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Disseminated sulphides in basalts from the northern central Indian ridge: Implications on late-stage hydrothermal activity

DRS at CSIR-National Institute of Oceanography

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Title Disseminated sulphides in basalts from the northern central Indian ridge: Implications on late-stage hydrothermal activity
 
Creator Banerjee, R.
Ray, D.
 
Subject GEOLOGY AND GEOPHYSICS
GEOLOGY AND GEOPHYSICS
 
Description This study examined the mineralogy and mineral chemistry of disseminated sulphides (mainly chalcopyrite-pyrite) in partly altered basalts from the northern Central Indian Ridge, Indian Ocean in order to understand the role of hydrothermal alterations and infer possible sulphide formation history. Pyrite and chalcopyrite are dominant sulphide minerals and generally associated with the oxide phases including magnetite and often ilmenite. Close association of sulphide and oxide minerals suggests that they are paragenetically related. Sulphides also occur as late impregnated veins cutting through the basaltic hosts. The chemical compositions of pyrite (avg. Fe 46.3 wt%, S 53.7 wt%) and chalcopyrite (avg. Cu 34.4 wt%, Fe 30.7 wt%, S 34.7 wt%) are almost uniform, while the secondary ilmenite often shows MnO enrichment (up to 3.0–3.4 wt%). The associated altered minerals typically resemble the greenschist facies mineral assemblages—e.g. chlorite±epidote. Evidence of albitisation and silicification suggests low-temperature hydrothermal alteration processes. This is supported by the bulk Au content (up to 60 ppb) of host-altered basalts with pyrite mineralisation. Au is usually associated with late-stage pyrites and thus related with low-temperature hydrothermal activity. Close to the dredge location, tectonic activity around the Vityaz megamullion might have promoted hydrothermal circulation and subsequent alteration of the mineral constituents in basalts, eventually inducing the formation of late-stage disseminated sulphide minerals in these rocks.
 
Date 2015-07-14T07:17:06Z
2015-07-14T07:17:06Z
2015
 
Type Journal Article
 
Identifier Geo-Marine Letters, vol.35(2); 2015; 91-103
http://drs.nio.org/drs/handle/2264/4743
 
Language en
 
Rights An edited version of this paper was published by Springer. This paper is for R & D purpose and Copyright [2014] Springer.
 
Publisher Springer