Genesis of the Zhengguang gold deposit in the Duobaoshan ore field,Heilongjiang Province,NE China: Constraints from geology,geochronology and S-Pb isotopic compositions |
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| Institution: | 1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, China;3. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China;4. Shenyang Survey, China Geological Survey, Shenyang 110000, China;5. Oil & Gas Survey, China Geological Survey, Beijing 100029, China;1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;3. Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA |
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| Abstract: | The Zhengguang gold deposit in the Duobaoshan ore field, hosted in volcanic rocks of the Middle Ordovician Duobaoshan Formation, is one of the largest gold deposits in the Northeastern Great Xing’an Range of the Central Asian Orogenic Belt (CAOB). The deposit comprises the No. I, II and III ore zones with a total resource exceeding 35 tonnes of Au, 100,000 tonnes of Zn and 100 tonnes of Ag. A genetic relationship between gold mineralization and concealed tonalite porphyry is inferred based on the characteristics of cryptoexplosive breccia and hydrothermal alteration indicative of porphyry-type and epithermal mineralization. Zircon LA-ICPMS U-Pb dating reveals that the tonalite porphyry was emplaced at 462.1 ± 1.8 Ma (Middle Ordovician). The δ34SV-CDT values of sulfide minerals range from ?3.0‰ to ?1.7‰ with an average of ?2.33‰, indicating that sulfur was mainly derived from a magmatic source. The Pb isotopic compositions (206Pb/204Pb ranging from 17.572 to 17.629, 207Pb/204Pb from 15.424 to 15.486, and 208Pb/204Pb from 37.206 to 37.418) suggest a major mantle component for Pb and, by inference, for other ore metals. Therefore, we suggest that the ore-forming elements in the Zhengguang gold deposit may be related to the mantle-sourced tonalite porphyry. On the basis of the geological characteristics and geochemical signatures documented in this study, we conclude that the Zhengguang gold deposit was formed in a porphyry to epithermal transitional environment associated with the concealed tonalite porphyry, as part of the Duobaoshan porphyry-epithermal ore system that is related to the subduction of the Paleo-Asian Ocean during the Ordovician. |
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| Keywords: | S-Pb isotopes Middle Ordovician Zhengguang gold deposit Duobaoshan Central Asian Orogenic Belt |
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