LI Bing 1,2,3, SHI Xue-fa 2, YANG Yao-min 4, YE Jun 2, FANG Xi-sheng 2
(1. Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
2. First Institute of Oceanography, KeyLaboratory of State Oceanic Administration for Marine Sedimentology & Environment Geology, Qingdao 266061, China;
3. University of Chines Academy of Sciences, Beijing 100049, China;
4. National Deep Sea Center, Qingdao 266061, China)
Abstract: The 14.0°S hydrothermal field in the southern mid-Atlantic ridge was first discovered by Chinese scientists and is located on the inside corner at the intersection of the southern mid-Atlantic ridge and the Cardno transform fault. In this paper, we conducted mineralogical studies on hydrothermal sulphides using transmission-reflection microscopy and X-ray diffraction (XRD). Hydrothermal sulphides occurring in this field can be divided into two categories according to their ore structures: massive sulphide ores and black chimney fragments. Massive sulphide ores can further be divided into iron sulphide ores and copper sulphide ores, while chimney fragments consist only of iron sulphide ores. However, according to the porosities which depend on the siliceous content, massive sulphide ores can also be divided into dense ores and porous ones. Microscopic studies of these sulphides suggest that hydrothermal activities in this field are characterized by multi-stages. Three stages were identified for these massive sulphide ores. These multi-stages are characterized by alternative development of sulphide and chert. Occurrence of a large amount of silica in surface stacking ores is probably related to development of a stock-work ore body within the crust. However, the general lack of Zn in surface stacking ores suggests that even though the hydrothermal system is consists of multiple stages, the remobilization of Zn within the hydrothermal system is not significant and probably resulted from the preferable crust permeability.
Keywords: 14.0°S hydrothermal field; hydrothermal sulfide; mental remobilization; crust permeability; stock-work ore body; the southern mid-Atlantic ridge
E-mail: bli@fio.org.cn
ACTA MINERALOGICA SINICA Vol. 35, No. 1, 2015, Page 35-43
