Seawater signatures in the supracrustal Lewisian Complex, Scotland

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....

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Bibliographic Details
Published in:Geological Magazine
Main Authors: Parnell, J., Boyce, A. J., Næraa, T.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press 2022
Subjects:
Geology
evaporites
Lewisian
marble
Palaeoproterozoic
scapolite
Scotland
Tiree
titanite
North Atlantic
Online Access:https://lup.lub.lu.se/record/d2d33381-2955-4e39-b1d5-257a21c6e1a6
https://doi.org/10.1017/S0016756822000474
Description
Summary: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.

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