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Zhang Q.,CAS Institute of Geology and Geophysics | Jin W.,CAS Institute of Geology and Geophysics | Li C.,Tianjin Center | Wang J.,Lanzhou University | And 3 more authors.
Geotectonica et Metallogenia | Year: 2015

It is of crucial important to identify the undiscovered intrusions in hydrothermal deposit prospecting. There are lots of effective methods to identify undiscovered intrusions, such as magnetic, electric, and gravitational methods. However, the vitrinite reflectance method for the geothermal indicator is a direct and simple method. Magmatic emplacement is bound to form a thermal field around, and form a temperature gradient field with the distance of magma and superimposed on the geothermal field. Therefore, we can find undiscovered intrusions through analysis of the variation of thermal field. If we know the heat transfer parameters of magma and surrounding rocks, we even can quantitatively determine the depth, the location and the scale of the undiscovered intrusion. The vitrinite reflectance (expressed as a Ro) method commonly used in coal and petroleum geology is a simple, economic, and effective method to identify undiscovered intrusion. The effective distance of the method is around a few meters to a few kilometers, depending on the size, composition, and depth of different intrusion. Regardless of the new and old mining area, you can try this method so long as there is post-Silurian mud rock. This method applies to the surface can also be applied to drilling. For old mining area, there are the research data for three dimension images, for new ones, the depth of Ro variation should be noted in order to guide the prospecting work in time. The authors argue that the intrusion is commonly associated with the fluid flow in the mining area. If Ro anomalies (Ro>2%) are found in the mining area, attention should be paid to the possibility of undiscovered intrusion and the accompanying mineralization in geological expectations. The authors hope that the introduction of this method, combining with the characteristics of hydrothermal ore deposit to the study of ore mineralization, will carve out a new application and make new progress in the deep prospecting. © 2015, Science Press. All right reserved. Source


Yang Z.,Beijing Institute of Geology and Mineral Resources | Yang Z.,Donia Resources Co. | Yang Z.,Central South University | Zhang W.,Donia Resources Co. | And 3 more authors.
Chinese Journal of Geochemistry | Year: 2012

The Sipu region of North Guangxi is located in the southwest of the "Jiangnan Ancient Land", where there are developed the oldest stratum in southern China, the Proterozoic Sipu Group, and there are also largely exposed mafic intrusive rocks, mafic volcanic rocks and copper-nickel sulfide deposits. Both mafic intrusive rocks and volcanic rocks are rich in MgO (6. 52%-26. 39%), but poor in K 2O (0. 05%-1. 00%) and TiO 2 (0. 33%-0. 89%). They are also rich in trace elements such as Rb and Ba while poor in Ta, Nb and the like. Both of them have medium contents of rare-earth elements, 30. 26×10 -6-126. 71×10 -6, in which LREEs are slightly rich with Σ LREE/Σ HREE of 1. 35-2. 46, δEu 0. 79-1. 33, displaying weak or no δEu anomaly, with the same geochemical features. The right-inclined distribution patterns and the features show that magma would be formed at the comagmatic undiagenetic stage. All studies show that mafic intrusive rocks and volcanic rocks are the products of the same source region evolving in different stages and times. The copper-nickel sulfide deposits are characterized by liquation, crystallization and fractionation of mafic rocks, and have some interrelations with mafic intrusive rocks and volcanic rocks with respect to magmatic genesis. © 2012 Science Press, Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg. Source


Zhen S.-M.,China University of Geosciences | Zhu X.-Y.,Beijing Institute of Geology and Mineral Resources | Du Z.-Z.,China University of Geosciences | Gong X.-D.,China University of Geosciences | And 3 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2012

