Glacial morphology and sediment formation in the Mertz Trough, East Antarctica

The Nathaniel B. Palmer 01-01 cruise produced a SeaBeam map showing unprecedented detail of the bathymetry in the Mertz Trough of East Antarctica. In addition, seismic reflection surveys and sediment core collection were completed in the region. The morphology of the Mertz Trough is combined with core data to interpret the sequence of events that occurred in this area since the Last Glacial Maximum. These complementary data indicate that an ice sheet once covered the Mertz Trough, which deposited diamicton and formed mega-scale glacial lineations during glacial maximal conditions and grounding-line wedges during recession. An erosional feature caused by subglacial meltwater breaching at least one of the grounding-line deposits is also recognized, along with a fan of sediment deposited seaward of the breach. Sediment cores from the Mertz Trough consist of two distinct units, the diamicton deposited subglacially and a diatom mud and ooze, deposited after the ice retreated. The latter unit has been preferentially deposited in deeper areas of the trough as a hemipelagic drape and shows that a change in the nature of the diatom unit occurred about 3300 14C yr BP.