Examining the Mantle Transition Zone Beneath the Transantarctic Mountains From Receiver Functions Using TAMSEIS Data

Larson, A M(alarson@geosc.psu.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States
Nyblade, A (andy@geosc.psu.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States
Weins, D (doug@mantle.wustl.edu) , Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130 United States
Anandakrishnan, S (sak@essc.psu.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States
Watson, T (tdw130@psu.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States
Benoit, M (mbenoit@erl.mit.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States
Shore, P (patrick@seismo.wustl.edu) , Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130 United States
Voight, D (voigt@geosc.psu.edu) , Department of Geosciences, Pennsylvania State University, University Park, PA 16802 United States

There is a significant geologic contrast between the East Antarctica Craton (EAC) and the accreted terranes that make up West Antarctica. The boundary between these two provinces is marked by the Transantarctic Mountains (TAM) that parallel the West Antarctica Rift System. The TAM are the largest non-compressional mountain chain in the world, but their origin is not fully understood. Also not well explained is the anomalously high topography of the EAC. A potential cause for both is a thermal upwelling, either a very broad (>500 km wide) anomaly or a narrower one (~100-200 km wide). To investigate these two unique tectonic features of the Antarctic continent, receiver-function stacking is being conducted with broadband seismic data collected by the 2000-2003 Transantarctic Mountain Seismic Experiment (TAMSEIS) to image topography on the 410 and 660 km discontinuities and the thickness of the transition zone. A deep-seated mantle thermal anomaly would evidence itself by creating topography on the 410 and/or 660 km discontinuities. After generating the receiver functions using a frequency-domain deconvolution with water-level stabilization, a geographical binning technique has been applied to better resolve lateral variations in structure. Preliminary results from stacking with a 1D velocity model suggest that the transition zone may be thicker than average, at least beneath parts of the TAMSEIS network under the TAM mountain front. Stacking with a 3D velocity model to correct for heterogeneity in the upper mantle and for variations in the thickness of the ice sheet should improve the quality of the stacks and allow us to image the discontinuities more clearly beneath the study area.