Seawater signatures in the supracrustal Lewisian Complex, Scotland

Parnell, J., Boyce, A.J. and Næraa, T. (2022) Seawater signatures in the supracrustal Lewisian Complex, Scotland. Geological Magazine, 159(9), pp. 1638-1646. (doi: 10.1017/S0016756822000474)

Abstract

Marble in the supracrustal rocks of the Lewisian Complex, Tiree, includes chlorine-bearing amphiboles, chlorine-rich apatite, sulphur-rich scapolite, albite and phlogopite, all of which are regarded as evidence for evaporites in other metamorphosed sequences. Titanite yields U–Pb ages of ∼1.6 Ga, i.e. late Laxfordian, which excludes a younger imprint of sodium metasomatism. Traces of anhydrite, and isotopically heavy pyrite, also indicate deposition from seawater. Elsewhere in the Hebrides, tourmaline in Lewisian Complex marbles may represent seafloor exhalative deposits. Combined, the evidence suggests Lewisian Complex supracrustal marbles formed in an evaporative environment, like other Palaeoproterozoic successions across the North Atlantic region.

• Item Type: Articles
• Additional Information: The work was supported in part by UK Natural Environment Research Council grant NE/M010953/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Boyce, Professor Adrian
• Authors: Parnell, J., Boyce, A.J., and Næraa, T.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Geological Magazine
• Publisher: Cambridge University Press
• ISSN: 0016-7568
• ISSN (Online): 1469-5081
• Published Online: 02 June 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Geological Magazine 159(9):1638-1646
• Publisher Policy: Reproduced under a Creative Commons License