YE Jun1,2,3, SHI Xue-fa2, YANG Yao-min2, LIU Ji-hua2, ZHOU Guo-fu4, LI Nai-sheng2,5
(1.Institute of Oceanology , Chinese Academy of Sciences , Shandong, Qingdao 266071, China;
2. Key laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;
3. Graduate School of Chinese Academy of Sciences, Beijing 100039, China;
4. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
5. National Oceanographic Center, Qingdao 266063, China)
Abstract: SWIR 49.6ºE hydrothermal field is the first discovered active field on the Southwest Indian ridge (SWIR) by the Chinese R/V Da Yang Yi Hao in 2007, which followed the earlier discovery of strong hydrothermal plume anomalies along this section of the SWIR in 2005. In this study, the mineralogy and mineral chemistry of the sulfide from this field were carried out. There are two distinct ore types, Zn-rich sulfide and Fe-rich sulfide. The dissertation porous structures，“chalcopyrite disease”structures, lamellae exsolution structures, and homologous overgrow structures are extensive in the sulfide ores. According to the mineral composition, the ore minerals can be classified into Fe-S series, Zn-S series, Cu-Fe-S series, Cu-S series and native metal series (Au, Cu, W). Based on the characteristics of mineral in the sulfide samples, two mineralization stages have been identified.①Stage I, Zn-rich sulfide stage, the main mineral assemblages are sphalerite-pyrite-chalcopyrite and the temperature of ore-forming fluid is relatively low;②Stage II, Fe-rich sulfide stage, the main mineral assemblages are pyrite-marcasite-sphalerite, and the ore-forming temperature is relatively high. The sulfides formed in early stage have been reworked by the late stage fluid.
Key words: Southwest Indian Ridge; ultraslow spreading ridge; mineralogy; hydrothermal sulfide; mineralization
E-mail: xfshi@fio.org.cn
ACTA MINERALOGICA SINICA Vol. 31, No. 1, 2011, Page 17-29
