Recent geological processes in the Central Bransfield Basin (Western Antarctic Peninsula)

Abstract

Abstract Acoustic character of the near-surface geological features in the Central Bransfield Basin, located between the northwestern Antarctic Peninsula and the South Shetland Islands, are products of recent sedimentary, volcanic and oceanographic processes. A platform, between 250 and 750 m water depth, is characterized by a highly rough surface with prolonged and hyperbolic reflections, which are interpreted as a result of ice-sheet grounding that occurred during the last glacial advance and iceberg scouring. Locally, this surface is draped by thin, stratified sediments deposited from suspension during the present interglacial stage. The upper slope shows prolonged and hyperbolic reflections without subbottom returns that form an irregular surface resembling slide scars and slumped material. Futher downslope, sediments become stratified, and individual, chaotic or semi-transparent slump masses occur locally, within the eroded valleys and in inter-valley areas. Basin sediments are defined by stratified, semi-transparent and chaotic deposits that correspond to a variety of mass-transport, volcanic and oceanographic processes. Mass-transport and volcanic processes develop slump masses, turbidite deposits and volcanic edifices of varying characteristics. The activity of slope-parallel bottom currents builds sediment drifts between the volcanic edifices and the base of the Antarctic Peninsula slope.