Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge

Wang, Yejian, Han, Xiqiu, Petersen, Sven, Jin, Xianglong, Qiu, Zhongyan and Zhu, Jihao (2014) Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge Marine Geology, 354 . pp. 69-80. DOI 10.1016/j.margeo.2014.05.003.

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Abstract

The Kairei hydrothermal field was the first confirmed active submarine hydrothermal system on the Central Indian Ridge. It has been suggested to be related to mafic as well as ultramafic host rocks based on vent fluid composition and the presence of ultramafic rocks in its vicinity. In this study, detailed geochemical and mineralogical analyses have been carried out on the hydrothermal precipitates from the Kairei vent field in order to investigate the possible presence of indications for an ultramafic substrate at this vent site. The studied samples included fragments of sulfide chimneys, massive sulfides and talc-bearing and silicified breccias. Three mineralization stages were identified: (1) a high-temperature stage consisting largely of chalcopyrite, isocubanite, and pyrite; (2) a medium to low temperature stage characterized by the mineral assemblages of sphalerite and pyrite; and (3) a weathering stage characterized by secondary Cu-sulfides (bornite, digenite, covellite and idaite), Fe-oxihydroxides, Opal-A, and Cu-chloride (paratacamite and atacamite). The sulfide geochemistry is characterized by high concentrations of Cu and Zn (Cu + Zn up to 29.3 wt.%, n = 17) and Au (mean 5.28 ppm, n = 17), which is comparable to results from seafloor massive sulfides collected from ultramafic-hosted sites in the Atlantic Ocean, but differs from those of typical mafic-hosted deposits. The high concentrations of Cu and Au at the Kairei hydrothermal field could be an indication for the involvement of ultramafic rocks in the subseafloor. Ultramafic-hosted, Au-rich sulfide deposits may not be restricted to the Atlantic Ocean and may be common along all slow- and intermediate-spreading ridges.

Document Type: Article
Keywords: hydrothermal precipitates; mineralization stages; ultramafic-hosted; Kairei hydrothermal field; Central Indian Ridge; RV Dayangyihao; DY105-17A cruise; DY115-19 cruise
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems > Marine Mineralische Rohstoffe
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1016/j.margeo.2014.05.003
ISSN: 0025-3227
Date Deposited: 10 Jun 2014 06:48
Last Modified: 23 Jun 2017 07:25
URI: http://eprints.uni-kiel.de/id/eprint/24706

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