S-velocity model and inferred Moho topography beneath the Antarctic Plate from Rayleigh waves

Since 2007/2008, seismographs were deployed in many new locations across much of Antarctica. Using the records from 122 broadband seismic stations, over 10,000 Rayleigh wave fundamental-mode dispersion curves have been retrieved from earthquake waveforms and from ambient noise. Using the processed data set, a 3-D S-velocity model for the Antarctic lithosphere was constructed using a single-step surface wave tomographic method, and a Moho depth map was estimated from the model. Using the derived crustal thicknesses, the average ratio of lithospheric mantle and crustal densities of Antarctica was calculated. The calculated density ratio indicates that the average crustal density for Antarctica is much higher than the average values for continental crust or the average density of lithospheric mantle is so low as to be equal to low-density bound of Archean lithosphere. The latter implies that the lithospheric mantle in much of Antarctica should be old and of Archean age. The East Antarctic Mountain Ranges (EAMOR) represent a thick crustal belt, with the thickest crust (∼60 km) located close to Dome A. Very high velocities can be found at depths greater than 200 km beneath parts of East Antarctica, demonstrating that the continental lithosphere extends deeper than 200 km. The very thick crust beneath the EAMOR may represent the collision suture of East Gondwana with Indo-Antarctica and West Gondwana during the Pan-African orogeny.