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Zhang J.,Jiangxi Provincial Institute of Geological Survey | Zhang J.,China University of Geosciences | Wang D.,Chinese Academy of Geological Sciences | Liu S.,Chinese Academy of Geological Sciences | And 3 more authors.
Acta Petrologica Sinica | Year: 2012

The northern Wuyi region, located in the conjoining area of the Yangtze plate and Cathaysian plate, is an important part of the Qinzhou-Hangzhou juncture zone and is characterized by series of Mesozoic volcanic basins. Systematic geochronological researches on its adjacent areas such as Lengshuikeng, Lizikeng and Xianxialing have been conducted, while in this area less research has been done. In this investigation, sphalerite was selected for isotopic chronological analyses. The Rb-Sr dating and Sm-Nd dating yields isochron ages of 135. 4 ±4. 4Ma (SMWD =0. 52) and 139 ± 15Ma (SMWD =0. 118), respectively. In addition, the C, O, S isotope compositions on lead-zinc ores and the associated calcite veins have been analyzed and 34SV-CDT of the lead and zinc minerals are 2. 5‰ ∼5. 1‰, 13CV-PDB of the calcite veins are - 2. 6%‰ ∼ -4. 7‰, 18OV-PDB are - 23. 9‰ ∼ -27. 7‰ and 18OV-PDB are 2. 3‰ ∼ 6. 2‰. These data suggest that S in the ores was derived from magmatic source, C and O in the calcite veins were originated not only from basic rocks or mantle source, but also from meteoric water. It is suggested that these deposits are magmatic deposits formed in the Early Cretaceous and that sphalerite can be used as an ideal mineral for dating. Our results provide new geochronological data for the volcanic belt in northern Wuyi, and reveal that metallogenetic age in Mesozoic became younger from west to east in general. The magmatic source of calcite veins leads to assumption that basement faults in northern Wuyi might extend deep to mantle, providing new evidences for constraining the south boundary of the Qinzhou-Hangzhou juncture.

Wang X.-H.,Chinese Academy of Geological Sciences | Hou Z.-Q.,Chinese Academy of Geological Sciences | Song Y.-C.,Chinese Academy of Geological Sciences | Wang G.-H.,Jiangxi Provincial Institute of Geological Survey | And 5 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2012

Located in Mesozoic strata of northern Lanping basin, Northwest of Yunnan Province, Baiyangping deposit is a sediment-hosted Pb-Zn-Cu-Ag polymetallic deposit controlled by fracture. In this paper, a study is carried out on the fluid inclusions in ore-forming stage calcite, quartz, sphalerite and C, O isotope of calcite and S, Pb isotope of sulfur-bearing minerals, on basis of which the character and source of ore-forming fluids and the source of ore-forming materials are discussed. The fluid inclusions of Baiyangping deposit are generally less than 10 μm, main gas-liquid phase. The ore-forming fluid system was Ca 2+-Na +-K +-Mg 2+ - Cl --F --NO 3 - brine system. The freezing temperature of fluid inclusions in mineral deposits ranges from -26.4 to -0.2°C, with an average of -14.6°C; the homogenization temperature is concentrated in 120-180°C, and the salinity varies from 0.35% to 24.73% (NaCl eq), with an average of 16.9% (NaCl eq). ore-forming fluid density is between 0.84 g/cm 3 and 1.11 g/cm 3, with an average of 1.04 g/cm 3, mineralization pressure is between 28.0 MPa and 46.9 MPa, with an average of 37.6 MPa; the corresponding mineralization depths is between 1058 m and 2452 m, with an average of 1555 m, concentrated in 1200 m to 1800 m; Carbon and oxygen isotope data indicate a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata. The ore-forming fluid belongs to the basin brine fluid system, which is mixed with the precipitate water; S isotope data show that sulfur in sulfides and sulphosalts is derived from thermochemical sulfate reduction, or the thermal decomposition of sulfur-bearing organic matter; the metal mineralization material is from sedimentary strata and basement.

Guo C.,Chinese Academy of Geological Sciences | Chen Z.,Chinese Academy of Geological Sciences | Lou F.,Jiangxi Provincial Institute of Geological Survey | Xu Y.,Southern Hunan Institute of Geology and Survey
Geotectonica et Metallogenia | Year: 2014

Late Jurassic, especially 150-160 Ma, is the most important period of W-Sn polymetallic mineralization in the Nanling region. The ore bearing granitoids are alkaline and high-potassium, and their major and trace element concentrations and Sr-Nd isotopic compositions are reviewed in this contribution. The ore bearing granites can be divided into two subgroups which are characterized by "sea-gull type-" and "inclining type-" REE patterns. Moreover, the two subgroups show distinct major and trace element and Sr-Nd isotopic characteristics. Ca/(Mg+Fe) vs. Al/(Mg+Fe) diagram shows that the two subgroups of granites were derived from different sources. SiO2 vs. P2O5, Rb vs. Y and Rb vs. Th diagrams also demonstrate that the W and Sn bearing granites are of different genetic types.

