Geoformas submarinas y procesos glaciomarinos asociados al retroceso glaciar en la Bahía Borgen, Isla Anvers, Antártica
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2018
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es
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Universidad Andrés Bello
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Los ambientes glaciomarinos corresponden al lugar físico de convergencia entre el sistema marino y el sistema glacial, tal interacción propicia una excepcional sensibilidad a las variaciones climáticas en sistemas de gran alcance temporal, como es el ambiente polar antártico. Actualmente los procesos glaciomarinos observados en esta región se han visto intensificados, viéndose reflejado este comportamiento en cambios tanto en la composición y textura de los sedimentos como también en la estratigrafía y geoformas submarinas. Sumado a lo anterior, y dada la gran diversidad de fuentes de sedimentos y procesos que redistribuyen el material en estos ambientes, es un marco ideal para entender el registro sedimentario en la región noroccidental de la península Antártica.
En este sector, co-existen tres gradientes climáticos que modulan los procesos glaciomarinos afectando a fiordos y bahías; estos son: un clima polar seco, subpolar y polar húmedo, los cuales, al estar en una zona de transición climática, se están viendo alterados y cuyas consecuencias son reflejadas en la intensificación de dichos procesos en pequeñas bahías. De esta manera, el presente trabajo pretende establecer la dinámica entre las formas submarinas y procesos glaciomarinos asociados al retiro glaciar en bahía Borgen y dilucidar si estas son congruentes con las tendencias observadas en la región. Para lograr lo anterior, esta investigación contempló el procesamiento de datos de batimetría multihaz y de perfiladores de subfondo del buque R/V “Nathaniel B. Palmer” en sus campañas NBP0107 y NBP0703 como también por la lancha “Hugo Moyano” durante la Expedición Científica Antártica (ECA) N˚53 del INACH. También se incluyó una correlación de estos resultados con 6 testigos de sedimentos y una muestra de draga de sedimentos, los que fueron complementados con análisis de turbidez mediante CTD-T y posterior comparación con imágenes satelitales. De la interpretación de los resultados se logra definir 4 etapas en la dinámica de la línea de anclaje del glaciar, las cuales difieren acorde a su emplazamiento en la bahía, así se postula que los procesos preponderantes en estas etapas son: depositación por flujos de escorrentía, marcados por facies sísmicas caóticas; resedimentación subacuática por flujos gravitacionales, con predominio de facies sísmicas monticulares y procesos de dispersión de partículas suspendidas con alto grado de turbidez que generan plumas de sedimentos y ice-rafting, que se asocian a facies con laminación paralela y subparalela. Los resultados anteriores revelan que esta bahía está sujeta a ligeros períodos de avance y acentuados períodos de retroceso diferencial del frente glaciar para ambos flancos de la bahía; comportamiento que regionalmente sugiere que la zona de estudio está experimentando una transición climática de características subpolares.
The glaciomarines environments corresponds to the physical place where the marine and glacial systems converge, such interaction fosters an exceptional sensitivity to climatic variations of long term systems, as the Antarctic polar environment. Currently the glaciomarines processes observed in this region have been intensified, being reflected in composition and texture of the sediments, stratigraphy and underwater landforms. In addition to the above, and given the great diversity of sediment sources and processes that redistribute the material in these environments, it is an ideal framework to understand the sedimentary record in the northwestern region of the Antarctic Peninsula. This sector is under the influence of there are three climatic gradients that modulate the glaciomarines processes which are affecting fjords and bays; these are: a dry- polar climate, a warm sub polar and a wet polar climate, which, being in a zone of climatic transition, are being altered and whose consequences are intensificated in small bays. In this way, the present work aims to establish the dynamics between the submarine landforms and glaciomarines processes associated with the glacier retreat in Borgen Bay and if these are consistent with the trends observed in the region. The complete datasets for this study include processing of multibeam bathymetry data and subbottom profiles acquired by the R/V "Nathaniel B. Palmer" in its campaigns NBP0107 and NBP0703 as well as the "Hugo Moyano" rubber boat during the Scientific Expedition Antarctica (ECA) N˚53 of the INACH. A correlation of these results was also included with 6 piston cores and a sediment dredge sample, which were complemented with turbidity analysis by CTD-T and subsequent comparison with satellite imagery. From the interpretation of the results it is possible to define 4 stages in the grounding line dynamics, which differ according to their location in the bay, therefore it is postulated that the preponderant processes in these stages are: deposition by runoff flows, marked by chaotic seismic facies; submarine resedimentation by gravitational flows with predominance of monticular seismic facies and dispersion processes of suspended particles with high turbidity levels which generate sediment plumes and ice-rafting, being associated with parallel and subparallel lamination´s facies. In general terms, the association of the previous results reveals that this bay is subject to slight periods of advance and intense periods of differential retreat of the glacier front for both flanks of the bay; behavior that regionally suggests that the study area is undergoing a sub polar climatic transition.
The glaciomarines environments corresponds to the physical place where the marine and glacial systems converge, such interaction fosters an exceptional sensitivity to climatic variations of long term systems, as the Antarctic polar environment. Currently the glaciomarines processes observed in this region have been intensified, being reflected in composition and texture of the sediments, stratigraphy and underwater landforms. In addition to the above, and given the great diversity of sediment sources and processes that redistribute the material in these environments, it is an ideal framework to understand the sedimentary record in the northwestern region of the Antarctic Peninsula. This sector is under the influence of there are three climatic gradients that modulate the glaciomarines processes which are affecting fjords and bays; these are: a dry- polar climate, a warm sub polar and a wet polar climate, which, being in a zone of climatic transition, are being altered and whose consequences are intensificated in small bays. In this way, the present work aims to establish the dynamics between the submarine landforms and glaciomarines processes associated with the glacier retreat in Borgen Bay and if these are consistent with the trends observed in the region. The complete datasets for this study include processing of multibeam bathymetry data and subbottom profiles acquired by the R/V "Nathaniel B. Palmer" in its campaigns NBP0107 and NBP0703 as well as the "Hugo Moyano" rubber boat during the Scientific Expedition Antarctica (ECA) N˚53 of the INACH. A correlation of these results was also included with 6 piston cores and a sediment dredge sample, which were complemented with turbidity analysis by CTD-T and subsequent comparison with satellite imagery. From the interpretation of the results it is possible to define 4 stages in the grounding line dynamics, which differ according to their location in the bay, therefore it is postulated that the preponderant processes in these stages are: deposition by runoff flows, marked by chaotic seismic facies; submarine resedimentation by gravitational flows with predominance of monticular seismic facies and dispersion processes of suspended particles with high turbidity levels which generate sediment plumes and ice-rafting, being associated with parallel and subparallel lamination´s facies. In general terms, the association of the previous results reveals that this bay is subject to slight periods of advance and intense periods of differential retreat of the glacier front for both flanks of the bay; behavior that regionally suggests that the study area is undergoing a sub polar climatic transition.
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Geoformas Glaciales, Sedimentos (Geología), Chile