Evolución geomorfológica y dinámica histórica del glaciar Schiaparelli (54°S), Cordillera de Darwin, Tierra del Fuego, Chile
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2020
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Universidad Andrés Bello
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El glaciar Schiaparelli es un glaciar de valle ubicado a los pies del Monte Sarmiento en Tierra del Fuego que desprende en un lago progracial, el lago Azul. Es uno de los glaciares más grandes ubicados en Cordillera de Darwin y en los últimos monitoreos realizados ha experimentado grandes variaciones frontales. Para estudiar los rasgos geomorfológicos del glaciar Schiaparelli y las variaciones que ha tenido en los últimos años, se analizaron imágenes satelitales, modelos digitales de elevación (DEM), imágenes de vehículo automático no tripulado (VANT) y un mapeo geomorfológico levantado en la campaña de terreno en marzo de 2020.
Las morfologías reconocidas en este estudio contemplan tanto formas erosivas (circos, artesas, valles colgados y rocas aborregadas) como depositacionales (morrenas, depósitos fluvioglaciares y dirt cones). De los procesos depositacionales se desprende que a medida que ha retrocedido el glaciar han ido formando morfologías de diversas características, lo que evidencia: i) velocidad del hielo alta; ii) disminución del contenido de escombros del glaciar o una mayor distribución de los depósitos, asociado a un retroceso más rápido del glaciar; y iii) ablación diferencial evidenciado en la distribución de los dirt cones. Las morfologías erosivas a macroescala evidencian la altura e intensidad de la erosión de los cuerpos de hielo, mientras que aquellas de mesoescala en las inmediaciones del frente glaciar indican orientación y dirección del flujo predominantemente hacia el W, junto con una significancia glaciológica que definen que el origen de estas morfologías fue por i) una base de hielo caliente; ii) una carga basal de escombros del hielo; iii) presiones del hielo sobre el lecho rocoso normales a bajas; iv) presencia de abundante agua de deshielo basal; v) velocidad de deslizamiento del hielo rápida; vi) formación bajo hielo delgado; y vii) cambios locales en las presiones del glaciar.
Las evidencias reunidas en este trabajo revelan que el paisaje actual fue modelado por los glaciares que existieron en la zona en el Último Máximo Glaciar (LGM), siendo el único glaciar del cuadrángulo de estudio que subsiste en la actualidad el glaciar Schiaparelli, el cual ha dejado evidencia de su retroceso histórico en sus geoformas erosivas y depositacionales. Además, el comportamiento del glaciar no solo está influenciado por la variabilidad climática reciente, sino también por ser un glaciar desprendente en lago.
The Schiaparelli glacier is a valley glacier located at the foothill of Mount Sarmiento, in the Isla Grande de Tierra del Fuego, that flows into a progracial lake called Lago Azul. It is one of the largest glaciers located in Cordillera de Darwin and in the latest monitoring carried out it has experienced large frontal variations. To study the geomorphological features of the Schiaparelli glacier and the variations it has experienced in recent years, satellite images, digital elevation models (DEM) and unmanned automatic vehicle images (UAV) were analyzed together with geomorphological mapping carried out in a campaign in March 2020. The morphologies recognized in this study include both erosive (cirques, glacial troughs, hanging valleys and Roche moutonnée) and depositional forms (moraines, fluvioglacial deposits and dirt cones). Depositional forms show that as the glacier has receded, morphologies of various characteristics have been formed, showing: i) high ice speed; ii) a decrease in the glacier debris content, or a greater distribution of the deposits associated with a faster retreat of the glacier; and iii) differential ablation evidenced in the distribution of dirt cones. The macro-scale erosive morphologies show the height and intensity of the erosion of the ice bodies, while those of the mesoscale in the vicinity of the glacier front indicate orientation and direction of the flow predominantly towards the west, together with a glaciological significance that defines that the origin of these morphologies was due to i) a hot ice base; ii) a basal load of ice debris; iii) normal to low ice pressures on bedrock; iv) presence of abundant basal meltwater; v) fast ice sliding speed; vi) formation under thin ice; and vii) local changes in glacier pressures. The evidence gathered in this work reveals that the current landscape was shaped by the glaciers that existed in the area in the Last Glacier Maximum (LGM), being the only glacier in the study area that still subsists the Schiaparelli glacier, which has left evidence of its historical retreat in its erosive and depositional geoforms. Furthermore, the behavior of the glacier is not only influenced by recent climatic variability, but also by being a detaching glacier in a lake.
The Schiaparelli glacier is a valley glacier located at the foothill of Mount Sarmiento, in the Isla Grande de Tierra del Fuego, that flows into a progracial lake called Lago Azul. It is one of the largest glaciers located in Cordillera de Darwin and in the latest monitoring carried out it has experienced large frontal variations. To study the geomorphological features of the Schiaparelli glacier and the variations it has experienced in recent years, satellite images, digital elevation models (DEM) and unmanned automatic vehicle images (UAV) were analyzed together with geomorphological mapping carried out in a campaign in March 2020. The morphologies recognized in this study include both erosive (cirques, glacial troughs, hanging valleys and Roche moutonnée) and depositional forms (moraines, fluvioglacial deposits and dirt cones). Depositional forms show that as the glacier has receded, morphologies of various characteristics have been formed, showing: i) high ice speed; ii) a decrease in the glacier debris content, or a greater distribution of the deposits associated with a faster retreat of the glacier; and iii) differential ablation evidenced in the distribution of dirt cones. The macro-scale erosive morphologies show the height and intensity of the erosion of the ice bodies, while those of the mesoscale in the vicinity of the glacier front indicate orientation and direction of the flow predominantly towards the west, together with a glaciological significance that defines that the origin of these morphologies was due to i) a hot ice base; ii) a basal load of ice debris; iii) normal to low ice pressures on bedrock; iv) presence of abundant basal meltwater; v) fast ice sliding speed; vi) formation under thin ice; and vii) local changes in glacier pressures. The evidence gathered in this work reveals that the current landscape was shaped by the glaciers that existed in the area in the Last Glacier Maximum (LGM), being the only glacier in the study area that still subsists the Schiaparelli glacier, which has left evidence of its historical retreat in its erosive and depositional geoforms. Furthermore, the behavior of the glacier is not only influenced by recent climatic variability, but also by being a detaching glacier in a lake.
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Tesis (Geología)
Palabras clave
Geomorfología Climática, Glaciares, Tierra del Fuego (Chile), Reservas Naturales, Cambio del Medio Ambiente Global, Monitoreo Satelital