A Raman study of detrital Cr-spinels and their melt inclusions: Is Raman spectroscopy effective in determining their provenance?

About 150 detrital Cr-spinels from the Bovec and Bohinj Cretaceous flysch basins (Southern Alps, Slovenia) have been analyzed via Raman spectroscopy to verify if such technique can be effective in determining their provenance. Because one of the most used diagrams for assigning the provenance of Cr-spinels is the Cr/(Cr+Al) [Cr#] vs. Mg/(Mg+Fe2+) [Mg#] diagram, we relate these parameters to the Raman peaks. The correlation between the Cr# and the A1g peak position is about 0.93, increasing to 0.95 for Cr-spinels with Cr# lower than 0.5. Unfortunately, the Mg# correlation is only about 0.70 for the whole dataset but increases to 0.82 for spinels with Cr# lower than 0.5. Such correlation allows to recognize Cr-spinels from lherzolite and/or abyssal peridotite and distinguishing them from harzburgite, layered intrusions, Uralo-Alaskan complexes. Many of the present spinels are characterized by several inclusions. By using spot analyses and 3D Raman mapping on such inclusions we were able to recognize pyroxene–, feldspar– and amphibole–like inclusions, better constraining the provenance of the spinels.