Paleoglaciological study of Borgmassivet, Dronning Maud Land, East Antarctica, using WorldView imagery


Contact
Olaf.Eisen [ at ] awi.de

Abstract

Paleoglaciological reconstructions based on glacial geological and geomorphological traces are the basis for testing and constraining numerical models of ice sheet extent and dynamics. In MAGIC-DML (“Mapping, Measuring and Modelling Antarctic Geomorphology and Ice Change, in Dronning Maud Land”) we aim to reconstruct the timing and pattern of ice surface elevation changes since the mid-Pliocene across western Dronning Maud Land, East Antarctica. The choice of study area is motivated by an absence of empirical field data and considerable ice sheet model uncertainties. We present a remote sensing-based mapping of glacial geomorphology and structures on the ice sheet surface for a coastal-inland transect including Ahlmannryggen-Borgmassivet-Kirwanveggen using high-resolution WorldView imagery. The primary aim of the study is to map traces of a thicker ice sheet on nunatak slopes that were formerly partly or entirely covered during surface highstands. Panchromatic and multispectral images were analysed in a multi-step procedure using ArcGIS, including image processing and mosaicking, visual feature recognition, and mapping. The identification of crucial landforms (such as till veneers and erratic boulders) required the adoption of some assumptions to differentiate, for example, till from regolith. Where patterned ground was mapped, we infer a presence of till rather than regolith since subglacial erosion is more likely to produce fine material than subaerial weathering. Huge boulders on plateau surfaces are mapped as erratics because they could not have been delivered by slope processes to local highpoints. Sediment veneers with ridges were mapped as till because the ridges are inferred to originate from reworking by ice. However, because of the necessity to invoke assumptions and the absence of crosscutting relationships between landforms, we are unsure of the reliability of derived paleo-ice sheet reconstructions. At face value, the data indicates thicker ice in the past from the altitude above present ice surface of till cover and erratics on some nunataks. Mapping and landform interpretations will be verified during the MAGIC-DML 2017-18 field season. The mapping of structures on the ice sheet surface is used to (i) infer ice flow characteristics; This was possible by assessing the distribution of primarily blue ice areas, crevasse fields, and supraglacial moraines, and by analysing their connection to wind directions and ablation rates; and (ii) yield target field routes to potential cosmogenic nuclide (CN) sampling locations along vertical transects on nunataks. The timing derived from CN dating will permit the delineation of ice sheet surface elevations as targets for ice sheet modeling.



Item Type
Conference (Poster)
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
Past Antarctic Ice Sheet Dynamics (PAIS) Conference 2017, 10 Sep 2017 - 15 Sep 2017, Trieste, Italy.
Eprint ID
45504
Cite as
Elena, S. , Dymova, T. , Newall, J. C. , Blomdin, R. , Fredin, O. , Stroeven, A. P. , Bernales, J. , Eisen, O. , Fabel, D. , Neil F., G. , Harbor, J. M. , Hättestrand, C. , Lifton, N. A. , Prange, M. and Rogozhina, I. (2017): Paleoglaciological study of Borgmassivet, Dronning Maud Land, East Antarctica, using WorldView imagery , Past Antarctic Ice Sheet Dynamics (PAIS) Conference 2017, Trieste, Italy, 10 September 2017 - 15 September 2017 .


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