首页|Timing and Tectonic Setting of the Gaoaobei Tungsten-Molybdenum Deposit in Nanling Range, South China
Timing and Tectonic Setting of the Gaoaobei Tungsten-Molybdenum Deposit in Nanling Range, South China
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The Gaoaobei tungsten-molybdenum deposit is a newly discovered large-scale quartz-vein-type deposit in the Nanling metallogenic belt in South China. The ore bodies are hosted in the In-dosinian granites and the Cambrian Xiangnan Group slates and are controlled by NWW-oriented faults, which are obviously different from the "five-story building" model in southern Jiangxi Province. The magmatic rocks in the study area are dominated by medium- to coarse-grained biotite monzogran-ite, with a few NW-oriented fine-grained granite dykes. The medium- to coarse-grained biotite monzo-granite and fine-grained granite dykes have zircon U-Pb ages of 229.4 ± 1. 9 Ma (MSWD = 1.5) and 164.9 ± 3.3 Ma (MSWD = 0.75), respectively, corresponding to the Indosinian and Yanshanian magma-tism. The monzogranites have higher contents of FeO, CaO, K2O, P2O5, and TiO2, while the granite dykes have slightly higher contents of SiO2, Al2O3, MnO, and Na2O. Their A/CNK values are 1.11-1.75 and 1.19-2.25, and the contents of CIPW normative corundum are 1.71％-6.66％ and 2.41％-9.50％, suggesting both the monzogranites and granite dykes are S-type granite. The total amount of rare earth elements in the monzogranites (from 84.7 ppm to 129 ppm) is slightly lower than that in the gran-ite dykes (from 128 ppm to 133 ppm). The Eu/Eu* values range from 0.12 to 0.30 in monzogranites and from 0.0011 to 0.0013 in granite dykes, indicating the fine-grained granites underwent more intense fractional crystallization. The monzogranite and granite dykes have high 87Sr/86Sri values of 0.7169-0.7193 and 0.72825-0.72880, low εNd(t) values ranging from -10.2 to -9.6 and from -11.5 to -11.4, and TDM2 ages of 1835-1785 and 1957-1946 Ma, respectively. These isotope data indicate their origin from the remelting of the Paleoproterozoic crustal materials. Combined with regional geology, it is conclud-ed that the medium- to coarse-grained biotite monzogranite was formed in a post-collisional extension-al environment. In addition, 40Ar-39Ar dating of the greisen type tungsten-molybdenum ore gave consis-tent plateau age of 164.0 ± 1.2 Ma, isochronal age of 162.0 ± 2.4 Ma and anti-isochronal age of 161.4 ± 1.8 Ma. Combined with the published molybdenite Re-Os age, the Gaoaobei tungsten-molybdenum de-posit was formed at ～164 Ma, which is inferred to be genetically related to the contemporaneous fine-grained granite dykes (165 Ma). The deposit was likely formed during the large-scale magmatism and mineralization event in the early Yanshanian of the Nanling Range in an intra-continental extensional environment caused by the subduction of the paleo-Pacific plate. The late and small granite dykes with-in the large granite plutons thus require further attention during mineral prospecting in the regions.
zirconU-Pb age40Ar-39Ar agegeochemistrytungsten molybdenum depositGaoaobeiNanling Range
Jianfeng Li、Kemeng Ma、Youyue Lu、Jianming Fu、Shunbo Cheng、Yuan Li、Chuanbiao Li
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College of Geographical Science, Liaoning Normal University, Dalian 116029, China
Wuhan Center of Geological Survey, China Geological Survey, Wuhan 430205, China
Granite Diagenesis and Mineralization Geology Research Center, China Geological Survey, Wuhan 430205, China
Mineral Resources Survey Institute of Hunan Province, Changsha 410083, China
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China Geological SurveyChina Geological SurveyChina Geological SurveyChina Geological Survey
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