Seismological imaging of the Antarctic continental lithosphere: a review Andrea Morelli * , Stefania Danesi Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, Rome 00143, Italy Received 16 June 2003; received in revised form 9 December 2003; accepted 9 December 2003 Abstract Tomographic analysis of seismic surface waves can map upper mantle structure under the Antarctic plate with reliability and fairly good detail, making the best use of the relatively limited dataset currently available. The large-scale features of Antarctic upper mantle agree with global views of Earth structure under oceans and continents. Low seismic velocities map the hot thermal anomaly under mid-ocean ridges down to approximately 150 km, stronger and wider under faster-spreading ridges. Cold continental roots show as seismically fast material under the older part of the continent (East), while the West Antarctic Rift System has a clearly slow wave signature. The seismically imaged lithosphere has variable thickness under the craton. It appears rather regular and about 220 km thick under Dronning Maud Land, but it deepens in the region stretching below Enderby Land, Gamburtsev Mountains, to Wilkes Land, where it reaches its maximum thickness, in excess of 250 km. This variability in lithospheric thickness is analogous to what has been found under other continents. The high velocity anomaly imaging cratonic roots appears to spread out, as a cool halo, off the passive continental margins, but terminates sharply towards the West Antarctic Rift System. The fast/slow contact runs under the Transantarctic Mountains and it is particularly sharp in the Ross Embayment, where seismically slow material, imaged down to 250 km, can be interpreted as the deep-seated hot anomaly related to a mantle plume. D 2004 Elsevier B.V. All rights reserved. Keywords: Seismic tomography; Lithosphere; Tectosphere; Surface waves; Precambrian cratons; Continental roots 1. Introduction The determination of properties of the continental lithosphere has represented a challenge to geophysi- cists and geologists for a few decades. The thick lithospheric ‘coating’ of Archean cratons—the oldest crust—is particularly intriguing, as it records a long tectonic history, and it carries the signature of past processes active in a tectonic regime different from the current one. Many continents have been exten- sively probed with seismic and seismological, gravi- metric, electrical, and magnetic methods; geochemical and heat flow data have been collected and interpreted (Artemieva et al., 2002). The resulting image is growing in complexity, and still leaves many open issues. Relatively little is known about the lithospheric structure of Antarctica. Besides its obvious interest as the geologically least known continent—which, by the way, plays literally a central role in Gondwana 0921-8181/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.gloplacha.2003.12.005 * Corresponding author. Tel.: +39-6-51860443; fax: +39-6- 51860507. E-mail address: morelli@ingv.it (A. Morelli). www.elsevier.com/locate/gloplacha Global and Planetary Change 42 (2004) 155 – 165