Mineralization,Geochemistry and Zircon U-Pb Ages of the Paodaoling Porphyry Gold Deposit in the Guichi Region,Lower Yangtze Metallogenic Belt,Eastern China  

作　　者：DUAN Liu'an YANG Xiaoyong DENG Jianghong WANG Fangyue LEE Insung 

机构地区：[1]CAS Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, Hefei 230026, China [2]Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China [3]No. 7 Gold Geological Party of the Chinese People's Armed Police Force, Yantai 264004, Shandong, China [4]Laboratory for Marine Mineral Resourees, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, Shandong, China [5]Center of Deep Sea Research, Institute of Oceanography, Chinese Academy of Sciences, Qingdao 266071, Shandong, China [6]School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China [7]School of Earth and Environmental Sciences, Seoul National University, Seoul 151- 742, Korea

出　　处：《Acta Geologica Sinica(English Edition)》2018年第2期706-732,共27页地质学报（英文版）

基　　金：supported by the National Key R&D Program of China(No.2016YFC0600404);the National Natural Science Foundation of China(Grant Nos.41673040 and 41611540339);the Project of National Land Resource Science and Technology of Anhui Province(2014-K-4)

摘　　要：The newly discovered Paodaoling porphyry Au deposit from the Guichi region, Lower Yangtze River Metallogenic Belt （LYRB）, contains 〉35 tons of Au at an average grade of -1.7 g/t. It is a porphyry ＇Au-only＇ deposit, as revealed by current exploration in the depths, mostly above -400 m, which is quite uncommon among coeval porphyry mineralization along the LYRB. Additionally, there are also Cu-Au bearing porphyries and barren alkaline granitoids in the Paodaoling district. Zircon LA-ICP-MS U-Pb dating of the Cu-Au-bearing porphyries yield an age of 141-140 Ma, falling within the main magmatic stage of the LYRB, whereas the barren granites give an age of 125-120 Ma, coeval with the regional A- type granites. The Cu-Au-bearing porphyries are LILE-, LREE-enriched and HFSE-depleted, typical of arc magmatic affinities. The barren granites are HFSE-enriched, with lower LREE/HREE ratios and pronounced negative Eu anomalies. The Cu-Au-bearing porphyries in the Paodaoling district have high oxygen fugacities and high water content. Pyrite sulfur isotopes of the Paodaoling gold deposit indicate a magmatic-sedimentary mixed source for the ore-forming fluids. Based on the alteration and poly-metal zonation of the deepest exploration drill hole from the Paodaoling Au deposit, we propose that Cu ore bodies could lie at depth beneath the current Au ore bodies. The magmatism and associated Cu-Au mineralization of the Paodaoling district are likely to have formed in a subduction setting, during slab rollback of the paleo-Pacific plate.The newly discovered Paodaoling porphyry Au deposit from the Guichi region, Lower Yangtze River Metallogenic Belt （LYRB）, contains 〉35 tons of Au at an average grade of -1.7 g/t. It is a porphyry ＇Au-only＇ deposit, as revealed by current exploration in the depths, mostly above -400 m, which is quite uncommon among coeval porphyry mineralization along the LYRB. Additionally, there are also Cu-Au bearing porphyries and barren alkaline granitoids in the Paodaoling district. Zircon LA-ICP-MS U-Pb dating of the Cu-Au-bearing porphyries yield an age of 141-140 Ma, falling within the main magmatic stage of the LYRB, whereas the barren granites give an age of 125-120 Ma, coeval with the regional A- type granites. The Cu-Au-bearing porphyries are LILE-, LREE-enriched and HFSE-depleted, typical of arc magmatic affinities. The barren granites are HFSE-enriched, with lower LREE/HREE ratios and pronounced negative Eu anomalies. The Cu-Au-bearing porphyries in the Paodaoling district have high oxygen fugacities and high water content. Pyrite sulfur isotopes of the Paodaoling gold deposit indicate a magmatic-sedimentary mixed source for the ore-forming fluids. Based on the alteration and poly-metal zonation of the deepest exploration drill hole from the Paodaoling Au deposit, we propose that Cu ore bodies could lie at depth beneath the current Au ore bodies. The magmatism and associated Cu-Au mineralization of the Paodaoling district are likely to have formed in a subduction setting, during slab rollback of the paleo-Pacific plate.

关 键 词：zircon U-Pb dating porphyry Au deposit Lower Yangtze River metallogenic belt （LYRB） Paodaoling paleo-Pacific plate subduction 

分 类 号：P618.51[天文地球—矿床学] P597[天文地球—地质学]