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Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)
The West Antarctic Rift System provides the underlying geological template over which the West Antarctic Ice Sheet, the largest remaining marine ice sheet on Earth, flows. In this paper we used new airborne gravity data over the Pine Island Glacier region to reveal crustal thickness variations, shedding new light on the structure of the West Antarctic Rift System. Of major significance is the identification of the Pine Island Rift, which features the thinnest crust (~19km thick) imaged so far beneath the West Antarctic Ice Sheet.
The areas of maximum thinning occur in linear zones corresponding with the Byrd Subglacial Basin and the newly identified Pine Island Rift. Between regions of extreme crustal thinning ~26km thick crust is found. We suggest that the pattern of crustal thickness relates to the evolution of the West Antarctic Rift System, with initial regionally distributed rifting in the Cretaceous, followed by Cenozoic narrow-mode rifting. Narrow-mode rifting within the Pine Island Rift is particularly important as it may serve as a geological template for enhanced glacial flow associated with Pine Island Glacier. The glacier forms part of the Amundsen Sea Embayment region, a key sector of the ice sheet, which is contributing to accelerated global sea-level rise.
T.A. Jordan, F. Ferraccioli, D.G. Vaughan, J.W. Holt, H. Corr, D.D. Blankenship and T.M. Diehl
Geological Society of America Bulletin 2010;122;714-726, doi: 10.1130/B26417.1