Raman confirmation of microdiamond in the Svartberget Fe-Ti type garnet peridotite, Western Gneiss Region, Western Norway

Ultra-high pressure metamorphic rocks have been found worldwide. The volume and areal extent of an exhumed UHPM domain are important for understanding the geodynamic mechanisms responsible for the high pressure and relatively medium temperature conditions needed for their creation. We report here Raman microspectroscopical data that prove the existence of microdiamonds at the Svartberget Fe-Ti type peridotite locality in the Western Gneiss Region of Norway. Raman microscopy of two carbon microinclusions belonging to polyphase inclusion assemblages included in garnets from a garnet-phlogopite websterite vein yielded a sharp, narrow, intense peak at 1332 cm(-1), characteristic of diamond. The diamond is associated with polyphase solid inclusions possibly originating from supercritical, dense, H-C-N-O-F-P-S-Cl fluids. Lithological, textural and geochronological evidence points towards a Caledonian origin of the trapped fluid and subsequent diamond formation.