Plutonic rocks of the eastern Bella Coola map area, southwest British Columbia

Abstract

The abundant plutonic rocks of the eastern Bella Coola map area are mostly of intermediate composition and are interpreted as Jurassic to Eocene. They are subdivided into five intrusive suites, one intrusive complex, and several undifferentiated plutons. The Salloomt suite ((?)Jurassic) is dominated by medium-grained, hornblende-rich diorite. The Kalone suite of biotite-hornblende tonalite is involved in ductile deformation within shear zones adjacent to Jump Across Creek. The Talcheazoone suite consists of uniformly foliated quartz diorite. The Firvale suite comprises altered Early Cretaceous biotite granodiorite. The Four Mile suite comprises pristine biotite-muscovite granite; these plutons truncate a regional pattern of the northwest-trending folds and shear zones. The Crag Creek intrusive complex is diorite and gabbro cut by numerous locally sheeted dykes of granodiorite, rhyolite, basalt, and andesite. Some lens-like sills between screens of country rock may have formed along pre-existing, subvertical structures.