Travertine-Cemented Screes on the Serpentinite Seacliffs of Unst and Fetlar, Shetland

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

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: brucite • hydromagnesite • aragonite • calcite • travertine • serpentinite • Shetland

Mineralogical Magazine; June 1995 v. 59; no. 395; p. 259-265; DOI: 10.1180/minmag.1995.059.395.10
© 1995, The Mineralogical Society
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