RAID: RAPID ACCESS ICE DRILLING

Rapid access to deep ice in the ice caps of Antarctica and Greenland will provide the first opportunity to systematically study spatial variability in deep ice, subice geology, and the interface between them. This unique ability will allow us to study, for example, the Milankovitch transition from 40 kyr to 100 kyr climate cycles (by sampling ice as old as ~1.5 Ma ice), and to document the presence of Eemian-age ice to test models of ice sheet collapse in West Antarctica (~125 Ka). Rapid access through deep ice will also allow us to explore the deep interior geology of Antarctica for the first time. As the last continental frontier, the Antarctic lithosphere is virtually unknown except by extrapolation from coastal outcrop and limited geophysical data. Recent attempts to reveal the geological substrate beneath the major ice caps by means of ice- sheet margin glacial deposits and geophysical potential-field data provide a limited framework for understanding the geology of the Antarctic interior. Direct sampling by rock coring, however, will enable us to evaluate the bed conditions at the base of the ice sheets, characterize geological features imaged with geophysical data, and test models of cratonic growth related to supercontinent assembly in the Mesoproterozoic (~1 Ga). In both cases, a single deep ice core and/or rock core would represent merely a single point in a continent-scale geosystem. Such a new technology will define geothermal flux and basal properties, allow study of ice dynamics, and provide constraints for ice-sheet modeling. We advocate development of drilling technology that will enable the ability to quickly access deep ice and the rock below in a large number of sites in order to capture as complete a spatial and temporal record of the coupled ice-rock system as possible.