Tian S.,China University of Geosciences | Tian S.,Chinese Academy of Geological Sciences | Hou Z.,Chinese Academy of Geological Sciences | Su A.,Chinese Academy of Geological Sciences | And 8 more authors.
Acta Geologica Sinica | Year: 2012

Lithium separation technique for three reference materials has been established together with precise determination of lithium isotope using a Neptune multi collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). The solutions of lithium element standard reference materials, potassium, calcium, sodium, magnesium and iron single element, were used to evaluate analytical methods applied. Three separate stages of ion-exchange chromatography were carried out using organic cation-exchange resin (AG 50W-X8). Lithium was enriched for the three stages using different eluants, which are 2.8 M HCl, 0.15 M HCl and 0.5 M HCl in 30% ethanol, respectively. The columns for the first and second stages are made of polypropylene, and those for the third stage are made of quartz. Total reagent volume for the entire chemical process was 35 mL for three reference materials. The recovery yielded for the three stages is 98.9-101.2% with an average of 100.0%, 97.6-101.9% with an average of 99.9%, and 99.8-103.3% with an average of 100.6%, respectively. The precision of this technique is conservatively estimated to be ±0.72-1.04‰(2σ population), which is similar to the precision obtained by different authors in different laboratories with MC-ICP-MS. The δ 7Li values ( 7Li/ 6Li relative to the IRMM-016 standard) determined for andesite (AGV-2) and basalt (BHVO-2) are 5.68‰(n= 18), 4.33‰(n= 18), respectively. The δ 7Li value ( 7Li/ 6Li relative to the L-SVEC standard) determined for IRMM-016 is -0.01‰(n= 15). All these analytical results are in good agreement with those previously reported. In addition, the results for the same kinds of samples analyzed at the MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, are consistent with those obtained at the Plasma Laboratory, University of Maryland, within analytical uncertainty. According to these experiment results, it is concluded that this proposed procedure is a suitable method for determining the lithium isotopic composition of natural samples. © 2012 Geological Society of China.

Tian S.,Chinese Academy of Geological Sciences | Tian S.,China University of Geosciences | Hou Z.,Chinese Academy of Geological Sciences | Su A.,Chinese Academy of Geological Sciences | And 6 more authors.
Geochimica et Cosmochimica Acta | Year: 2015

Lithium concentrations and isotopic compositions of 38 carbonatites and associated syenites from the Maoniuping, Lizhuang, and Dalucao in western Sichuan, along with previously published and new Pb-Sr-Nd-C-O isotope data and whole-rock analyses, are used to constrain their mantle source and genesis. Carbonatites and syenites are characterized by extremely varying Li concentrations (0.8-120ppm) and highly variable Li isotopic compositions (-4.5‰ to +10.8‰). Among them, the majority of the carbonatites and syenites have δ7Li values between +0.2‰ and +5.8‰, which overlap with the reported values for MORB and OIB; 3 carbonatites have higher δ7Li values between +8.7‰ and +10.8‰; 5 carbonatites and 4 syenites have lighter δ7Li values between -4.5‰ and -0.3‰. These highly variable δ7Li compositions could not have been produced by diffusive-driven isotopic fractionation of Li and thus may record the isotopic signature of the late Proterozoic subcontinental lithospheric mantle (SCLM). This paper demonstrates the existence of anomalous δ7Li within the late Proterozoic subcontinental lithospheric mantle, suggesting that the ancient SCLM beneath western Sichuan was modified by interaction with fluids derived from the subducted oceanic crust and marine sediments.The modeling curves of fluids derived from a dehydrated slab (ratios: AOC80-SED20 to AOC40-SED60) with a representative mantle composition can account for the majority of lithium compositional variations. Some samples with unusual Pb-Sr-Nd-O isotopic compositions and highly variable δ7Li compositions are affected by significant involvement of marine sediments in their source region, not contaminated by crustal materials. The carbonatites and syenites in western Sichuan were generated by the partial melting of subcontinental lithospheric mantle, which was metasomatized by the Li-rich fluids derived from the subducted oceanic crust and marine sediments. This melting was most likely triggered by a Cenozoic asthenospheric mantle diapir related to Indian-Asian continental collision and post- or late-collisional stress relaxation in the Oligocene. © 2015 Elsevier Ltd.

