Variations of the effective elastic thickness over the Ross Sea and Transantarctic Mountains and implications for their structure and tectonics

The effective elastic thickness (T-e) is a proxy for lithospheric strength, and it depends primarily on the thermal gradient and composition of the lithosphere. Accordingly, spatial variations in T-e reflect changes in lithospheric properties and can be used to better understand the structure and tectonics of particular regions. In this paper, we investigate the Ross Sea and Transantarctic Mountains in terms of T-e using gravity and topographic data and the fan wavelet transform technique. The results reveal that relatively high T-e values dominate in the extensional basins of the Ross Sea and the hinterland of Transantarctic Mountains, whereas very low T-e values occur along the Transantarctic Mountain Front and in the deep ocean basin, with the lowest T-e values are found the vicinity of Ross Island and onshore in northern Victoria Land. In addition, the spatial variations in T(e )correlate well with lithospheric structure at the regional scale. By combining these findings with published seismic and heat flow data, we conclude that the presence of a zone of anomalously low T-e values parallel to the coast indicates that the lithosphere beneath the Transantarctic Mountain Front is extremely weak due to Cenozoic volcanism and extension. The T-e values increase from the Transantarctic Mountain Front (7 km) toward the center of the continent (similar to 80 km), which indicates that the continental lithosphere underlying East Antarctica belongs to the classic Gondwanan craton. The increase in T-e indicates that the Transantarctic Mountain Front marks the continent-continent boundary between East Antarctica and West Antarctica. The T-e values in the other extensional basins of the Ross Sea exhibit little variation and average approximately 35 km. The relatively high T-e values are interpreted to indicate that the lithosphere cooled and became mechanically stronger between late Cretaceous extension and Eocene-Neogene deposition. (C) 2017 Elsevier B.V. All rights reserved.