| Metallogenic Epoch of Nonferrous Metallic and Silver Deposits in the Jiaodong Peninsula, China and its Geological Significance |
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| 作者姓名： | SONG Mingchun WANG Shanshan YANG Lixin LI Jie LI Shiyong DING Zhengjiang |
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| 摘 要： | As China's most important gold-producing district,the Jiaodong Peninsula also contains copper,lead-zinc,molybdenum(tungsten),and other nonferrous metal ore deposits,but the space-time and genetic relationships with gold deposits remain uncertain.To investigate the temporal relationship between these nonferrous metal and gold ore deposits,We collected the samples from a number of nonferrous metallic and silver deposits and metallogenetic rock bodies in the eastern Jiaodong Peninsula for isotopic dating.The results show that the Re-Os isotopic model ages of the Lengjia molybdenum deposit in Rongcheng range from 114.5± 1.8 Ma to 112.6± 1.5 Ma,with an average age of 113.6± 1.6Ma;the LA-ICP-MS ~(206)Pb/~(238)U ages of 33 zircons in the sericitization porphyritic monzogranite that hosts the Tongjiazhuang silver deposit in Rongcheng range between 122 Ma and 109 Ma,with a weighted mean age of 116.04± 0.95 Ma;the LA-ICP-MS ~(206)Pb/~(238)U ages of 31 zircons in the copper metallogenic pyroxene monzodiorite that hosts the Kuangbei copper deposit in Rongcheng range from126 Ma to 106 Ma,with a weighted mean age of 116.6± 1.7 Ma;and the LA-ICP-MS ~(206)Pb/~(238)U ages of19 zircons in the pyroxene monzodiorite surrounding the Dadengge gold and multimetal deposit in Weihai range from 113 Ma to 110 Ma,with a weighted mean age of 111.7± 0.6 Ma.All these results indicate that the metallogenic ages of the silver and nonferrous metallic deposits in the Jiaodong Peninsula are in a limited range from 118 Ma to 111 Ma.Previous studies have demonstrated that the isotopic ages of gold deposits in the Jiaodong Peninsula range from 123 Ma to 110 Ma,while Weideshanian magmatism occurred between 126 Ma to 108 Ma.Both these ranges are grossly consistent with the metallogenic ages of silver and nonferrous metallic deposits in this study,suggesting that the large-scale mineralization occurred in the Early Cretaceous when magmatic activities were strong.This epoch may be linked to the lithosphere thinning and the thermo-upwelling extension in eastern China at that time.In addition,field investigation also shows that gold and nonferrous metallic deposits are distributed nearby the Weideshanian granite,with the nonferrous metallic deposits lying within or surrounding the granite pluton and the gold deposits outside the granite pluton.We propose the following mineralization scenario:In the Early Cretaceous,an intensive lithospheric extension induced partial melting and degassing of the metasomatized lithospheric mantle,which resulted in the formation of mantle-derived fluids enriched in metal elements.During the rapid process of magma ascent and intrusion,crust-derived fluids were activated by the magmatic thermal dome and served to further extract ore-forming materials from the crust.These fluids may have mixed with the mantle-derived fluid to form a crust-mantle mixing-type ore-forming fluid.The high-temperature conditions in the center or in contact with the granitic magmatic thermal dome would have been favorable for the formation of porphyry-type,skarn-type,and hydrothermal-vein-type ores,thus forming a series of Mo(W),Cu,and Pb-Zn deposits in the mid-eastern Jiaodong Peninsula.In contrast,the medium-to low-temperature conditions in the periphery of the magmatic thermal dome would have favored the deposition of gold(silver) ores under the appropriate physiochemical and structural conditions.The metallogenic epoch of the molybdenum,copper,and silver deposits,and their spatio-temporal and genetic relations to the gold deposits,as demonstrated in this study,not only provide important insights to the study of regional metallogeny,our understanding of the metallogenesis of the Jiaodong type gold deposit,and the geodynamic background of the large-scale mineralization in the Jiaodong Peninsula,but also have practical value in guiding the mineral exploration.
