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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

Information

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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References

Barnes, I. and O'Neil, J. R. (1971) Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements in the Coast Range of California. Geockim. Cosmochim. Ada, 35, 699–718.CrossRefGoogle Scholar
Berry, R. j. and Johnston, J. L. (1980) The Natural History of Shetland. Collins, London. Brewster, D. (1823) Account of native hydrate of magnesia, discovered by Dr Hibbert in Shetland. Trans. Roy. Soc. Edinburgh, 9, 239–42.Google Scholar
Clark, I. D. and Fontes, J-C. (1990) Paleoclimatic reconstruction in northern Oman based on carbonates from hyperalkaline ground waters. Quat. Res., 33, 320–36.CrossRefGoogle Scholar
Hoeg, O. A.(1929) Studies in stromatolites I. A postglacial marine stromatolite from southeastern Norway. K. Nor. Vidensk. Selsk. Skr., 1-60.Google Scholar
Hoppe, G. (1965) Submarine peat in the Shetland Islands. Geog. Ann. 47A, 195–203.CrossRefGoogle Scholar
Institute of Geological Sciences (1978) Regional Geochemical Atlas: Shetland. H.M.S.O. London.Google Scholar
Lippmann, F. (1973) Sedimentary Carbonate Minerals. Springer-Verlag, Berlin.CrossRefGoogle Scholar
Neal, C. and Stanger, G. (1983) Hydrogen generation from mantle source rocks in Oman. Earth Planet. Sci. Lett., 66, 169–76.CrossRefGoogle Scholar
O'Neil, J. R. and Barnes, I. (1971) C13 and O18 compositions in some fresh-water carbonates associated with ultramafic rocks and serpentinites: western United States. Geochim. Cosmochim. Ada, 35, 687–97.CrossRefGoogle Scholar
Pentecost, A. (1993) British travertines; a Review. Proc. Geol. Assoc, 104, 23–39.CrossRefGoogle Scholar
Pentecost, A. and Viles, H. C. (1994) A review and clarification of travertine classification. Geographic Physique et Quaternaire, (in press).Google Scholar
Thomas, C. H. (1980) Analysis of rock samples from the Shetland ophiolite belt. Report No. 113, Analytical Chemistry Unit, Institute of Geological Sciences.Google Scholar
Turi, B. (1986) Stable isotope geochemistry of travertines. In Handbook of Environmental Isotope Geochemistry, 2, (Fritz, P. and Fontes, J. Ch., eds.) 207-37.Google Scholar