Document DetailsWISSARD at Subglacial Lake Whillans, West Antarctica: scientific operations and initial observations
|Authors:||Tulaczyk S, Mikucki JA, Siegfried MR, Priscu JC, Barcheck CG, Beem LH, Behar A, Burnett J, Christner BC, Fisher AT, Fricker HA, Mankoff KD, Powell RD, Rack F, Sampson D, Scherer RP, Schwartz SY, the WISSARD Science Team|
|Keywords:||Antarctic glaciology, ice streams, sediments|
|Periodical/Journal:||Annals of Glaciology|
A clean hot-water drill was used to gain access to Subglacial Lake Whillans (SLW) in late January 2013 as part of the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. Over 3 days, we deployed an array of scientific tools through the SLW borehole: a downhole camera, a conductivity-temperature-depth (CTD) probe, a Niskin water sampler, an in situ filtration unit, three different sediment corers, a geothermal probe and a geophysical sensor string. Our observations confirm the existence of a subglacial water reservoir whose presence was previously inferred from satellite altimetry and surface geophysics. Subglacial water is about two orders of magnitude less saline than sea water (0.37-0.41 psu vs 35 psu) and two orders of magnitude more saline than pure drill meltwater (<0.002 psu). It reaches a minimum temperature of -0.558C, consistent with depression of the freezing point by 7.019MPa of water pressure. Subglacial water was turbid and remained turbid following filtration through 0.45 mm filters. The recovered sediment cores, which sampled down to 0.8 m below the lake bottom, contained a macroscopically structureless diamicton with shear strength between 2 and 6kPa. Our main operational recommendation for future subglacial access through water-filled boreholes is to supply enough heat to the top of the borehole to keep it from freezing.