Variations in crustal structure across the transition from West to East Antarctica, Southern Victoria Land

Abstract

SUMMARY The crustal structure beneath Ross Island and the Transantarctic Mountains (TAM) in Southern Victoria Land, Antarctica, is inferred using non‐linear inversion of receiver functions, derived from teleseismic earthquake data. Intermediate‐period waveforms from more than 160 teleseismic earthquakes recorded between January 1994 and January 2000 were used in the analysis. The inversion results confirm a crustal thickness of 19–21 km beneath Ross Island, consistent with previous multichannel seismic work. In addition we observe a crustal thickness of 18–20 km beneath the Ross Sea coastline immediately adjacent to the TAM. Further inland, beneath the TAM, the estimated Moho depths range from 30–33 km (∼30 km from the coast) to 36–40 km (∼85 km from the coast), deepening away from the coast beneath the TAM. These results are in broad agreement with previous seismic and gravity interpretations. Beneath the TAM a sharp mid‐crustal discontinuity is present at 8–14 km depth beneath the eastern‐most stations, but absent on the western side of the TAM, indicating a spatial change in the mid‐crustal composition.

Eocene to Miocene geometry of the West Antarctic Rift System

“…Regional crustal thickness variations have also been obtained by deep seismic-refraction profiles (Kogan 1972;Ito & Ikami 1986;Trey et al 1999;Leitchenkov & Kudryavtzev 2000;Bannister et al 2003). Segawa et al (1986) analysed the gradients of the power spectrum of Bouguer gravity anomalies that were determined from mean free-air anomaly estimates, whereas Groushinsky & Sazhina (1982) used a linear relation between Moho depths and mean Bouguer gravity anomalies.…”

Crustal and uppermost mantle structure variation beneath La Réunion hotspot track

“…Sambridge (1999b) showed using marginal probability density functions that the v P /v S ratio from the NA inversion is better resolved in the first layer and poorly resolved in the remaining layers. The inclusion of the v P /v S ratio serves primarily to allow for some of the effects of the sedimentary layer beneath the stations with no a priori information (Bannister et al 2003).…”

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

“…We used similar bounds for the 24 parameters to those of Shibutani et al (1996), Clitheroe et al The inversion is carried out in terms of 24 parameters, the V S values at the top and bottom of the gradient zone, the thickness of the gradient zone and the V P /V S ratio in each zone. The inclusion of the V P /V S ratio serves primarily to allow for some of the effects of the sedimentary layer beneath the stations with no a priori information (Bannister et al 2003). The NA method combines a Monte Carlo search technique and the properties of the Voronoi geometry in parameter space to find an ensemble of the best-fitting models and performs a global optimisation.…”