deposit,iron mineralization formed in the skarnization contact zone between the Early Cretaceous granodiorite and the late Permian Xiala Formation limestone.In this study,we achieved detailed zircon U-Pb-Hf isotopes and mineral chemistry for the Early Cretaceous granodiorite.Zircon U-Pb dating results indicate that the Early Cretaceous granodiorite emplaced at ca.119 Ma.Based on the trace elements in zircons and the mineral chemical composition of amphibole and biotite,the Early Cretaceous granodiorite was believed to form under condition of high temperature(>700°C),low pressure(100400 MPa),and relatively high oxygen fugacity(lgfO2)(13.6 to 13.9)and H2O content(4%8%).Zircon trace elements,Hf isotope and biotite chemistry collectively reveal that significant juvenile mantle-derived magmas contributed to the source of the granodiorite.The relatively high logfO2 and shallow magma chamber are beneficial for skarn iron mineralization,implying remarkable potential for further prospecting in the Lunggar iron deposit.展开更多
Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were exam...Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were examined.The result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn（Ⅱ） and Pb（Ⅱ） from sphalerite and galena,respectively.It was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced oxidation.The oxidation equilibrium for sphalerite and galena took 3 and 4 d,respectively.About 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn（Ⅱ） and 89.0% Pb（Ⅱ） were recovered in 5 d,respectively.The unleached residual products were examined by X-ray diffraction for sphalerite,revealing the presence of elemental sulphur（S）,zinc sulphate（ZnSO4） and few traces of calcium aluminate（Ca3Al2O6）.The XRD pattern also indicates the presence of elemental sulphur（S）,lead sulphate（PbSO4） and few traces of itoite [Pb（S,Ge）（O,OH）4] and cobalt lead silicate [Pb8Co（Si2O7）3] in the unleached galena ore.展开更多
The Tayuan(Cu-Mo)-Pb-Zn deposit is located in the northern part of Daxinganling,NE China.Lenticular ore body occurs in the skarn zone.The skarn minerals mainly include garnet,pyroxene,epidote and wollastonite.Electron...The Tayuan(Cu-Mo)-Pb-Zn deposit is located in the northern part of Daxinganling,NE China.Lenticular ore body occurs in the skarn zone.The skarn minerals mainly include garnet,pyroxene,epidote and wollastonite.Electron microprobe analysis shows that the end member of garnet is mainly andradite(Ad_(62-97)Gr_(11-45),the pyroxene is mainly diopside,and epidote is mainly clinozoisite.These characteristics indicate that the Tayuan polymetallic skarn deposit is mainly calcareous skarn.Sometimes the content zonation can be observed in garnets.With one garnet crystal,content is shifty from the core to the rim.In general,the iron content in the core is higher than in the edge.The content in the garnet shows that the garnet in the Tayuan deposit formed from weak oxidation in alkaline environment with the oxygen fugacity increasing,suggesting that the hydrothermal fluid evolved from an acidic to a slight alkaline state.In the Tayuan polymetallic deposit,the ratio of Mn/Fe in pyroxene is about 1.3,and of Mg/Fe,it is about 2.The components of garnet in the Tayuan deposit plot in the field of the typical skarn Zn,Cu,Mo deposits in the world.展开更多
The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located...The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located in the western part of Yunkai Area, with an abundance of Pubei batholiths. Zircon U–Pb geochronology of Pubei batholiths shows that crystallization age ranges from 251.9 ± 2.2 to 244.3 ± 1.8 Ma, thus belonging to Indosinian orogeny. Geochemistry and Sr isotopic compositions of the Pubei batholiths show that it is derived from the partial melting of large scale crustal melting during the stage of exhumation and uplifting of the lower-middle crust. In addition, strontium isotope of sphalerite from the Xinhua Pb–Zn–(Ag) deposit, has limited ranges in ^(87)Rb/^(86)Sr and ^(87)Sr/^(86)Sr, ranging from 0.4077 to 1.0449, and 0.718720 to 0.725245, respectively. The initial ^(87)Sr/^(86)Sr ratios of sphalerite ranges between 0.718720 and 0.725245, which is higher than that of upper continental crust and lower than that of the Pubei batholiths, illustrating the fluid might be derived from the mixing of Pubei pluton and upper continental crust.展开更多
The Shazi deposit is a large-scale anatase deposit in Qinglong, Guizhou Province. Zircon grains from this deposit yielded a zircon U–Pb age of *259 Ma, representing the formation age of the deposit's parent rocks...The Shazi deposit is a large-scale anatase deposit in Qinglong, Guizhou Province. Zircon grains from this deposit yielded a zircon U–Pb age of *259 Ma, representing the formation age of the deposit's parent rocks.This age is identical to the eruption age of the Emeishan large igneous province, indicating a synchronous magmatic event. The rare-earth-element patterns of laterite samples were similar to those of the weathered basalt sample, and sub-parallel to those of the Emeishan high-Ti basalts,implying a genetic relationship between the laterite and the basalt. The Chemical Index of Alteration values of laterite ranged from 96 to 98, suggesting a high degree of weathering. SiO_2, MgO, and alkaline metal elements decreased with increasing degree of weathering, while Al_2O_3, Fe_2O_3,and TiO_2 increased. We found the highest TiO_2 in laterite and the lowest in pillow basalts, indicating that Ti migrated from basalt to laterite.Our U–Pb dating and whole-rock elemental geochemistry analyses suggest that the Emeishan basalt is the parent rock of the Shazi anatase ore deposit.Based on our analysis, we propose a metallogenic model to explain the ore-forming process, in which the karst terrain formed by the Emeishan mantle plume and the subsequent basaltic magma eruption were the key factors in the formation the Shazi anatase ore deposit.展开更多
Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considere...Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.展开更多
In this study, the Pb/U fractionation between zircon and uraninite during femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry （fs-LA-ICP-MS） analysis was studied in detail. The results show signi...In this study, the Pb/U fractionation between zircon and uraninite during femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry （fs-LA-ICP-MS） analysis was studied in detail. The results show significant Pb/U fractionation between zircon and uraninite during fs-LA-ICP-MS analysis that when calibrated against the zircon standard M257, the obtained U-Pb age of the Chinese national uraninite standard GBW04420 is 17% older than the recommended value. Thus, the accurate in-situ U-Pb dating of uraninite by LA-ICP-MS requires matrix-matched external standards for calibration. Uraninite in thin sections of two U-mineralized leucogranite from the Gaudeanmus in Namibia was analyzed by a fs-LA-ICP-MS equipped with a Signal Smooth Device （SSD）, using laser spot and frequency of 10 μm and 1 Hz, respectively. When calibrated using GBW04420 as the external standard, two samples give weighted mean 2066pb/238U ages of 504±3 Ma （2σ, n=21） and 503±3 Ma （2σ, n=22）, and only one of two samples yields a concordia U-Pb age of 507±1 Ma （2or, n=21）. These results are consistent with ID-TIMS U-Pb ages of 509±1 and 508±12 Ma and are also indistinguishable from zircon U-Pb upper intercept ages of 506±33 Ma （2σ, n=29） and 501±51 Ma （2σ, n=29）. The present study shows that in-situ U-Pb dating of uraninite can deliver more reliable formation ages of the deposit than dating coeval high-U zircon because the latter commonly suffer significant Pb loss after formation. Our results confirm that GBW04420 is an ideal matrix matching standard for in-situ U-Pb dating of uraninite.展开更多
Hyalophane-rich pegmatites are identified from the Manjinggou high-pressure granulite terrain in the Central Zone of North China Craton. Based on field investigation, mineral assemblage and mineral geochemistry, two t...Hyalophane-rich pegmatites are identified from the Manjinggou high-pressure granulite terrain in the Central Zone of North China Craton. Based on field investigation, mineral assemblage and mineral geochemistry, two types of pegmatites can be defined, i.e., hyalophane pegmatite and hyalophane-rich pegmatite. The hyalophane pegmatite is composed of pure hyalophane with 18.7 mol%-19.4 mol% celsian, whereas the hyalophane-rich pegmatite consists of clinopyroxene + titanite + epidote + hyalophane with 11.9 mol%-12.5 mol% celsian. Hyalophane-rich pegmatite has typical magmatic zircons with oscillatory zoning and high Th/U ratios, implying that this type of pegmatite crystallized from special melt similar to magma. SIMS (Cameca 1280) zircon U-Pb dating shows that the crystallization age of the hyalophane-rich pegmatite is 1812±5 Ma, younger than the regional metamorphic age (peak of ca. 1.85 Ga). Zircon δ18O (8.0 ‰-9.3 ‰) and ?Hf (-7.0 to-2.7) values measured by SIMS suggest that the high-pressure granulite terrain was the source of these veins. Therefore, the hyalophane-rich pegmatite veins were likely to be generated by melting of the high-pressure granulite terrain during post collisional uplift. A quick tectonic uplifting process with a velocity of 0.4 to 0.6 mm/a has been estimated for the high-pressure granulite terrane from the Central Zone of North China Craton.展开更多
基金Project(2018YSJS14)supported by the Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,China
文摘The Lunggar iron deposit belongs to the Bangong-Nujiang metallogenic belt and is located in central Lhasa on the Tibetan Plateau.In the Lunggar deposit,iron mineralization formed in the skarnization contact zone between the Early Cretaceous granodiorite and the late Permian Xiala Formation limestone.In this study,we achieved detailed zircon U-Pb-Hf isotopes and mineral chemistry for the Early Cretaceous granodiorite.Zircon U-Pb dating results indicate that the Early Cretaceous granodiorite emplaced at ca.119 Ma.Based on the trace elements in zircons and the mineral chemical composition of amphibole and biotite,the Early Cretaceous granodiorite was believed to form under condition of high temperature(>700°C),low pressure(100400 MPa),and relatively high oxygen fugacity(lgfO2)(13.6 to 13.9)and H2O content(4%8%).Zircon trace elements,Hf isotope and biotite chemistry collectively reveal that significant juvenile mantle-derived magmas contributed to the source of the granodiorite.The relatively high logfO2 and shallow magma chamber are beneficial for skarn iron mineralization,implying remarkable potential for further prospecting in the Lunggar iron deposit.
