The Last Glacial Maximum (LGM) Patagonian Ice Sheet (PIS) provides the unique potential to reconstruct the former meridional position and precipitation rates of the Southern Westerly Wind Belt (SWWB) due to its considerable latitudinal distance perpendicular to this global wind system. To use this potential, a high-resolution 3D reconstruction of the LGM PIS would be crucial, but knowledge about even the exact planform of this biggest Quaternary ice sheet on the Southern Hemisphere, excluding Antarctica, is still very poor. The widely accepted limits of the ‘Finiglacial’ ice sheet extent, mapped over 80 years ago by Caldenius (1932), has been identified as the LGM extent at many locations (e.g. Kaplan et al., 2004, 2008a,b; Singer et al., 2004; Hein et al., 2009). However, apart from the broadly correct assignation of the ‘Finiglacial’ limit to the LGM, its resolution remains poor, imperfect, and outdated, despite some later adaptations (e.g. Hollin and Schilling, 1981a; Clapperton, 1993) with small improvements. All attempts to provide 3D reconstructions (Hollin and Schilling, 1981a; Hulton et al., 1994, 2002) date back almost 15 years and did not match the poorly constrained glacial geomorphological record. This study presents a novel attempt to cast all relevant absolute dating locations of glacial landforms into a refined spatio-chronological context of the LGM extent of the PIS. Based on this newly set spatio-chronological context, a geographical information system (GIS)-based high-resolution LGM extent reconstruction, both in planform and in 3D, is presented within this study. In contrast to its predecessors, the applied GIS-based modelling approach enables a grade of reconstruction resolution for an ice sheet, that is as big as Spain and that is otherwise found only in local valley-scale glacier reconstructions. The spatial resolution of the GIS-based 3D ice-sheet reconstruction surface lies at 100 metres, as does the implemented topographic data. This leads to a spatial ice-sheet surface resolution that is at least 200 times higher than any previous attempt to cover the entire LGM PIS. The 3D reconstruction of the LGM PIS using the newly defined extent is in good agreement with observations on vertical ice extents (Boex et al., 2013) and displays, for the first time, a realistic interaction with the complex Patagonian topography. The area of the LGM PIS is, with ca. 504,500 km2 (±8.5%) roughly a fourth of the area of Greenland and represents 554,500 km3 (±10%) of ice or 1.38 metres (±10%) of sea-level equivalent. The now available 3D reconstruction provides a starting point that, after minor revisions, could potentially allow gauging accumulation rates along up to 2,300 km perpendicular to the SWWB and, thus, inferring valuable palaeo-climatic insights from the LGM.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:694698 |
| Date | January 2016 |
| Creators | Wolff, Ingo Wilhelm |
| Contributors | Glasser, Neil ; Hubbard, Alun |
| Publisher | Aberystwyth University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/2160/950c2c84-ce59-49f9-9946-19be41e9c750 |
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