Granodiorite

The dominant intruding rocks into the metamorphosed rocks of the Oban massif are granodiorites (Fig. 1).

Of the high-silica, coarse-grained, quartz-rich igneous rocks, granodiorites are quantitatively the most important.

Most of the rocks in the calc-alkaline association are granitoids, that is they are granites, granodiorites and tonalites all containing >20% quartz, with feldspar, mica and amphibole in various combinations (Chapter 3, Figures 3.10 and 3.11).