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Primitive olivine melanephelinite dykes from the Orkney Islands, Scotland

Published online by Cambridge University Press:  01 May 2009

B. G. J. Upton ,
R. H. Mitchell ,
A. Longs  and
P. Aspen
B. G. J. Upton
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, Edinburgh EH9 3JW, U.K.
R. H. Mitchell
Affiliation:
Department of Geology, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada
A. Longs
Affiliation:
Department of Geology, University of London, Royal Holloway and Bedford New College, Egham TW2O OEX, U.K.
P. Aspen
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, Edinburgh EH9 3JW, U.K.
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Abstract

Two suites of Permian dykes in the Orkney Islands consist of a predominantly ENE trending camptonite suite and a mainly N-to NE-trending suite formerly referred to as monchiquitic. Some of the silica-poor and more magnesium dykes in the latter suite can be more precisely defined as olivine melanephelinites. Within the parochial context of the British Isles, such compositions appear to be unique. The magmas are deduced to have been primitive, small-scale (? < 0.2%) partial melt products of the asthenospheric mantle that have experienced relatively little modification in transit through the lithosphere.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 3 , May 1992 , pp. 319 - 324
Copyright
Copyright © Cambridge University Press 1992

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