Hainan, China
Hainan, China

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Yu J.-J.,Chinese Academy of Geological Sciences | Chen F.-X.,Hainan Mining United Co. | Wang Y.-H.,Hainan Mining United Co. | Liang J.,Hainan Mining United Co. | Che L.-R.,China University of Geosciences
Geology in China | Year: 2012

The Indosinian granites in the periphery of the Shilu iron deposit belong to the Changjiang granitic body. These granites are mainly monzonitic granites. They lie between metaluminous field and weakly peraluminous field, and belong to high-K cale-alkaline series and shoshonitic series. The granites have ΣREE values of 134.96-241,05 ppm and show relatively strong enrichment of light rare earth elements (LREE/HREE= 4.44-9.67), with higher (La/Yb) N ratios of 3.95-10.69 and negative Eu anomalies ( δ Eu=0.28-0.57). Mandenormalized trace element spidergrams of all samples show obvious negative anomalies of Ba, Nb, Ta, Ce, Sr, P and Ti. The obvious negative Ba, Sr and Eu anomalies indicate that plagjoclase existed in the source region or the granites experienced plagioclase crystallization and fractionation. The granites have a range of (87SrZ86Sr)1 from 0.710852 to 0.715492 except for one sample (SL10-136) whose ( 87SrZ86Sr)1Value is 0.706364 , a narrow ε Na(t) value range of -7.3 to -9.1 and TDM2 model ages of 1.5 - 1.9 Ga, indicating a homogeneous source and partial melting of the Mid -Proterozoic Baoban Group. The granites were formed in a post -orogenic environment. Based on previous investigation of granite in Hainan Ireland, this paper deals with ireland-arc, syn-orogenic and post-orogenic granitoids in Hainan Ireland. The Hercynian to Indosinian granitoids can be compared with granitoids in northern Vietnam.

Yu J.,Chinese Academy of Geological Sciences | Mao J.,Chinese Academy of Geological Sciences | Chen F.,Hainan Mining United Co. | Wang Y.,Hainan Mining United Co. | And 3 more authors.
Ore Geology Reviews | Year: 2014

The Shilu deposit is a world-class Fe-Co-Cu orebody located in the Changjiang area of the western part of Hainan Island, South China. The distribution of Fe, Co, and Cu orebodies is controlled by strata of the No. 6 Formation in the Shilu Group and the Beiyi synclinorium. Based on a petrological study of the host rocks and their alteration assemblages, and textural and structural features of the ores, four mineralization stages have been identified: (1) the sedimentary ore-forming period; (2) the metamorphic ore-forming period; (3) the hydrothermal mineralization comprising the skarn and quartz-sulfide stage; and (4) the supergene period. The fluid inclusions in sedimentary quartz and/or chert indicate low temperatures (ca. 160°C) and low salinities from 0.7 to 3.1wt.% NaCleq, which corresponds to densities of 0.77 to 0.93g/cm3. CO2-bearing or carbonic inclusions have been interpreted to result from regional metamorphism. Homogenization temperatures of fluid inclusions for the skarn stage have a wide range from 148°C to 497°C and the salinities of the fluid inclusions range from 1.2 to 22.3wt.% NaCleq, which corresponds to densities from 0.56 to 0.94g/cm3. Fluid inclusions of the quartz-sulfide stage yield homogenization temperatures of 151-356°C and salinities from 0.9 to 8.1wt.% NaCleq, which equates to fluid densities from 0.63 to 0.96g/cm3.Sulfur isotopic compositions indicate that sulfur of the sedimentary anhydrite and Co-bearing pyrite, and the quartz-sulfide stage, was derived from seawater sulfate and thermochemical sulfate reduction of dissolved anhydrite at temperatures of 200. °C and 300. °C, respectively. H and O isotopic compositions of the skarn and quartz-sulfide stage demonstrate that the ore-forming fluids were largely derived from magmatic water, with minor inputs from metamorphic or meteoric water. The Shilu iron ore deposit has an exhalative sedimentary origin, but has been overprinted by regional deformation and metamorphism. The Shilu Co-Cu deposit has a hydrothermal origin and is temporally and genetically associated with Indosinian granitoid rocks. © 2013 Elsevier B.V.

Xu D.-R.,CAS Guangzhou Institute of Geochemistry | Wu J.,CAS Guangzhou Institute of Geochemistry | Wu J.,University of Chinese Academy of Sciences | Xiao Y.,Hainan Bureau of Geology and Exploration | And 6 more authors.
Geological Bulletin of China | Year: 2011

Shilu iron ore deposit, which is situated at the western Hainan Province of southern China, has been reputed as the biggest hematite-rich ore deposit in Asia. The formation and location of the deposit have close relationship with folds and their incidental shear and plastic flow structures. Based on tectonic styles and deformation mechanism of the orebodies and their host rocks, the strongly structural deformation in the studied ore deposit can be classified into two phases, which are D1, the early regional-scale synclinorium formation stage and D2, the late fold superimposition and concomitant shear deformation stage. The latter (D2) can be further divided into three uninterrupted stages of D2a, D2b and D2c, and represents dynamic transformation from ductile-brittle shear and high-T (temperature) plastic flow to low-T brittle fracture. The ore-bodies are strictly controlled by the NW-SW trending synclinorium and the superposed folds which were formed due to superposition of the late NE-NNE trending transversal folds on the early synclinorium, whereas the ductile-brittle shear and concomitant high-T plastic flow were main mechanisms for formation of the hematiterich ore-bodies. Iron-rich ore bodies in the Shilu iron ore deposit often can be found along the synclinorium axis, especially in the positions of the forementioned superposed synclines.

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