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Zeng Q.-G.,CAS Guangzhou Institute of Geochemistry | Wang B.-D.,Regional Geological Survey Party | Wang B.-D.,Chengdu Institute of Geology and Mineral Resources Geological Survey | Qiangba Z.-X.,Regional Geological Survey Party | And 3 more authors.
Geological Bulletin of China | Year: 2010

The granitic gneiss was identified from the Jitang Group in the Leiwuqi area, eastern Tibet. All zircons from the granitic gneiss have shown regular oscillatory magmatic zoning and high Th/U ratios (≤ 0.49), being consistent with those of magmatic zircons. So we quoted 206Pb/238U ages to indicate crystallization age of the granitic magma. Analysis of Cameca zircon U-Pb isotope yielded a weighted mean 206Pb/238U age of 282.1 ± 0.9 Ma. The age of granitic gneiss implies that this magmatism event was triggered by the southwest subduction of the Lancangjiang suture in early Permian. In another word, magmatic growth in Lancangjiang suture had been taken place during early Permian.

Duan Z.,Chengdu Institute of Geology and Mineral Resources Geological Survey | Li G.,Chengdu Institute of Geology and Mineral Resources Geological Survey | Zhang H.,Chengdu Institute of Geology and Mineral Resources Geological Survey | Li Y.,Chengdu Institute of Geology and Mineral Resources Geological Survey | Duan Y.,China University of Geosciences
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2013

The Sena gold deposit recently discovered in Duolong metallogenic concentrated area is an epithermal gold deposit. There is few high-precision petrogenic and metallogenic geochronological data. The zircon U-Pb dating, the major elements, trace elements and zircon Sr-Nd isotopic data of the ore-hosting quartz monzobiorite in Sena deposit are reported in this paper. Weighted mean U-Pb age of the Zircon from the quartz monzobiorite, (122.0±1.8) Ma, can be regarded as the age of magmatic crystallization. The ore-hosting quartz monzobiorite in the Sena gold deposit is characterized by low SiO2 (57.26% to 58.88%), high Al2O3 (16.58% to 17.50%), high MgO (2.65% to 2.98%), (A/CNK)=0.93 to 1.09, rich in LREE (LREE/HREE=6.28 to 7.25), Eu=0.85 to 1.05, meanwhile by high Rb, U, La, Sr, Sm contents, coupled with low Nb, Ta, Zr, Hf contents. Compared with primary mantle, the quartz monzobiorite in Sena gold deposit has respectively high Sr [(87Sr/86Sr)i=0.705 023 to 0.705 453], low Nd[εNd(t)=-0.18 to 2.43]. The model age (TDM2=0.78 to 1.03 Ga) indicates that the quartz monzobiorite belongs to the over aluminum granite. Authors suggest that the Early Cretaceous magmatism and mineralization be caused by crystallization differentiation and contact metasomatism of parent magma which consist of partial melting materials, few sediments and mantle derived magma.

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