What Supports the Marie Byrd Land Dome? An Evaluation of Potential Uplift Mechanisms in a Continental Rift System

Volcanism in the Marie Byrd Land (MBL) volcanic province is related to the growth of an 1200 × 500 km structural dome that lies on the Amundsen Sea coast. Spatial and temporal patterns of volcanic activity suggest that dome uplift began around 29–25 Ma and has continued to the present. Uplift has been accompanied by sometimes voluminous basaltic and felsic volcanism and the development of horst and graben structure, with a maximum of ∼3 km of uplift. Estimates of crustal thickness, based on models of gravity data and surface wave dispersion studies, have not resolved questions about the origin of uplift. Mantle plume activity has been proposed; but more detailed tomographic imaging of the mantle, together with seismic determinations of crustal thickness, and the thickness and distribution of sub-ice volcanic rock, are needed to test this, and to answer other petrologic and tectonic questions discussed below.