文摘Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were examined.The result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn（Ⅱ） and Pb（Ⅱ） from sphalerite and galena,respectively.It was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced oxidation.The oxidation equilibrium for sphalerite and galena took 3 and 4 d,respectively.About 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn（Ⅱ） and 89.0% Pb（Ⅱ） were recovered in 5 d,respectively.The unleached residual products were examined by X-ray diffraction for sphalerite,revealing the presence of elemental sulphur（S）,zinc sulphate（ZnSO4） and few traces of calcium aluminate（Ca3Al2O6）.The XRD pattern also indicates the presence of elemental sulphur（S）,lead sulphate（PbSO4） and few traces of itoite [Pb（S,Ge）（O,OH）4] and cobalt lead silicate [Pb8Co（Si2O7）3] in the unleached galena ore.
基金supported by the Natural Science Foundation of China(No.41203039)
文摘The Tayuan(Cu-Mo)-Pb-Zn deposit is located in the northern part of Daxinganling,NE China.Lenticular ore body occurs in the skarn zone.The skarn minerals mainly include garnet,pyroxene,epidote and wollastonite.Electron microprobe analysis shows that the end member of garnet is mainly andradite(Ad_(62-97)Gr_(11-45),the pyroxene is mainly diopside,and epidote is mainly clinozoisite.These characteristics indicate that the Tayuan polymetallic skarn deposit is mainly calcareous skarn.Sometimes the content zonation can be observed in garnets.With one garnet crystal,content is shifty from the core to the rim.In general,the iron content in the core is higher than in the edge.The content in the garnet shows that the garnet in the Tayuan deposit formed from weak oxidation in alkaline environment with the oxygen fugacity increasing,suggesting that the hydrothermal fluid evolved from an acidic to a slight alkaline state.In the Tayuan polymetallic deposit,the ratio of Mn/Fe in pyroxene is about 1.3,and of Mg/Fe,it is about 2.The components of garnet in the Tayuan deposit plot in the field of the typical skarn Zn,Cu,Mo deposits in the world.
基金supported by grants by the National Natural Science Foundation of China (No.41272097)the China Geological Survey Project (No.12120114016601)+1 种基金the Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences (Wuhan) (No.CUG120702)the Teaching Laboratory Foundation of China University of Geosciences (Wuhan) (No.SKJ2013085,SKJ2014010)
文摘The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located in the western part of Yunkai Area, with an abundance of Pubei batholiths. Zircon U–Pb geochronology of Pubei batholiths shows that crystallization age ranges from 251.9 ± 2.2 to 244.3 ± 1.8 Ma, thus belonging to Indosinian orogeny. Geochemistry and Sr isotopic compositions of the Pubei batholiths show that it is derived from the partial melting of large scale crustal melting during the stage of exhumation and uplifting of the lower-middle crust. In addition, strontium isotope of sphalerite from the Xinhua Pb–Zn–(Ag) deposit, has limited ranges in ^(87)Rb/^(86)Sr and ^(87)Sr/^(86)Sr, ranging from 0.4077 to 1.0449, and 0.718720 to 0.725245, respectively. The initial ^(87)Sr/^(86)Sr ratios of sphalerite ranges between 0.718720 and 0.725245, which is higher than that of upper continental crust and lower than that of the Pubei batholiths, illustrating the fluid might be derived from the mixing of Pubei pluton and upper continental crust.
基金supported by the Natural Science Foundation of China (Grant No.41262005)
文摘The Shazi deposit is a large-scale anatase deposit in Qinglong, Guizhou Province. Zircon grains from this deposit yielded a zircon U–Pb age of *259 Ma, representing the formation age of the deposit's parent rocks.This age is identical to the eruption age of the Emeishan large igneous province, indicating a synchronous magmatic event. The rare-earth-element patterns of laterite samples were similar to those of the weathered basalt sample, and sub-parallel to those of the Emeishan high-Ti basalts,implying a genetic relationship between the laterite and the basalt. The Chemical Index of Alteration values of laterite ranged from 96 to 98, suggesting a high degree of weathering. SiO_2, MgO, and alkaline metal elements decreased with increasing degree of weathering, while Al_2O_3, Fe_2O_3,and TiO_2 increased. We found the highest TiO_2 in laterite and the lowest in pillow basalts, indicating that Ti migrated from basalt to laterite.Our U–Pb dating and whole-rock elemental geochemistry analyses suggest that the Emeishan basalt is the parent rock of the Shazi anatase ore deposit.Based on our analysis, we propose a metallogenic model to explain the ore-forming process, in which the karst terrain formed by the Emeishan mantle plume and the subsequent basaltic magma eruption were the key factors in the formation the Shazi anatase ore deposit.
基金Supported by National Natural Science Foundation of China(No.41390444)
文摘Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.
基金supported by the National Natural Science Foundation of China(Grant Nos.41203027 and 41473031)the State Administration of Foreign Expert Affairs of China(Grant No.B07039)the Special Fund for Basic Scientific Research of Central Colleges,China University of Geosciences(Wuhan)(Grant No.CUGL140403)
文摘In this study, the Pb/U fractionation between zircon and uraninite during femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry （fs-LA-ICP-MS） analysis was studied in detail. The results show significant Pb/U fractionation between zircon and uraninite during fs-LA-ICP-MS analysis that when calibrated against the zircon standard M257, the obtained U-Pb age of the Chinese national uraninite standard GBW04420 is 17% older than the recommended value. Thus, the accurate in-situ U-Pb dating of uraninite by LA-ICP-MS requires matrix-matched external standards for calibration. Uraninite in thin sections of two U-mineralized leucogranite from the Gaudeanmus in Namibia was analyzed by a fs-LA-ICP-MS equipped with a Signal Smooth Device （SSD）, using laser spot and frequency of 10 μm and 1 Hz, respectively. When calibrated using GBW04420 as the external standard, two samples give weighted mean 2066pb/238U ages of 504±3 Ma （2σ, n=21） and 503±3 Ma （2σ, n=22）, and only one of two samples yields a concordia U-Pb age of 507±1 Ma （2or, n=21）. These results are consistent with ID-TIMS U-Pb ages of 509±1 and 508±12 Ma and are also indistinguishable from zircon U-Pb upper intercept ages of 506±33 Ma （2σ, n=29） and 501±51 Ma （2σ, n=29）. The present study shows that in-situ U-Pb dating of uraninite can deliver more reliable formation ages of the deposit than dating coeval high-U zircon because the latter commonly suffer significant Pb loss after formation. Our results confirm that GBW04420 is an ideal matrix matching standard for in-situ U-Pb dating of uraninite.
基金supported by National Natural Science Foundation of China (Grant Nos. 40730315 and 41023009)State Key Laboratory of Lithospheric Evolution
文摘Hyalophane-rich pegmatites are identified from the Manjinggou high-pressure granulite terrain in the Central Zone of North China Craton. Based on field investigation, mineral assemblage and mineral geochemistry, two types of pegmatites can be defined, i.e., hyalophane pegmatite and hyalophane-rich pegmatite. The hyalophane pegmatite is composed of pure hyalophane with 18.7 mol%-19.4 mol% celsian, whereas the hyalophane-rich pegmatite consists of clinopyroxene + titanite + epidote + hyalophane with 11.9 mol%-12.5 mol% celsian. Hyalophane-rich pegmatite has typical magmatic zircons with oscillatory zoning and high Th/U ratios, implying that this type of pegmatite crystallized from special melt similar to magma. SIMS (Cameca 1280) zircon U-Pb dating shows that the crystallization age of the hyalophane-rich pegmatite is 1812±5 Ma, younger than the regional metamorphic age (peak of ca. 1.85 Ga). Zircon δ18O (8.0 ‰-9.3 ‰) and ?Hf (-7.0 to-2.7) values measured by SIMS suggest that the high-pressure granulite terrain was the source of these veins. Therefore, the hyalophane-rich pegmatite veins were likely to be generated by melting of the high-pressure granulite terrain during post collisional uplift. A quick tectonic uplifting process with a velocity of 0.4 to 0.6 mm/a has been estimated for the high-pressure granulite terrane from the Central Zone of North China Craton.