Tian S.-H.,Chinese Academy of Geological Sciences | Yang Z.-S.,Chinese Academy of Geological Sciences | Hou Z.-Q.,Chinese Academy of Geological Sciences | Mo X.-X.,China University of Geosciences | And 3 more authors.
Gondwana Research | Year: 2015

New major and trace elemental, Sr-Nd-Pb isotope, and zircon U-Pb geochronological and Hf-O isotope data of post-collisional potassic and ultrapotassic volcanic rocks (PVRs and UPVs, respectively) along with geochemical data of PVRs, UPVs, and Mg-rich potassic rocks (MPRs) in the literature are used to constrain their mantle source and genesis. The PVRs, UPVs, and MPRs share similar geochemical features but with some discrepancies, suggesting that they were derived from subcontinental lithospheric mantle (SCLM) with isotopic heterogeneity resulting from the varying contributions of subducted Indian lower crust into the mantle source (ca. 6-20%, ca. 8-30%, and ca. 9-30%, respectively). The zircon Hf-O isotopic compositions of these rocks can be classified into two groups, including Group I rocks with high δ18O (6.7-11.3‰), low εHf(t) (-17.0 to -12.0), and old Hf crustal model ages (1.87-2.19Ga) that indicate an ancient SCLM source, and Group II rocks with δ18O values of 6.8-10.7‰, εHf(t) values of -11.8 to -6.3, and younger Hf crustal model ages (1.50-1.86Ga). The negative correlation defined by δ18O and εHf(t) of Group II samples suggests a two-component mixing between mantle- and crust-derived melts, in which the latter would be the subducted Indian lower crust as indicated by the similar negative εHf(t) values between Group II samples (-11.8 to -6.3) and the High Himalayan gneiss (-14.2 to +0.3). Thus we propose two enrichment events to account for the Hf-O isotopic compositions of the PVRs and UPVs/MPRs: the first involves the enrichment of the overlying SCLM that was metasomatized by fluids derived from dehydration of the subducted Indian lower crust, and the second invokes the enrichment of the overlying SCLM metasomatized by melts of the already dehydrated different proportions of the Indian lower crust. We argue that break-off of the northwards subducted Indian Plate in the early Miocene caused the asthenospheric upwelling under the Indian plate through slab window, resulting in varying degrees of partial melting of the overlying metasomatized heterogeneous SCLM to produce the primitive magmas of the PVRs, UPVs, and MPRs in an extensional setting. These observations and interpretations imply that the Indian lower crust was subducted beneath the Lhasa terrane in the Early-Middle Miocene. © 2015 International Association for Gondwana Research.

Shan Q.,CAS Guangzhou Institute of Geochemistry | Liao S.,Jiangxi Provincial Institute of Geological Survey | Lu H.,CAS Guangzhou Institute of Geochemistry | Lu H.,University of Quebec at Chicoutimi | And 5 more authors.
Acta Petrologica Sinica | Year: 2011

Qitianling granite is a complex massif with multi-stage intrusions during the Early Yanshanian Period. Petrochemical data show that it belongs to alkali-rich and highly evolved A-type granite formed in tension setting within a plate. The centimetre- and metre-sized pegmatoid cystidium and miarolitic quartz widely occurred in the second stage medium-fine grain biotite granite, implying that it is resulted from differentiation of the oversaturated-volatile magma. In addition, the coexist of melt-fluid inclusions and fluid inclusions in quartz indicated that the pegmatoid cystidium and miarolitic quartz were produced in the transition stage from granite magmatic melt to hydrothermal solution. The data of micro-thermometry showed that the trapped temperatures of melt-fluid inclusions are over 530°C, the homogenization temperatures of fluid inclusions are between 172°C and 454°C, indicating the temperature of fluids in hydrothermal stage, and the homogenization temperatures of fluid inclusions in sphalerite are between 285°C and 417°C, indicating the temperature and salinity of ore-forming fluid. Their evolution process from middle-fine grain biotite granite to pegmatoid cystidium to miarolitic quartz implied that magmatic and hydrothermal system underwent an evolution process: from volatile-rich fluid to melt and high salinity fluid to high salinity fluid to low salinity fluid and finally formed magmatic hydrothermal fluid in the CaCl2-NaCl-H2O-CO2 system. Based on the data of petrography and Raman spectrum of fluid inclusions, the existence of feldspar, calcite, rutile and metallic oxides in the fluid and crystal-rich melt-fluid inclusions implies that the captured fluids have a competent ore-forming potentiality.

