Distribution and solubility limits of trace elements in hydrothermal black smoker sulfides: An in-situ LA-ICP-MS study.

Wohlgemuth-Ueberwasser, Cora C., Viljoen, Fanus, Petersen, Sven and Vorster, Clarisa (2015) Distribution and solubility limits of trace elements in hydrothermal black smoker sulfides: An in-situ LA-ICP-MS study. Geochimica et Cosmochimica Acta, 159 . pp. 16-41. DOI 10.1016/j.gca.2015.03.020.

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Supplementary data:

Abstract

The key for understanding the trace metal inventory of currently explored VHMS deposits lies in the understanding of trace element distribution during the formation of these deposits on the seafloor. Recrystallization processes already occurring at the seafloor might liberate trace elements to later hydrothermal alteration and removement. To investigate the distribution and redistribution of trace elements we analyzed sulfide minerals from 27 black smoker samples derived from three different seafloor hydrothermal fields: the ultramafic-hosted Logatchev hydrothermal field on the Mid-Atlantic Ridge, the basaltic-hosted Turtle Pits field on the mid-atlantic ridge, and the felsic-hosted PACMANUS field in the Manus basin (Papua New Guinea). The sulfide samples were analyzed by mineral liberation analyser for the modal abundances of sulfide minerals, by electron microprobe for major elements and by laser ablation-inductively coupled plasma-mass spectrometry for As, Sb, Se, Te, and Au. The samples consist predominantly of chalcopyrite, sphalerite, pyrite, galena and minor isocubanite as well as inclusions of tetrahedrite–tennantite. Laser ablation spectra were used to evaluate the solubility limits of trace elements in different sulfide minerals at different textures. The solubility of As, Sb, and Au in pyrite decreases with increasing degree of recrystallization. When solubility limits are reached these elements occur as inclusions in the different sulfide phases or they are expelled from the mineral phase. Most ancient VHMS deposits represent felsic or bimodal felsic compositions. Samples from the felsic-hosted PACMANUS hydrothermal field at the Pual ridge (Papua New Guinea) show high concentrations of Pb, As, Sb, Bi, Hg, and Te, which is likely the result of an additional trace element contribution derived from magmatic volatiles. Co-precipitating pyrite and chalcopyrite are characterized by equal contents of Te, while chalcopyrite that replaced pyrite (presumably during black smoker growth) is enriched in Te relative to pyrite. These higher Te concentrations may be related to higher fluid temperature.

Document Type: Article
Additional Information: WOS:000354878700002
Keywords: Laser ablation, seafloor massive sulfides, black smoker, trace element geochemistry, Pacmanus, Logatchev, Turtle Pits
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS > Marine Mineralische Rohstoffe
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.gca.2015.03.020
ISSN: 0016-7037
Date Deposited: 22 Apr 2015 09:48
Last Modified: 19 Jun 2017 09:34
URI: http://oceanrep.geomar.de/id/eprint/28613

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