La deglaciación de las áreas libres de hielo de las islas Shetland del Sur (Antártida). Ejemplos de Byers (Livingston) y Barton (King George)

Abstract

The process of deglaciation of the present-day ice-free environments in the Maritime Antarctica has profound geomorphological and ecological implications. However, the timing of glacier retreat is still poorly understood. This is the case of the deglaciated areas existing in Byers (Livingston Island) and Barton (King George Island) peninsulas. The dating of the basal sediments collected from different lakes in these two peninsulas allowed inferences of the ages of formation of each lake. The integration of these ages enables the reconstruction ofthe spatial and temporal pattern of deglaciation of these areas. The chronological framework has been establishedusing two complementary techniques: radiocarbon and thermoluminescence dating. In both peninsulas the deglaciation started during the Early Holocene, around 8 ka cal BP. The areas located far away from the current ice domes and the highest peaks in the two peninsulas (nunataks) were the first areas to become ice -free. During the mid-Holocene (5-6 ka cal BP) the central part of these peninsulas was progressively deglaciated. Finally, during the Late Holocene glacier fronts remained confined to the current position defined by the present frontal moraines, with minor advances and retreats.

Holocene deglaciation of the northern Fildes Peninsula, King George Island, Antarctica

“…The age of deglaciation of the northern sector of the Fildes Peninsula shows a very similar pattern to that observed at Byers Peninsula, the largest ice‐free area in the SSI and an area from where further evidence of past environmental evolution is available. Here, lake sediment records revealed that the central plateau was deglaciated between 8.3 and 5.1 ka cal BP and that the ice cap has been relatively stable over the last two millennia, with the formation of a polygenic moraine (Oliva, Antoniades, Giralt, Granados, Pla‐Rabes, Toro, Liu, et al, 2016; Oliva, Antoniades, Giralt, Granados, Pla‐Rabes, Toro, & Sanjurjo, 2016; Toro et al, 2013). This peninsula is one of the few areas of the SSI where CRE has been directly applied to Holocene glacial records; results indicated the occurrence of two Neoglacial advances of the southern flank of the Rotch Dome Glacier as revealed by the clustering 36 Cl ages of the external line of erratic boulders (4.6 ± 0.8 ka) and one internal moraine ridge (1.0 ± 0.3 ka) near the edges of the ice cap (Palacios et al, 2020).…”