How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Hill, N. J., Jenkin, G. R.T., Boyce, A. J. , Sangster, C. J.S., Catterall, D. J., Holwell, D. A., Naden, J. and Rice, C. M. (2015) How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland. Geological Society, London, Special Publications, 393(1), pp. 213-247. (doi: 10.1144/SP393.9)

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Abstract

The genesis of quartz vein-hosted gold mineralization in the Neoproterozoic–early Palaeozoic Dalradian Supergroup of Scotland remains controversial. An extensive new dataset of S-isotope analyses from the Tyndrum area, together with correlation of the global Neoproterozoic sedimentary S-isotope dataset to the Dalradian stratigraphy, demonstrates a mixed sedimentary and magmatic sulphur source for the mineralization. δ34S values for early molybdenite- and later gold-bearing mineralization range from −2 to +12‰, but show distinct populations related to mineralization type. Modelling of the relative input of magmatic and sedimentary sulphur into gold-bearing quartz veins with δ34S values of +12‰ indicates a maximum of 68% magmatic sulphur, and that S-rich, SEDEX-bearing, Easdale Subgroup metasedimentary rocks lying stratigraphically above the host rocks represent the only viable source of sedimentary sulphur in the Dalradian Supergroup. Consequently, the immediate host rocks were not a major source of sulphur to the mineralization, consistent with their low bulk sulphur and lack of metal enrichment. Recent structural models of the Tyndrum area suggest that Easdale Subgroup metasedimentary rocks, enriched in 34S, sulphur and metals, are repeated at depth owing to folding, and it is suggested that these are the most likely source of sedimentary sulphur, and possibly metals, for the ore fluids.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Boyce, Professor Adrian
Authors: Hill, N. J., Jenkin, G. R.T., Boyce, A. J., Sangster, C. J.S., Catterall, D. J., Holwell, D. A., Naden, J., and Rice, C. M.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Geological Society, London, Special Publications
Publisher:Geological Society
ISSN:0305-8719
ISSN (Online):2041-4927
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in Geological Society, London, Special Publications 393 (1):213-247
Publisher Policy:Reproduced under a Creative Commons License

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