Keele Research Repository

The 'Scourie Dyke' Suite of the North-West mainland Lewisian of Scotland - with particular reference to the structural geology and geochemistry.
The 'Scourie Dykes' were intruded into Scourian gneisses about 1,900 million years ago and were subsequently deformed and metamorphosed about 1,750 million years ago during the Laxfordian orogeny.
The intrusive relationships of the dykes and the deformation styles they show in reworked areas are described for a number of areas between Durness and Loch Torridon. An attempt is made to correlate the deformational and metamorphic episodes that have affected the dykes. The igneous and metamorphic petrology and geochemistry of the different dyke types are described and used to propose a scheme for their evolution.
The density of dyke outcrop in the Lewisian has been measured and the results plotted as contour maps. These maps show that dyke material is concentrated in parallel, NW-SE trending belts perpendicular to the crustal extension. The spacing of the belts is thought to give an indication of the variationin thickness of the crust 1,900 million years ago.