Meltwater features that suggest Miocene ice-sheet overriding of the Transantarctic Mountains in Victoria Land, Antarctica

We illustrate here spectacular meltwater features associated with outburst floods beneath an ice sheet that overrode the Transantarctic Mountains in southern Victoria Land. Because of long-term hyperarid polar climate, these features are part of an ancient landscape preserved for about 14 million years. Some channels are associated with areal scouring of basement rocks extending from sea level to as much as 1200-2100 m elevation in coastal regions. Scablands with scallops, potholes and plunge pools are cut in Beacon Super-group sandstones and Ferrar Dolerite and cover wide areas of high western plateaus near the mountain crest. Subglacial channel systems commonly originate near divides and converge downhill toward the northeast. We argue that the landforms were created beneath a major Antarctic Ice Sheet that submerged the whole area, with the possible exception of the high peaks of the Royal Society Range, as it flowed northeastward toward the outer Antarctic continental shelf. Areal scouring, associated with warm-based regimes, is restricted to the lower slopes close to the coast. In the higher terrain, meltwater channels and scabland alongside preserved patches of regolith are best explained by the breaching of cold-based ice on the mountain rim by subglacial meltwater outbursts. Melt from warm-based ice, along with subglacial lakes trapped upstream of the mountain rim, are possible sources of the meltwater necessary to form the channel systems and scablands.