The Xianrenyan pluton is located in the south of Shuikoushan ore field, Hunan Province. There develops Au, Cu, Mo and Zn mineralization in inner and outer contact zones of the pluton, which shows the colse relationship between the pluton and the metallic mineralization. Zircon LA-MC-ICP-MS U-Pb age of the monzonite suggests a weighted mean age of (156.09±0.46) Ma (MSWD=1.4) which implies that the pluton was emplaced in Early Yanshanian period. The in-situ Hf isotopic analysis reveals 176Hf/177Hf ratios in the zircon range from 0.282243 to 0.282904, and εHf(t) from -15.55 to 7.87 (with peak value around -10), and the two stage Hf model ages(TDM2) from 703 Ma to 2188 Ma(with peak value around 1800 Ma), which indicates that parental magma of the pluton was derived from the mixed sources of the lower crust and mantle. Based on the geochemistry of the rocks, it can be concluded that the monzonite was mainly resulted from remelting of the Mesoproterozoic basement rocks and formed in Middle and Late Jurassic when the crust was in an extension-thinning geodynamic setting. In addition, the authors compare and analyze the lithogeochemical characteristics of the Xianrenyan pluton and the Shuikoushan stock. The fact that the Xianrenyan pluton has a weaker differentiation than the Shuikoushan pluton gives the reason for its unfavorable gold mineralization. Source


Qi F.-Y.,China University of Geosciences | Zhang Z.,China University of Geosciences | Zhang Z.,Development and Research Center | Zhu X.-Y.,Beijing Institute of Geology and Mineral Resources | And 5 more authors.
Geology in China | Year: 2012

The Hangshaping large-size W-Mo polymetallic ore deposit lies in the Nanling metallogenic belt. The authros chose the skarn as well as wall rocks (limestone and marble)and ?granite porphyry related to the skarn to conduct component analysis. The result shows that the major elements (Fe, Al, Mg and Si) migrated between the granite porphyry and the skarn, and the content of SiO 2 shows linear descending relationship with the content of MgO, MnO, CaO and Fe 2O 3+FeO in the skarn. The skarn is enriched in LREE and depleted in HREE, with obvious Eu negative anomalies. The granite porphyry has the same REE distribution patterns as the skarn. The precise Re-Os dating of the molybdenite from skarn-type ore yielded an ore-forming age of 158.4±1.3 Ma. which is the same as the age of the granite porphyry, suggesting their relationship in petrogenesis. The poorlydeveloped Ce anomalies in skarn rocks imply that the fluids for the formation of skarn were mainly derived from the magma and mixed with meteoric water. Combined with the geochemical characteristics of different rocks, intense differentiation of LREE and HREE and Eu negative anomalies, the authors infer that the skarn in the Huangshaping ore deposit was formed by fluid metasomatism. Source


Zhang C.-L.,Nanjing Institute of Geology and Mineral Resources | Zhou G.,No.4 Geological Party | Wang H.-Y.,Nanjing Institute of Geology and Mineral Resources | Dong Y.-G.,Nanjing Institute of Geology and Mineral Resources | Ding R.-F.,Beijing Institute of Geology and Mineral Resources
Geological Bulletin of China | Year: 2010

A comprehensive analysis on the reported geological, geochronological and geochemical data of the Permian basaltic rocks in Tarim and the western section of the Central Asian orogenic belt (CAOB) indicates that the volume, petrography and their peaking activity at 275 Ma are correlated with those characteristics of other large igneous provinces (LIPs) in the world and we termed it as Bachu LIP. Elements and Sr-Nd isotopic compositions of the basalts in Tarim suggest that they may originate from partial melting of a long-term enriched lithospheric mantle at 60-80 km depth, while the mafic dykes and ultramafic-mafic intrusions in Tarim most possibly originated from asthospheric mantle (OIB-like). On the other hand, the basaltic rocks from the CAOB predominantly originated from partial melting of a subduction-released fluid (and/or melts) metasomatized lithospheric mantle involved with variable OIB-like basaltic magma addition, e.g., the high-Ti series basaltic rocks in southern Altaid and Eastern Tianshan areas. Thus based on geochemical data of major and trace elements, two different mantle domains can be divided within Bachu LIP, i.e., a long-term enriched Tarim domain and a subduction-metasomatized depleted CAOB domain. These two mantle domains have different metalogenesis types, i.e., the metalogenesis in Tarim is dominated by V-Ti magnetite mineralization, while in CAOB, dominated by Cu-Ni-PGE sulphide and co-genesis of Cu-Ni-PGE sulphide and V-Ti magnetite mineralization. The metallgenetic difference between in Tarim and in the western section of the CAOB is concurrent with the two different mantle domains. By integrating geological, geochronlogical, metallgenetic and geochemical data, we conclude that the formation of Bachu LIP is closely linked with a Permian mantle plume, which we term it as Bachu plume. Source

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