Marie Byrd Land
Cenozoic volcanism in Marie Byrd Land is related to the West Antarctic Rift and has been explained by the activity of a mantle plume. This plume either underlies Marie Byrd Land and its volcanoes, or it rose to the surface before Antarctica separated from New Zealand during the middle Cretaceous and induced volcanism across the continental borderlands of the Southwest Pacific. In the latter theory, the Marie Byrd Land volcanism is caused by a remnant plume head underneath the continent. The basement crops out along the coast and consists of granitoids and metamorphic sediments left by a Devonian-Cretaceous volcanic arc.