Seismic, gravity, radar and magnetic measurements across the East Antarctic ice sheet from the Transantarctic Mountains to the Wilkes sub-glacial basin

A geophysical traverse, designed to image the sedimentary layer under the 3 km thick East Antarctic ice sheet, was completed across part of East Antarctic ice cap west of McMurdo Sound. The programme was jointly carried out by the Insitute of Geological and Nuclear Sciences, Victoria University of Wellington, United States Geological Survey and Stanford University. The completed traverse was 312 km long, starting 10 km west of the McMurdo Dome ice core drill site, 25 km west of the exposed bedrock of the Transantarctic Mountains (at Lashley Mountain) and ending 323 km west of the drill site over the Wilkes sub-glacial basin. Multi channel digital seismic data were collected using a shot interval of 150m, with coincident gravity, radar and magnetic measurements. Relative locations and elevations for the the entire traverse were measured at 150 m intervals by NZ Department of Survey and Land Information, and tied to three absolute GPS locations measured by the USGS. Barometer measurements were taken at 450 m intervals along the traverse. With this data, it was hoped to 1) image the extent of the Paleozoic to early-Mesozoic foreland basins beneath the ice cap, 2) find out whether younger sediments fill the Wilkes Basin and how far they extend, 3) image the Kukri Peneplain which separates the Beacon Supergroup sedimentary strata from the underlying metasedimentary and crystalline basement and 4) image dolerite sill emplaced in the Beacon Supergroup rocks, examining their lateral extent and the sill thickness to indicate the direction of the magmatic sources. The data was used to 1) provide quantitative constraints for modelling the uplift of the Transantarctic Mountains and the subsidence of the Wilkes basin, 2) indicate whether the Ferrar dolerite sills and basalts originated from an active mantle plume or whether they were the by product of rifting and passive upwelling and 3) help resolve the debate about climatic conditions and the size of the ice sheet in the Cenozoic, in particular whether parts of East Antarctica were deglaciated for much of the Late Cenozoic.