An airborne EM survey of the McMurdo Dry Valleys in Antarctica
Tuesday, 11 June 2019: 09:15
Davie West Building, DW103 (Florida Atlantic University)
Esben Auken1, Thue Sylvester Bording2, Peter T Doran3,4, Hilary A Dugan5, Nikolaj Foged1,6, Neil Foley7, Ricardo Garza Giron7, Denys Grombacher2, Jill Mikucki8, Lars Jensen1, Krista F Myers9, T.J. Rogers10, Slawek M Tulaczyk7 and Ross A Virginia11, (1)Aarhus University, Department of Geoscience, Aarhus C, Denmark, (2)Aarhus University, Department of Geoscience, Aarhus, Denmark, (3)Boulder, CO, United States, (4)Louisiana State University, Department of Geology & Geophysics, Baton Rouge, LA, United States, (5)University of Wisconsin, Department of Integrative Biology, Madison, WI, United States, (6)Gaborone, Botswana, (7)University of California Santa Cruz, Department of Earth and Planetary Sciences, Santa Cruz, CA, United States, (8)University of Tennessee, Department of Microbiology, Knoxville, TN, United States, (9)Louisiana State University, Department of Geology and Geophysics, Baton Rouge, LA, United States, (10)University of Tennessee, Department of Microbiology, Knoxville, United States, (11)Dartmouth College, Environmental Studies Program, Hanover, NH, United States
Abstract:
The McMurdo dry valleys are a series of mostly-snow free, very low humidity valleys near McMurdo Sound in Antarctica. Despite extreme conditions in the dry valleys, where mean annual temperatures are as low as -20 C, there exist thriving microbial communities in many of the region’s lakes, ponds, and soils. One such community, that houses iron-utilizing microbes, contributes to the development of a feature known as Blood Falls, a blood-red colored stain at the front of the Taylor Glacier, which occurs due to discharge of iron-rich brine. The first Antarctic airborne EM survey, conducted in 2011, discovered an unfrozen brine layer beneath Taylor Glacier that is believed to be the source of the discharged brine. These EM findings expanded the known range of this microbial community into an extensive habitat beneath the glacier. The expanse of this relatively thin brine reservoir at the base of the glacier was previously unknown, but is extremely important to understanding Taylor Glacier’s dynamics, as well as providing a laboratory for studying life in extreme conditions and can serve as an analogue for extraterrestrial targets.
In this study, a much larger scale airborne EM mapping campaign was undertaken. Surveys were flown in neighboring valleys targeting many of the major glaciers in the region, extending the survey into data poor (in terms of subsurface mapping) regions of the valley networks. Preliminary results from the survey will be discussed, including identification of previously unknown liquid brine reservoirs beneath a number of glaciers in the region and a mapping of the region surrounding Don Juan Pond, the second saltiest body of water on Earth. Further discussion about the prevalence of strong induced polarization effects in airborne EM data from the Wright Valley will also be given. Collectively these new observations suggest briney subsurface reservoirs along the coastal margins of Antarctica are more extensive than previously thought.
