Thursday, 30 August 2007
4.PS-94
Crust and upper mantle in Dronning Maud Land/Antarctica retrieved from shear-wave splitting, receiver functions, refraction seismics and 3-D gravity modelling
Bettina Bayer1, Christian Müller2, David W. Eaton3, Wolfram H. Geissler1, Alfons Eckstaller1, and Wilfried Jokat1. (1) Alfred-Wegener-Institute for Polar-and Marine Research, Am alten Hafen 26, Bremerhaven, Germany, (2) FIELAX GmbH, Schifferstrasse 14, Germany, (3) Department of Earth Sciences, University of Western Ontario, London, ON ON, N6A 5B7, Canada
The crust and upper mantle of Dronning Maud Land (DML), Antarctica, have been investigated using teleseismic data from broadband seismograph stations deployed at temporary and permanent locations and recordings from a seismic refraction experiment. For shear-wave splitting analyses the observed anisotropy can in most cases be related to major tectonic events that formed the geological features of the present-day Antarctic continent. We rule out an anisotropic contribution from recent asthenospheric flow. An abrupt change in the fast axis direction of the shear-waves and a remarkable Moho jump beneath the Kottas mountains appears to mark a suture between the Grunehogna craton, a fragment of the Kalahari-Kaapvaal craton in southern Africa, and the Mesoproterozoic Namaqua-Natal belt. In general, the Moho increases from the coast towards the mountain ranges of Wohlthatmassif and Kottas, where thick crust between 45-53 km is found. The Vp/Vs-ratio are similar within geological units but different throughout DML.