The seismic structure of the Antarctic upper mantle

Abstract

AbstractThe deployment of seismic stations and the development of ambient noise tomography as well as new analysis methods provide an opportunity for higher-resolution imaging of Antarctica. Here we review recent seismic structure models and describe their implications for the dynamics and history of the Antarctic upper mantle. Results show that most of East Antarctica is underlain by continental lithosphere to depths of approximately 200 km. The thickest lithosphere is found in a band 500–1000 km inboard from the Transantarctic Mountains, representing the continuation of cratonic lithosphere with Australian affinity beneath the ice. Dronning Maud Land and the Lambert Graben show much thinner lithosphere, consistent with Phanerozoic lithospheric disruption. The Transantarctic Mountains mark a sharp boundary between cratonic lithosphere and the warmer upper mantle of West Antarctica. In the southern Transantarctic Mountains, cratonic lithosphere has been replaced by warm asthenosphere, giving rise to Cenozoic volcanism and an elevated mountainous region. The Marie Byrd Land volcanic dome is underlain by slow seismic velocities extending through the transition zone, consistent with a mantle plume. Slow-velocity anomalies beneath the coast from the Amundsen Sea Embayment to the Antarctic Peninsula are likely to result from upwelling of warm asthenosphere during subduction of the Antarctic–Phoenix spreading centre.