The Gebra-Magia Complex: A submarine slope failure system in the Central Bransfield Basin (Antarctica)

• Main Authors: Casas, David, García, Marga, Bohoyo, Fernando, Maldonado, Andrés, Ercilla, Gemma
• Format: Conference Object
• Language: unknown
• Published: Scientific Committee on Antarctic Research 2018
• Subjects: Bransfield Basin; Submarine slope failure; Morphology; Depositional architecture; Antarctic; Antarctic Peninsula; Antarc*; Antarctica; SCAR; Scientific Committee on Antarctic Research
• Online Access: http://hdl.handle.net/10261/193229

IX Simposio de Estudios Polares del Comité Español del Scientific Committee on Antarctic Research (SCAR), 5-7 September 2018, Madrid, España.-- 1 page The Gebra-Magia Complex is an important example of a submarine mass-movement composite located on the lower continental slope of the NE Antarctic Peninsula (Central Bransfield Basin). Continuous instability dynamics over time is inferred to have affected the palaeo-trough mouth fans present in the study area. The combined analysis of paleomorphology, stratigraphy and seismic facies has revealed repeated large-scale slope failures that have governed the sedimentary architecture and morphology of the area throughout the Plio-Quaternary. The depositional architecture of the Gebra Valley, which is the most striking morphological feature in the area, determine the asymmetrical morphology of the complex that is characterized, from east to west, by an open-slope margin flanking the sidewall of the Gebra Valley, the Gebra Valley itself and a SW margin that is connected to the Magia area by a large scar approximately 7.8 km to the SW. The Gebra Valley is a Quaternary debris valley resulting from repeated large-scale mass-transport and cut-and-fill processes. In contrast, the Magia area is dominated by unchannelized sedimentary instability processes, resulting in a different sedimentary architecture and morphology. The nearsurface sediments in the Gebra-Magia Complex document the continuous occurrence of recent mass movements, as also evidenced by flows transported downslope as unchannelized or channelized flows. Taking into account the presence of faults and the stratigraphic correlation established with glacial periods, the genesis of the complex could have been controlled by the interplay of both the tectonic history of the Bransfield Basin and the glacial cycles that allowed grounding events to reach the upper continental slope Peer Reviewed