An Aillikite Dyke From Sutherland, Scotland

Faithfull, J. , Hughes, J., Upton, B.J.G., Ellam, R. and Ntaflos, T. (2014) An Aillikite Dyke From Sutherland, Scotland. In: Volcanic and Magmatic Studies Group Annual Meeting 2014, Edinburgh, Scotland, 6-8 Jan 2014,

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A 0.2 to 1m thick ESE-WNW aillikite dyke cuts Moine psammites a few km east of the Moine Thrust, in Glen Golly, Sutherland. While such rocks are known in Greenland, Labrador and Finland (where they are associated with diamond and/or REE carbonatite exploration targets), they have not been reported from the UK. The dyke is exposed in several outcrops over a length of at least 250m. It is composite, and shows considerable internal variation in mineralogy and texture, from carbonate-poor lithologies with fresh olivine macrocrysts, to silico-carbonatite. Major phases are macrocrystal olivine, phlogopite (zoned to Al, Ti-poor tetraferriphlogopite), apatite, magnesiochromite-magnetite spinels, carbonate, and a perovskite-like phase. Small xenoliths of spinel lherzolites occur, with pale aluminous spinels. Adjacent psammites show fenitization, with development of amphibole and biotite. Sr and Nd isotopes suggest source mantle similarities to those recorded in the younger Streap Comhlaidh and Loch Roag dykes of NW Scotland. Phlogopite from the dyke has given an Ar-Ar plateau age of 357+- 7Ma, which does not match any currently reported dates for similar rocks from Greenland or Labrador, or for any Scottish mafic alkaline minor intrusions, but may suggest an association with the early Carboniferous Birrenswark lavas in the Scottish Borders, and perhaps with altered ultramafic/carbonate-rich rocks reported from western Ireland.

Item Type:Conference Proceedings
Keywords:Ultramafic lamprophyre, mantle xenoliths
Glasgow Author(s) Enlighten ID:Ellam, Professor Rob and Faithfull, Dr John
Authors: Faithfull, J., Hughes, J., Upton, B.J.G., Ellam, R., and Ntaflos, T.
Subjects:Q Science > QE Geology
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
University Services > Library and Collection Services > Museum and Art Gallery
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