Yang W.,CAS Guangzhou Institute of Geochemistry | Yang W.,University of Chinese Academy of Sciences | Su W.,Chinese Academy of science | Liao S.,Jiangxi Provincial Institute of Geological Survey | And 6 more authors.
Acta Petrologica Sinica | Year: 2011

Melt inclusion is consisting by the composition of original magma, which was sealed in minerals. It is the primary sample for the study of magmatic evolution and mineralization, for its preserving the physical and chemical information effectively during the formation of the hosted minerals in the primary magma. The melt inclusions from quartz phenocrysts and the melt-fluid inclusions from the pegmatitic shell was carried on the Linkam TS1500 and Renishaw RM-2000 laser Raman spectrometer, in this study. The results showed that the melting temperature of the melt inclusions at 750 ∼ 1027°C (average of 916°C), the homogenization temperatures of melt-fluid inclusion between 475 ∼650°C (average of 562°C), and combined with the presence of silicate minerals and rare earth minerals in inclusions show the magmatic-hydrothermal evolution of the Baerzhe granitic pluton directly, and give constraints on the mineralization of the super-large rare metals and rare earth deposit.

Yang W.B.,CAS Guangzhou Institute of Geochemistry | Yang W.B.,University of Chinese Academy of Sciences | Niu H.C.,CAS Guangzhou Institute of Geochemistry | Luo Y.,CAS Guangzhou Institute of Geochemistry | And 5 more authors.
Acta Petrologica Sinica | Year: 2010

The ultrapotassic magmatic rocks with tectonic significance have been confirmed at Bugula in Nileke, West Tianshan. It intruded in the Carboniferous Dahalajunshan Formation outcrop area is about 0.02km2 associated with the copper anomalous or mineralized zones. The ultrapotassic magmatic rocks show typical porphyritic texture, and the dominated phenociysts are K-feldspar, olivine and pyroxene with some residual leucite or its pseudomorph occasionally. The Bugula ultrapotassic magmatic rocks are defined as the plagioleucitites type of ultrapotassic rocks by means of their rock-forming minerals and geochemical characteristics. Their negative Nb, Ta, Zr, Hf, Ti anomalies and positive Pb anomaly in the trace element spider diagram suggest that the Bugula ultrapotassic magmatic rocks were formed in the orogenic stage. The trace element geochemical study indicaes that the ultrapotassic magma might be the products of partial melting of the phologopite-bearing garnet-spinel lherzolile occurred in the depth of a narrow range of 70km to 80km. A plateau age of 274.2 ± 1.6Ma of a flat 40Ar-39Ar spectrum was obtained for the ultrapotassic magmatic rocks by laser stepwise heating method. Its inverse isochron age of 274.3 ± 4.4Ma is agreed with the plateau age within analytical error. So, we suggested that the eastern Awulale Mountains were within the stage of orogenic evolution in Middle Permian at least on the basis of the geochemical and geochronological studies of the ultrapotassic magmatic rocks.

Guo C.,Chinese Academy of Geological Sciences | Chen Y.,Chinese Academy of Geological Sciences | Zeng Z.,Gannan Geological Survey Party of Jiangxi Province | Lou F.,Jiangxi Provincial Institute of Geological Survey
Lithos | Year: 2012

The Xihuashan tungsten deposit, located in the Nanling tungstentin province, is renowned for being one of the largest and the earliest exploited deposits of tungsten worldwide. It is a vein-type deposit genetically associated with the Xihuashan granite pluton. The granite was emplaced in four phases, and representative samples from each phase were analyzed using SIMS zircon UPb techniques, and the results indicate ages ranging from 161±3Ma to 158±2Ma (2σ). Whole rock analyses show the Xihuashan granitic rocks have high contents of SiO 2 (74.5wt.%-78.1wt.%) and total alkali (7.68wt.%-8.86wt.%), and their aluminum saturation index (ASI) values have a narrow range of 1.01-1.16. The second and third phases of the Xihuashan granite are enriched in heavy rare earth elements and are depleted in Eu, Ba, Sr, P and Ti. P 2O 5 vs SiO 2, zirconium saturation temperatures and zircon δ 18O values indicate that the Xihuashan granites are highly evolved I-S transformation-type. Whole rock ε Nd(t), zircon ε Hf(t) and δ 18O values fall into the ranges -11.3 to -10.4, -14.0 to -4.8, and 6.93‰-11.23‰ respectively, and the Nd and Hf two-stage model ages (T DM2) are 1.63-1.88Ga and 1.51-2.09Ga, respectively. The data indicate a primary reworking of Late Paleoproterozoic to Early Mesoproterozoic lower crust without any obvious participation of mantle material. The Xihuashan intrusion was emplaced at the same time as the widespread 165-150Ma I-type and A-type granites and syenites of the Nanling region, following the initiation in adjacent areas of intraplate basaltic activity, gabbros, bimodal volcanic rocks, and A-type granites from 190 to 165Ma. It can be inferred that the Nanling Range and neighboring regions were subjected to lithospheric extension during the Early Jurassic. © 2012.

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