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Travertine-cemented screes on the serpentinite seacliffs of Unst and Fetlar, Shetland

Published online by Cambridge University Press:  05 July 2018

Derek Flinn  and
Allan Pentecost
Derek Flinn
Affiliation:
Department of Earth Sciences, University of Liverpool, Brownlow Street, Liverpool L69 3BX, UK
Allan Pentecost
Affiliation:
Division of Life Sciences, Kings College London Campden Hill Road, London W8 7AH, UK
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Abstract

Screes on high serpentinite sea cliffs in Shetland have been internally cemented by deposits of brucite, hydromagnesite and aragonite since the last glaciation. These minerals have been deposited from solutions originating as rain (often contaminated with salt spray), which fell on the serpentinite screes and dissolved Mg and minor amounts of Ca from the more finely divided and powdery scree components. As the solutions filtered down through the screes they deposited cements in the form of spherulitic layers of brucite and hydromagnesite with minor amounts of aragonite. At sea level the Mg-rich solutions mingled with sea water impregnating the scree and there cementation within the scree took place by the crystallization of plush-type layers of aragonite on the serpentinite fragments.

Keywords

brucitehydromagnesitearagonitecalcitetravertineserpentiniteShetland
Type
Geochemistry
Information
Mineralogical Magazine , Volume 59 , Issue 395 , June 1995 , pp. 259 - 265
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

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