Seawater signatures in the supracrustal Lewisian Complex, Scotland

John Parnell; Adrian J. Boyce; T Næraa

doi:10.1017/S0016756822000474

Seawater signatures in the supracrustal Lewisian Complex, Scotland

John Parnell^* (Corresponding Author), Adrian J. Boyce, T Næraa

^*Corresponding author for this work

Geology and Geophysics

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

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 similar to 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.

Original language	English
Pages (from-to)	1638 - 1646
Number of pages	9
Journal	Geological Magazine
Volume	159
Issue number	9
Early online date	2 Jun 2022
DOIs	https://doi.org/10.1017/S0016756822000474
Publication status	Published - 1 Sept 2022

Bibliographical note

J. Bowie, C. Brolly, J. Armstrong and J. Johnston provided skilled technical support. Electron microscopy was performed with the help of J. Still in the ACEMAC Facility at the University of Aberdeen. Scapolite was analysed on a sample from the Hunterian Museum, Glasgow (no. 134720), loaned courtesy of J. Faithfull. The work was supported in part by UK Natural Environment Research Council grant NE/M010953/1. Careful review by A.A. Cabral helped to improve the manuscript.

Data Availability Statement

Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.1017/S0016756822000474

Keywords

Lewisian
RICH SCAPOLITE
scapolite
ROCKS
Scotland
Tiree
DEPOSIT
Palaeoproterozoic
evaporites
GEOCHRONOLOGY
marble
EVOLUTION
FLUID INCLUSION
MINERALIZATION
EVAPORITE
ISOTOPE
titanite
METASOMATISM

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10.1017/S0016756822000474Licence: CC BY

Parnell_etal_GM_Seawater_Signatures_In_VoR
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Final published version, 972 KBLicence: CC BY

Cite this

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title = "Seawater signatures in the supracrustal Lewisian Complex, Scotland",

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 similar to 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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author = "John Parnell and Boyce, {Adrian J.} and T N{\ae}raa",

note = "J. Bowie, C. Brolly, J. Armstrong and J. Johnston provided skilled technical support. Electron microscopy was performed with the help of J. Still in the ACEMAC Facility at the University of Aberdeen. Scapolite was analysed on a sample from the Hunterian Museum, Glasgow (no. 134720), loaned courtesy of J. Faithfull. The work was supported in part by UK Natural Environment Research Council grant NE/M010953/1. Careful review by A.A. Cabral helped to improve the manuscript.",

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N2 - 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 similar to 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.

AB - 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 similar to 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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Seawater signatures in the supracrustal Lewisian Complex, Scotland

Abstract

Bibliographical note

Data Availability Statement

Keywords

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