The Laqiong Sb-Au deposit: Implications for polymetallic mineral systems in the Tethys-Himalayan zone of southern Tibet,China |
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| Institution: | 1. Chengdu Centre, China Geological Survey, Chengdu, Sichuan 610081, China;2. Key Laboratory of Tectonic Controls on Mineralisation and Hydrocarbon Accumulation of Ministry of Land and Resources, Chengdu University of Technology, Chengdu, Sichuan 610059, China;3. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China;5. Centre of Exploration Targeting, The University of Western Australia, 35 Stirling Highway, CRAWLEY, WA 6009, Australia;1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China;2. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China;3. Wuhan Institute of Geology and Mineral Resources, Wuhan, China;1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;2. Institute of Geological Survey, China University of Geosciences, Wuhan 430074, China;3. Petrochina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;1. Department of Resources Science and Engineering, Faculty of Earth Resources, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;2. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;3. John de Laeter Centre, TIGeR, Applied Geology, Curtin University, Bentley 6845, Australia |
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| Abstract: | The Himalayan mineral field includes over 50 quartz-vein type Sb-Au deposits, and placer Au deposits. The poorly documented Laqiong deposit is a typical example of quartz-vein type Sb-Au mineralisation in Tethys Himalayan sequence. The orebody are controlled by shallow north-dipping normal faults and north–south trending faults. Magmatic zircons extracted from muscovitic leucocratic granite from the southern part of the Laqiong mine area yield a Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry U-Pb age of 14 ± 1 Ma (n = 12, MSWD = 0.9) that is similar to the 40Ar/39Ar age of ca. 14 Ma from hydrothermal sericite in auriferous sulphide-quartz veins. The εHf(t) values for the magmatic zircon rims range from −5.4 to −1.9, corresponding to two-stage Hf model ages of 1403–1214 Ma. Quartz from the mineralised veins has δ18OH2O-SMOW values varying from +4.97 to +9.59‰ and δDH2O-SMOW values ranging from −119.7 to −108.1‰. The δ13CV-PDB values for calcite from the ore Stage III range from −6.9 to −5.3‰, and calcite from Stage IV are −3.5 to −1.7‰. The δ18OV-SMOW values for calcite from Stage III are +20.3 to +20.6‰ and for Stage IV are −6.3 to −4.9‰. The stibnite and pyrite samples have 208Pb/204Pb ratios of 38.158 to 39.02, 207Pb/204Pb ratios of 15.554 to 15.698, and 206Pb/204Pb ratios of 17.819 to 18.681, and bulk and in-situ δ34SV-CDT values for stibnite, arsenopyrite and pyrite range from −1.1 to +2.3‰. The calcite from the orebodies are enriched in MREE and depleted in LREE and HREE. Fieldwork, petrological, and geochemical data collected during our study leads to the following salient findings: the mineralising fluid is a mix of magmatic and meteoric fluids; and the deposit is closely related to the emplacement of Miocene granites originating from a thickened continental crust. |
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