Oxygen Isotope Characteristics of the Footwall Alteration Zones in the Hongtoushan Volcanogenic Massive Sulfide Deposit,Liaoning Province,China and Restoration of Their Formation Temperatures  

作　　者：ZHENG Yuanchuan GU Lianxing TANG Xiaoqian LIU Sihai WU Changzhi LI Chunhai 

机构地区：[1]Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 10003 7, China [2]State Key Laboratory for Endogenic Metal Deposits Research （Nanjing University）,＂ Department of Earth Sciences, Nanjing University, Nanjing 210093, China

出　　处：《Acta Geologica Sinica(English Edition)》2011年第3期683-693,共11页地质学报（英文版）

基　　金：supported financially by the National Basic Research Program of the People's Republic of China (2006CB403501);the National Natural Science Foundation of China(Nos 40872050,40872064)

摘　　要：The Hongtoushan Volcanogenic Massive Sulphide Deposit（VMSD）occurs in the Hunbei granite-greenstone terrane,Liaoning Province,NE China.Rocks in the mining area have been metamorphosed around 3.0-2.8 Ga to upper amphibolite facies at temperatures between 600℃and 650℃.Cordierite-anthophyllite gneiss（CAG）in the Hongtoushan mining area,which occurs hundreds of meters below the ore horizon,corresponds to the metamorphosed semi-conformable alteration zone of the VMSD hydrothermal system,whereas the one immediately below the main ore layer represents the metamorphosed pipe-like alteration zone.Whole-rock oxygen isotope signatures were well preserved in both types of CAGs,although the mineral components have been entirely changed during regional metamorphism.Therefore,whole-rock oxygen isotopes can be used to estimate the formation temperature of both types of alteration zone.Calculations show that the semi-conformable and pipelike alteration zones for the Hongtoushan submarine hydrothermal system were formed at 290-360℃and 285-320°C,respectively,whereas estimates for the former were slightly higher than that of the latter,indicating that the semi-conformable alteration zone represents the deep part of the Hongtoushan seafloor hydrothermal system,while the pipe-like alteration zone represents the discharge conduits for metal-rich fluids,which is closer to the seafloor.The Hongtoushan Volcanogenic Massive Sulphide Deposit（VMSD）occurs in the Hunbei granite-greenstone terrane,Liaoning Province,NE China.Rocks in the mining area have been metamorphosed around 3.0-2.8 Ga to upper amphibolite facies at temperatures between 600℃and 650℃.Cordierite-anthophyllite gneiss（CAG）in the Hongtoushan mining area,which occurs hundreds of meters below the ore horizon,corresponds to the metamorphosed semi-conformable alteration zone of the VMSD hydrothermal system,whereas the one immediately below the main ore layer represents the metamorphosed pipe-like alteration zone.Whole-rock oxygen isotope signatures were well preserved in both types of CAGs,although the mineral components have been entirely changed during regional metamorphism.Therefore,whole-rock oxygen isotopes can be used to estimate the formation temperature of both types of alteration zone.Calculations show that the semi-conformable and pipelike alteration zones for the Hongtoushan submarine hydrothermal system were formed at 290-360℃and 285-320°C,respectively,whereas estimates for the former were slightly higher than that of the latter,indicating that the semi-conformable alteration zone represents the deep part of the Hongtoushan seafloor hydrothermal system,while the pipe-like alteration zone represents the discharge conduits for metal-rich fluids,which is closer to the seafloor.

关 键 词：oxygen isotope formation temperature VMSD footwall alteration zones Hongtoushan Liaoning Province 

分 类 号：P618.41[天文地球—矿床学] P588.3[天文地球—地质学]