Seismic echo-characters and sedimentary distribution on the South Shetland Islands continental margin, Antarctica

The present work consists in characterizing the sedimentary distribution on the South Shetland Islands continental margin, Antarctica Peninsula, through the interpretation and correlation of high-resolution seismic profiles and geological samples. The characterization was made through echo-characters, maps of seismic amplitudes and its correlation with the collected samples, filling the gap in scientific research about echo-characters at this location. Five different echo types have been identified and classified. Echo types I and II have good seismic resolution and are characterized by continuous sharp bottom echoes with sub-parallel reflections. Echoes III and IV are characterized by difuse and very prolonged bottom echoes with no sub-bottom reflectors. Echo V is associated to glacial deposits on the upper slope in response to deglaciation and the transport of coarse grains in a muddy matrix and is characterized by diffraction hyperbolae. The echo-characters showed good correlation with geological samples collected along the Bransfield Strait and bays of the King George Island, but not completely with the amplitudes map. Echo I has medium-high amplitudes and the samples within its area of occurrence (AM-02 and AM-14) indicates silty sand and sandy silt, respectively. Echo II presents the lowest seismic amplitudes and the sample within its area (AM-17) shows a content of approximately 90% mud. Echos III and IV, located on the shallowest portions of South Shetland's continental margin, demonstrate medium-low amplitude values, and are related to samples AM-01 and AM-04, both classified as sandy-silt with approximately 35% of sand.