tonalite-trondhjemite-granodiorite /ˈtoʊnəlaɪt ˈtrɒn(d)jəmaɪt ˌɡrænəʊˈdaɪəraɪt/ noun1 •A group of silica-rich intrusive igneous rocks that mainly formed in Earth’s early history. They are considered some of the primary building blocks of the oldest continental crust and are typically produced by partial melting of hydrated basalt deep in the crust or mantle.
