Sediment core from beneath the Amery Ice Shelf, East Antarctica, suggests mid-Holocene ice-shelf retreat

Abstract

The stability of floating ice shelves is an important indicator of ocean circulation and ice-shelf mass balance. A sub–ice-shelf sediment core collected during the Austral summer of 2000–2001 from site AM02 (69°42.8′S, 72°38.4′E) on the Amery Ice Shelf, East Antarctica, contains a full and continuous record of glacial retreat. The AM02 core site is ∼80 km south of the floating ice shelf edge and contains a 0.5-m-thick Holocene surface layer of siliceous mud and diatom ooze of marine origin. Core data are supportive of sub–ice-shelf circulation models that predict the landward flow of oceanic water, and prove that the landward transport of hemipelagic sediments occurs beneath floating ice shelves over distances of at least ∼80 km. An increase in sea-ice–associated diatom deposition in the upper part of the Holocene suggests that a major retreat of the Amery Ice Shelf to at least 80 km landward of its present location may have occurred during the mid-Holocene climatic optimum.