GPR-Based Characterization of Retrogressive Thaw Slumps Near Eureka, Ellesmere Island, Canadian High Arctic

Details GPR-Based Characterization of Retrogressive Thaw Slumps Near Eureka, Ellesmere Island, Canadian High Arctic GPR-Based Characterization of Retrogressive Thaw Slumps Near Eureka, Ellesmere Island, Canadian High Arctic

Dec 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p23a1618g&link_type=abstract

American Geophysical Union, Fall Meeting 2010, abstract #P23A-1618

Physics

[0770] Cryosphere / Properties, [0794] Cryosphere / Instruments And Techniques, [5462] Planetary Sciences: Solid Surface Planets / Polar Regions, [6225] Planetary Sciences: Solar System Objects / Mars

Scientific paper

We report on investigations of retrogressive thaw slumps developed in permafrost near Eureka on Ellesmere Island, Nunavut. The study area consists of lowlands of the Slidre Fiord region, west-central Ellesmere Island. This region is located in the continuous permafrost zone, and forms part of a polar desert that extends across the High Arctic. The study area is predominantly underlain in the near surface by clastic and carbonate units of the Sverdrup Basin, and local terrain beneath the level of the Holocene marine limit (~150 m asl) is discontinuously mantled by ~1 to 15 m of marine silts and clays. Though bedrock units here generally do not contain significant amounts of excess ice, the Holocene marine sediments are widely associated with extensive bodies of massive ice. Regional degradation of massive ice and associated ice-rich sediments has resulted in the widespread development of thermokarst features including retrogressive thaw slumps. In July 2010, we collected ground penetrating radar (GPR) data at several slump sites using two commercially available systems at frequencies of 100 and 200 MHz. These data were used to investigate the dimensions and internal structure of local ice bodies, which are of interest in the study of regional climate dynamics, and which also represent possible analogs for high-latitude permafrost features on Mars. The study of two large slumps (several tens of meters across) was emphasized in this work: 1) an inactive and stabilized feature; and 2) a slump that is currently experiencing active headwall retreat. Both slumps occur in terrain characterized by an active layer of ~0.3 to 1 m thickness, and the presence of well-developed ice-wedge polygons. At the active slump, several meters of massive segregated ice are exposed along the headwall beneath ~0.6 to 3 meters of soil and frozen sediment. GPR sections show the base of the massive ice at depths of 5 to 15 m, as well as the presence of a number of horizontal and dipping reflectors within underlying sedimentary units of Jurassic and Cretaceous age. The GPR data offer insight into the stratigraphic relationships between local segregated ice and the underlying bedrock, and have the potential to help illuminate the mechanisms by which local massive ice bodies originally developed. In addition, the results of this study are relevant to the potential effectiveness of, and likely obstacles to, the use of GPR in the investigation of analogous features on Mars.

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