Crustal and upper mantle structure beneath Antarctica and surrounding oceans

Abstract

Abstract. We present and discuss a new model of the crust and upper mantle at high southern latitudes that is produced from a large, new data set of fundamental mode surface wave dispersion measurements. The inversion for a 2 ø x 2 ø shear velocity model breaks into two principal steps: first, surface wave tomography in which dispersion maps are produced for a discrete set of periods for each wave type (

Progress in modelling and observing Antarctic glacial isostatic adjustment

“…Seismic studies suggest a significant difference in Earth structure between East Antarctica and West Antarctica, with expectation of a thicker lithosphere in East Antarctica (Ritzwoller et al 2001). Compared to the rest of West Antarctica, the Antarctic Peninsula has a much thinner lithosphere and lower mantle viscosity associated with ancient plate subduction in this region (Simms et al 2012, Ivins et al 2011, Yegorova et al 2011.…”

Glimpses of East Antarctica: Aeromagnetic and satellite magnetic view from the central Transantarctic Mountains of East Antarctica

“…[32] The buried sources of the high-amplitude NW trending anomalies are most likely to be Precambrian basement older than Neoproterozoic age, based on the presence of Archean-Paleoproterozoic igneous and metamorphic rocks in the Nimrod Group, the thick high-velocity lithosphere imaged by seismic tomography in the region Morelli and Danesi, 2004;Ritzwoller et al, 2001], and the high amplitude of positive anomalies observed both in satellite data over the polar plateau and in the western end of our survey . In addition, the similarly oriented but finer-scale magnetic structure of the Nimrod basement complex (magnetic unit 1), whose magnetization was produced during Ross age metamorphism, probably reflects tectonic modification of preexisting Precambrian basement structure.…”

“…Because of the lack of continuation to a common elevation above the bed and the different flight line spacings, the amplitudes and wavelengths of anomalies from similar sources can vary from survey to survey. Despite such limitations, all of these data, combined with bed elevation [Ferraccioli et al, 2009;Lythe et al, 2000;Studinger et al, 2004Studinger et al, , 2006 and regional seismic tomography data [Morelli and Danesi, 2004;Ritzwoller et al, 2001], help to resolve critical features of the craton and outboard sequences. In particular, the western limit of the Neoproterozoic rift, and the extent of the Ross Orogen and Jurassic Ferrar dolerites can be mapped in more detail (Figure 9) than previously possible .…”

“…Despite recent advances in our understanding of the ages, kinematics and continuity of various orogenic belts within and adjacent to East Antarctica, extensive ice cover and remote access make it difficult to extrapolate isolated outcrop data from coastal areas and mountain ranges very far across the continent. Although surface wave velocity data image thick (>150 km), highvelocity (>∼5% shear wave velocity perturbation) aseismic lithosphere typical of Precambrian shields beneath much of East Antarctica Ritzwoller et al, 2001;Morelli and Danesi, 2004], they do not resolve orogenscale features. Hence, our understanding of the major crustal elements and the orogenic structures that juxtaposed them during assembly of the Rodinia and Gondwana supercontinents remains largely conjectural.…”

Scouting Craton’s Edge in Paleo-Pacific Gondwana

“…The eastern edge of highvelocity perturbations interpreted to relate to the Precambrian shield of East Antarctica (Ritzwoller et al, 2001) is approximately coincident with the eastern edge of the satellite magnetic high (Fig. 2).…”