Abstract
AbstractRapid Access Ice Drill is a new drilling technology capable of quickly accessing the glacial bed of Antarctic ice sheets, retrieving ice core and rock core samples, and providing boreholes for downhole logging of physical properties. Scientific goals include searching for old ice near the glacial bed and sampling subglacial bedrock. During field trials near McMurdo Station on a piedmont glacier at Minna Bluff in the 2019–20 austral summer, we successfully completed a ‘top-to-bottom’ operational sequence in three boreholes by (1) augering through firn, (2) creating a borehole packer seal in non-porous ice, (3) establishing fluid circulation, (4) quickly drilling a borehole in ice at penetration rates up to 1.2 m min−1, (5) acquiring a short ice core at depth, (6) penetrating the glacial bed at a depth of ~677 m, (7) recovering a 3.2 m core of ice, basal till and subglacial bedrock, (8) optically logging the borehole on wireline, (9) testing hydrofracture potential by overpressuring the borehole fluid and (10) operating in an environmentally benign yet rapid field mode. Minna Bluff testing, therefore, demonstrates the effectiveness of this integrated system to drill rapidly through thick ice and penetrate across the glacial bed to take cores of bedrock.
Highlights
Exploration of the interior of the Antarctic ice sheet and its bed has proceeded slowly but steadily over several decades
Growing concern relates to stability of the East Antarctic ice sheet and its potential contribution to sea-level rise, which are highly uncertain and often overlooked (Fogwill and others, 2016)
Most of the Antarctic geological map remains blank due to ice cover, hampering understanding of how the Antarctic continent was assembled (Boger, 2011). This is best addressed by a survey program of short rock cores taken quickly from multiple sites beneath the ice in order to ground-truth interpretations made from geophysical remote-sensing data
Summary
Exploration of the interior of the Antarctic ice sheet and its bed has proceeded slowly but steadily over several decades.
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