Crustal structure of the Transantarctic Mountains near the Ross Sea from ambient seismic noise tomography

Abstract

We derive a model for crustal shear wave velocities in the Transantarctic Mountains and surrounding areas of East Antarctica and the Ross Sea region of West Antarctica using Rayleigh wave Green's functions estimated from the cross correlation of ambient seismic noise recorded by the Transantarctic Mountains Seismic Experiment. Group velocity maps are determined from travel times measured from the Rayleigh waves filtered at periods between 5 and 23 s. The velocity maps are inverted for shear velocities across the region using a niching genetic algorithm. We observe only minor variation in crustal velocities beneath East Antarctica and the Transantarctic Mountains, and velocities are similar to those observed for Precambrian crust worldwide. Low velocities, which may be related to the presence of sediment, are observed at shallow depths beneath the Wilkes Subglacial Basin and the Aurora Subglacial Basin, but dispersion curves show that sediment thickness must be limited to less than about 2 km. In the Ross Sea, we observe low velocities at shallow depths from thick sediments and high velocities approaching mantle values between 16 and 20 km depth.