Garnet-bearing olivine-websterite within the Eastern Glenelg Lewisian of the Glenelg Inlier, NW Highlands

This paper documents the first identified occurrence of a garnet-bearing ol wivine-web-sterite rock within the Eastern Glenelg Lewisian of the Glenelg inlier. Bulk chemistries of the rock and associated websterites are compara ble with komatiite or ultrabasic intrusive rocks. However, comparison with zoned ultrabasic-basic gneisses from the Scourie area suggests that the roc k may be genetically linked to associated eclogites and represents a cumula te from a magma of basaltic composition. Geothermobarometry indicates that the rock equilibrated at eclogite facies P-T conditions: 20 +/- 3 kbar, 730 +/- 50 degreesC. It is suggested that the magmatic protolith for this rock was emplaced during the Scourian, and from the textural evidence of the py roxene grains, experienced granulite facies conditions followed by cooling prior to being subject to eclogite facies metamorphism during Grenville eve nts.