Leucogranite

Leucogranite is a light-colored, granitic, igneous rock with almost no dark minerals. Alaskite is a synonym.

Leucogranites have been reported from a variety of orogenies involving continental collisions. Examples include the Black Hills (Trans-Hudson orogeny of Proterozoic age), the Blue Ridge basement complex (Grenville orogeny of Proterozoic age), the Paleozoic Appalachian orogeny in Maine, and the currently active Himalayan orogeny. The leucogranite magmas are interpreted to have been derived by melting of pelitic rocks in the upper portions of thickened crust. These melts result following deformation and metamorphism, but the heat source is uncertain. Shear-heating associated with large shear zones in the crust has been proposed as the mechanism.