Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica

Kassab, Christine M., Licht, Kathy J., Petersson, Rickard, Lindbäck, Katrin, Graly, Joseph and Kaplan, Michael R. (2020) Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica. Jourrnal of Glaciology, 66 (255). pp. 49-60. ISSN 0022-1430

[img]
Preview
Text (Advance online version)
formation_and_evolution_of_an_extensive_blue_ice_moraine_in_central_transantarctic_mountains_antarctica.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (2MB) | Preview
Official URL: https://doi.org/10.1017/jog.2019.83

Abstract

Mount Achernar moraine is a terrestrial sediment archive that preserves a record of ice-sheet dynamics and climate over multiple glacial cycles. Similar records exist in other blue ice moraines elsewhere on the continent, but an understanding of how these moraines form is limited. We propose a model to explain the formation of extensive, coherent blue ice moraine sequences based on the integration of ground-penetrating radar (GPR) data with ice velocity and surface exposure ages. GPR transects (100 and 25 MHz) both perpendicular and parallel to moraine ridges at Mount Achernar reveal an internal structure defined by alternating relatively clean ice and steeply dipping debris bands extending to depth, and where visible, to the underlying bedrock surface. Sediment is carried to the surface from depth along these debris bands, and sublimates out of the ice, accumulating over time (>300 ka). The internal pattern of dipping reflectors, combined with increasing surface exposure ages, suggest sequential exposure of the sediment where ice and debris accretes laterally to form the moraine. Subsurface structure varies across the moraine and can be linked to changes in basal entrainment conditions. We speculate that higher concentrations of debris may have been entrained in the ice during colder glacial periods or entrained more proximal to the moraine sequence.

Item Type: Article
Uncontrolled Keywords: Blue ice; ground-penetrating radar; moraine formation
Subjects: F600 Geology
F700 Ocean Sciences
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Elena Carlaw
Date Deposited: 13 Jan 2020 10:51
Last Modified: 19 Mar 2020 09:45
URI: http://nrl.northumbria.ac.uk/id/eprint/41889

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics