JIA Qi1, FAN De-jiang1,2*, ZHANG Wen-qiang1, SUN Xiao-xia1, LIU Ming1, YANG Zuo-sheng1
(1. Key Lab of Submarine Geosciences and Technology of the Ministry of Education, Ocean University of China, Qingdao 266100, China;
2. Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China)
Abstract: Sulfides in surface sediments of hydrothermal field 49.6°E and 50.5°E in Southwestern Indian Ridge(SWIR) were studied with SEM and EPMA methods. Results show that sediments in the areas were impacted by hydrothermal activities, containing pyrite, sphalerite, chalcopyrite, isocubanite etc. Most of sulfide grains are euhedral or subhedral and preserved well. Among them, the crystal forms of pyrites are cubic, cubic-octahedron combinations; the dissolution porous structures are familiar with sphalerite and chalcopyrite. While exsolution structures appear in isocubanite. The type, particle structure and trace element characteristics of sulfide minerals indicate that sulfides in surface sediments of the 49.6°E field were the products of two hydrothermal mineralization stages at least. The early stage is associated with medium temperature mineralization; at its late stage, the sulfides formed in early stage were reworked by high temperature Fe-rich fluid. High temperature sulfides assemblage were found in surface sediments of the 50.5°E field.
Keywords: Southwestern Indian Ridge; sediment; sulfide; hydrothermal activity
ACTA MINERALOGICA SINICA Vol. 37, No. 6, 2017, Page 725-736
