Post-rift sedimentary evolution of the Central Bransfield Basin (Antarctic Peninsula)

Abstract

[EN] The Central Bransfield Basin is located at the northernmost tip of the Antarctic Peninsula (West Antarctica). This investigation, focused in the morphology, stratigraphy and near-surface sedimentation, and based on acoustic, seismic and sedimentological methods, reveals the main sedimentary systems and processes involved in the stratigraphic architecture and growth pattern of the basin. Likewise, it provides clues about the interplay of the global and local factors that have controlled the basin sedimentary evolution during the post-rift stage and allows the reconstruction of depositional models. The most striking physiographic characteristic of the Central Bransfield Basin is the presence of slope platforms composing the middle domain of the slope, in both the Antarctic Peninsula and South Shetland Islands margins. This favors the occurrence of glacial and glaciomarine processes on this domain, representing a difference with other high-latitude margins, where these processes are restricted to the continental shelf. The morphologic elements identified on the Central Bransfield Basin may be grouped into four major sedimentary systems (glacial-glaciomarine, slope-basin, seabed fluid outflow and contourite). The development of these systems has occurred during the last glacial cycle and has been controlled by the glacial cyclicity, tectonics, physiography and oceanography. The post-rift seismic stratigraphy of the Antarctic Peninsular margin consists on two seismic sequences, S1 and S2, of glacial and glaciomarine origin, overlying the syn-rift record. S2 was deposited during the post-rift to the Mid-Pleistocene and can be subdivided into four seismic units composed of prograding wedges. S1 was deposited after the Mid-Pleistocene and is composed of prograding/aggrading deposits. This sequence is composed of five seismic units whose distribution was mostly governed by variations in the thermal regimes of the Antarctic Peninsula Ice Sheet. Climate and physiography are interpreted as the major factors controlling the stratigraphic architecture and growth pattern of the margin. [...]

[ES] Los estudios de procesos glaciales y glaciomarinos y sus productos sedimentarios en márgenes continentales de altas latitudes comenzaron a desarrollarse hace apenas 35 años, favorecidos por la disponibilidad de técnicas y buques oceanográficos adaptados a estos medios. A pesar de que el estudio de la geología marina en la Antártida presenta serias dificultades debidas al entorno, dicho estudio es necesario para la comprensión de los cambios climáticos en el pasado y para la predicción de los cambios que afectarán en el futuro a los sistemas naturales del planeta, ya que los márgenes continentales de la Antártida registran el comportamiento de los mantos de hielo, que tiene una gran repercusión en la regulación del clima, atmósfera, circulación oceánica y cambios del nivel del mar a escala global. [...]