Subduction-related hot spring-type gold mineralization in the central Tengchong block,southwestern China |
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| Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;2. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;3. Institute of Geology, China Earthquake Administration, Beijing 100029, China;1. State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China;2. State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;3. Beijing Research Institute of Uranium Geology, Beijing 100029, China;4. Wuhan Center, China Geological Survey, Wuhan 430205, China;5. No. 2 Geological Party, Bureau of Geology and Mineral Exploration and Development, Lhasa 850007, Tibet, China;1. Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;2. Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;3. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;4. Hainan Bureau of Geology, Haikou 570206, China;1. School of Earth Science and Geological Engineering, Sun Yat-sen University, 510 275 Guangzhou, PR China;2. Institute of Geology and Mineral Exploration, Lefkovrisi, 50100 Kozani, Greece;3. Dipartimento di Scienze della Terra, Università degli Studi di Milano, via S. Botticelli, 23-20133 Milano, Italy;4. Foundation for Research and Technology-Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), P.O. Box 1414, GR-26504 Rio-Patras, Greece;5. Department of Materials Science, University of Patras, GR-26504 Rio-Patras, Greece;1. Sciences de la Terre, Université du Québec à Chicoutimi, QC G7H 2B1, Canada;2. Department of Earth and Planetary Sciences, McGill University, QC H3A OE8, Canada;3. United States Geological Survey, Spokane Office, WA 99201, USA |
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| Abstract: | Numerous present-day hot springs and associated ancient Lianghe gold deposit occur in the central Tengchong block, SW China, associated with oceanic crust subduction. From the center outwards, the alteration zones in the hot spring of the Rehai consist of alunite and silica in a breccia zone, a kaolinite and illite zone, and a chlorite, illite, kaolinite zone. The gas phase in the hot spring is dominated by CO2 with δ13C ranging from ?4.5‰ to ?7.2‰. These features indicate a major magmatic origin of the hot spring gas. The 3He/4He ratios in the gas from central Tengchong vary from 1.56 to 5.88, approaching to those of the MORB. This is probably related to the ongoing subduction of the Indian plate beneath the Tengchong block. The hot spring waters in the central Tengchong block have much higher content of Au and other elements, e.g., Ag, As, Sb, and Tl, than other typical hot springs, such as Hasbrouck, Sulfer, etc. in the world. The hot springs with more mantle gas contribution and higher water temperature show more elevated Au contents, which implies that the metal in the hot spring was most likely contributed from the magmatic gas. The compiled D-O isotopes of the hot spring waters from previous studies suggest that they are primarily derived from meteoric water. A genetic model for the hot spring system in the central of Tengchong has been tentatively established. The gold-charged hot spring is genetically connected to an active magma chamber, which was produced by subduction of oceanic crust. The chamber is driving long-term surface meteoric circulation and constantly releasing magmatic volatiles enriched with metals. As hot spring water mixed with magmatic volatiles, causing decompression-boiling and forming hydraulic fractures to penetrate the roof of siliceous sinter, which induced the continuing metal deposition and formed the Lianghe hot spring. |
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| Keywords: | Hot springs Rehai Lianghe gold deposit Tengchong Oceanic subduction |
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