Formation, remobilisation and alteration processes at inactive hydrothermal vents: insights from elemental analysis of Cu-(Fe-)S sulfides from TAG, Mid-Atlantic Ridge
Formation, remobilisation and alteration processes at inactive hydrothermal vents: insights from elemental analysis of Cu-(Fe-)S sulfides from TAG, Mid-Atlantic Ridge
Chalcopyrite is the main Cu mineral in mafic-hosted marine hydrothermal systems. Its trace element budget and that of its alteration products may hold valuable information on formation, remobilisation and alteration processes of the hydrothermal system. In this study, we analysed chalcopyrite from five inactive seafloor massive sulfide (SMS) sites from the TAG hydrothermal field on the Mid-Atlantic Ridge by electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 24 elements. Twelve of them are discussed in detail. In general, trace element concentrations range between sub-parts per million (ppm) to several hundreds of ppm. The elements Se and Co are incorporated into the lattice at high temperatures of > 300 °C, whereas As, Ge, Ga substitute into the structure at intermediate to low temperatures. Other elements, e.g. Zn, are either accommodated into the mineral lattice or form inclusions, whereas V and Mn, which originate from seawater, get adsorbed onto the mineral surface. Idaite, chalcocite, and covellite exhibit similar trace element patterns to those of the precursor chalcopyrite. However, the secondary copper minerals show enrichment of Ag and Mo. Factors controlling the incorporation are predominantly related to changes in physicochemical conditions with the host rock composition playing only a minor role.
LA-ICP-MS, Seafloor massive sulfides, TAG hydrothermal field, Trace elements
1431-1448
Lehrmann, Berit
3a90a549-fcd6-4b5e-b361-7d31130d7a2f
Cooper, Matthew J.
54f7bff0-1f8c-4835-8358-71eef8529e7a
Milton, J. Andy
9e183221-d0d4-4ddb-aeba-0fdde9d31230
Murton, Bramley J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12
November 2022
Lehrmann, Berit
3a90a549-fcd6-4b5e-b361-7d31130d7a2f
Cooper, Matthew J.
54f7bff0-1f8c-4835-8358-71eef8529e7a
Milton, J. Andy
9e183221-d0d4-4ddb-aeba-0fdde9d31230
Murton, Bramley J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12
Lehrmann, Berit, Cooper, Matthew J., Milton, J. Andy and Murton, Bramley J.
(2022)
Formation, remobilisation and alteration processes at inactive hydrothermal vents: insights from elemental analysis of Cu-(Fe-)S sulfides from TAG, Mid-Atlantic Ridge.
Mineralium Deposita, 57 (8), .
(doi:10.1007/s00126-022-01106-2).
Abstract
Chalcopyrite is the main Cu mineral in mafic-hosted marine hydrothermal systems. Its trace element budget and that of its alteration products may hold valuable information on formation, remobilisation and alteration processes of the hydrothermal system. In this study, we analysed chalcopyrite from five inactive seafloor massive sulfide (SMS) sites from the TAG hydrothermal field on the Mid-Atlantic Ridge by electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 24 elements. Twelve of them are discussed in detail. In general, trace element concentrations range between sub-parts per million (ppm) to several hundreds of ppm. The elements Se and Co are incorporated into the lattice at high temperatures of > 300 °C, whereas As, Ge, Ga substitute into the structure at intermediate to low temperatures. Other elements, e.g. Zn, are either accommodated into the mineral lattice or form inclusions, whereas V and Mn, which originate from seawater, get adsorbed onto the mineral surface. Idaite, chalcocite, and covellite exhibit similar trace element patterns to those of the precursor chalcopyrite. However, the secondary copper minerals show enrichment of Ag and Mo. Factors controlling the incorporation are predominantly related to changes in physicochemical conditions with the host rock composition playing only a minor role.
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Submitted date: 15 December 2020
Accepted/In Press date: 16 March 2022
e-pub ahead of print date: 27 April 2022
Published date: November 2022
Additional Information:
Funding Information:
This study was funded by a grant from the European Union Seventh Framework Program (EU-FP7) “Blue Mining: breakthrough solutions for the sustainable deep-sea mining value chain” under grant No. 604500. The grant also supported the cruise on the NERC ship RRS James Cook (JC138) in 2016.
Publisher Copyright: © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Funding Information:
We wish to thank the officers and crew of RRS James Cook and the shipboard technical party for their professionalism and constant support during expedition JC138. Thanks also to D. Doran and M. Beverley-Smith (University of Southampton), D. Muir (Cardiff University) and C. Hayward (University of Edinburgh) for section preparation and technical support of the SEM and EPMA. Helpful comments by two anonymous reviewers and A.E. Cabral are gratefully acknowledged. We also wish to extend our thanks and appreciation to editor-in-chief Georges Beaudoin.
Keywords:
LA-ICP-MS, Seafloor massive sulfides, TAG hydrothermal field, Trace elements
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Local EPrints ID: 457170
URI: http://eprints.soton.ac.uk/id/eprint/457170
ISSN: 0026-4598
PURE UUID: 379ef5a3-cda2-41c7-bb7b-2e364c0d2993
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Date deposited: 25 May 2022 16:55
Last modified: 17 Mar 2024 07:17
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Author:
Berit Lehrmann
Author:
Bramley J. Murton
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