A joint inversion of receiver function and Rayleigh wave phase velocity dispersion data to estimate crustal structure in West Antarctica

• Published in: Geophysical Journal International
• Main Authors: Dunham, C.K., O’Donnell, J.P., Stuart, G W, Brisbourne, A.M., Rost, S., Jordan, T.A., Nyblade, A.A., Wiens, D.A., Aster, R.C.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Oxford University Press 2020
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Weddell Sea; West Antarctica; Amundsen Sea; Weddell; Byrd; Thurston; Ellsworth Land; Thurston Island; Haag; Whitmore Mountains; Anet; Byrd Subglacial Basin; Bentley Subglacial Trench; Antarc*; Antarctica; Pine Island
• Online Access: http://nora.nerc.ac.uk/id/eprint/528388/; https://academic.oup.com/gji/advance-article-abstract/doi/10.1093/gji/ggaa398/5895977

We determine crustal shear-wave velocity structure and crustal thickness at recently deployed seismic stations across West Antarctica, using a joint inversion of receiver functions and fundamental mode Rayleigh wave phase velocity dispersion. The stations are from both the UK Antarctic Network (UKANET) and Polar Earth Observing Network/Antarctic Network (POLENET/ANET). The former include, for the first time, 4 stations along the spine of the Antarctic Peninsula, 3 in the Ellsworth Land and 5 stations in the vicinity of the Pine Island Rift. Within the West Antarctic Rift System (WARS) we model a crustal thickness range of 18-28 km, and show that the thinnest crust (∼18 km) is in the vicinity of the Byrd Subglacial Basin and Bentley Subglacial Trench. In these regions we also find the highest ratio of fast (Vs = 4.0-4.3 km/s) (likely mafic) lower crust to felsic/intermediate upper crust. The thickest mafic lower crust we model is in Ellsworth Land, a critical area for constraining the eastern limits of the WARS. Although we find thinner crust in this region (∼30 km) than in the neighbouring Antarctic Peninsula and Haag-Ellsworth Whitmore block (HEW), the Ellsworth Land crust has not undergone as much extension as the central WARS. This suggests that the WARS does not link with the Weddell Sea Rift System through Ellsworth Land, and instead has progressed during its formation towards the Bellingshausen and Amundsen Sea Embayments. We also find that the thin WARS crust extends towards the Pine Island Rift, suggesting that the boundary between the WARS and the Thurston Island block lies in this region, ∼200 km north of its previously accepted position. The thickest crust (38-40 km) we model in this study is in the Ellsworth Mountain section of the HEW block. We find thinner crust (30-33 km) in the Whitmore Mountains and Haag Nunatak sectors of the HEW, consistent with the composite nature of the block. In the Antarctic Peninsula we find a crustal thickness range of 30-38 km and a likely dominantly ...