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| 收稿时间： | 2016/2/5 0:00:00 |
| 修稿时间： | 2016/6/22 0:00:00 |
Metallogenic Epoch of Nonferrous Metallic and Silver Deposits in the Jiaodong Peninsula, China and its Geological Significance |
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| Authors: | SONG Mingchun WANG Shanshan YANG Lixin LI Jie LI Shiyong and DING Zhengjiang |
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| Institution: | 1 Shandong Provincial Bureau of Geology & Mineral Resources, Jinan 250013, Shandong, China
2 Shandong Provincial Engineering Research Center for Geological Prospecting, Jinan 250013, Shandong, China,3 The Sixth Geology & Mineral Resources Survey Institute of Shandong Province, Weihai 264209, Shandong, China,3 The Sixth Geology & Mineral Resources Survey Institute of Shandong Province, Weihai 264209, Shandong, China,4 Department of Resource, Hebei University of Geosciences, Shijiazhuang 050000, Hebei, China,5 Geophysical & Geochemical Exploration Institute of Shandong Province, Jinan 250013, Shandong, China and 6 The Third Geology & Mineral Resources Survey Institute of Shandong Province, Yantai 264003, Shandong, China |
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| Abstract: | As China's most important gold‐producing district, the Jiaodong Peninsula also contains copper, lead–zinc, molybdenum (tungsten), and other nonferrous metal ore deposits, but the space–time and genetic relationships with gold deposits remain uncertain. To investigate the temporal relationship between these nonferrous metal and gold ore deposits, We collected the samples from a number of nonferrous metallic and silver deposits and metallogenetic rock bodies in the eastern Jiaodong Peninsula for isotopic dating. The results show that the Re‐Os isotopic model ages of the Lengjia molybdenum deposit in Rongcheng range from 114.5 ± 1.8 Ma to 112.6 ± 1.5 Ma, with an average age of 113.6 ± 1.6 Ma; the LA‐ICP‐MS 206Pb/238U ages of 33 zircons in the sericitization porphyritic monzogranite that hosts the Tongjiazhuang silver deposit in Rongcheng range between 122 Ma and 109 Ma, with a weighted mean age of 116.04 ± 0.95 Ma; the LA‐ICP‐MS 206Pb/238U ages of 31 zircons in the copper metallogenic pyroxene monzodiorite that hosts the Kuangbei copper deposit in Rongcheng range from 126 Ma to 106 Ma, with a weighted mean age of 116.6 ± 1.7 Ma; and the LA‐ICP‐MS 206Pb/238U ages of 19 zircons in the pyroxene monzodiorite surrounding the Dadengge gold and multimetal deposit in Weihai range from 113 Ma to 110 Ma, with a weighted mean age of 111.7 ± 0.6 Ma. All these results indicate that the metallogenic ages of the silver and nonferrous metallic deposits in the Jiaodong Peninsula are in a limited range from 118 Ma to 111 Ma. Previous studies have demonstrated that the isotopic ages of gold deposits in the Jiaodong Peninsula range from 123 Ma to 110 Ma, while Weideshanian magmatism occurred between 126 Ma to 108 Ma. Both these ranges are grossly consistent with the metallogenic ages of silver and nonferrous metallic deposits in this study, suggesting that the large–scale mineralization occurred in the Early Cretaceous when magmatic activities were strong. This epoch may be linked to the lithosphere thinning and the thermo‐upwelling extension in eastern China at that time. In addition, field investigation also shows that gold and nonferrous metallic deposits are distributed nearby the Weideshanian granite, with the nonferrous metallic deposits lying within or surrounding the granite pluton and the gold deposits outside the granite pluton. We propose the following mineralization scenario: In the Early Cretaceous, an intensive lithospheric extension induced partial melting and degassing of the metasomatized lithospheric mantle, which resulted in the formation of mantle–derived fluids enriched in metal elements. During the rapid process of magma ascent and intrusion, crust‐derived fluids were activated by the magmatic thermal dome and served to further extract ore‐forming materials from the crust. These fluids may have mixed with the mantle‐derived fluid to form a crust–mantle mixing–type ore‐forming fluid. The high‐temperature conditions in the center or in contact with the granitic magmatic thermal dome would have been favorable for the formation of porphyry–type, skarn–type, and hydrothermal–vein–type ores, thus forming a series of Mo(W), Cu, and Pb‐Zn deposits in the mid‐eastern Jiaodong Peninsula. In contrast, the medium‐ to low‐temperature conditions in the periphery of the magmatic thermal dome would have favored the deposition of gold (silver) ores under the appropriate physiochemical and structural conditions. The metallogenic epoch of the molybdenum, copper, and silver deposits, and their spatiot‐emporal and genetic relations to the gold deposits, as demonstrated in this study, not only provide important insights to the study of regional metallogeny, our understanding of the metallogenesis of the Jiaodong type gold deposit, and the geodynamic background of the large‐scale mineralization in the Jiaodong Peninsula, but also have practical value in guiding the mineral exploration. |
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| Keywords: | metallogenic epoch nonferrous metal mineral silver deposit thermal uplifting- extensional structure mineralization scenario Jiaodong type gold deposit |
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