GPS evidence for a coherent Antarctic plate and for postglacial rebound in

GPS measurements collected between 1999 and 2002 in Marie Byrd Land, West Antarctica indicate no significant present motion between East and West Antarctica greater than 1–2 mm/year. Low strain rates imply that the Ross Sea rift is either inactive or active at a very low rate. This result indicates that the two subcontinents are likely joined as a single coherent lithospheric plate. They could have been joined since the end of Adare Trough spreading in Oligocene time. The volcanic activity in the Ross Sea sector at present such as at Mount Erebus is most likely related to mantle upwelling and not associated with continental rifting. GPS measurements of vertical rates indicate postglacial rebound of up to 12F 4 mm/year in western Marie Byrd Land (wMBL). Errors are scaled 1r. The rock uplift rates are consistent with postglacial rebound models of significant ice thinning in the eastern Ross Ice Shelf in the late Holocene. D 2004 Elsevier B.V. All rights reserved.