Effects of a viscoelastic lithosphere on the isostatic bedrock response
The lithosphere responds to loading by elastic flexure which is followed by viscous relaxation, the amount of which depends on the stress duration. This study compares results of an Earth model in which the lithosphere is modelled as a purely elastic layer and as a more general viscoelastic solid overlain by a rigid crust. It shows the emergence of a noticeable difference in the short wavelength (1×102–5×102 km) component of the bedrock deformation after loading durations of the order of 105–106 yr assuming a lower lithosphere viscosity of the order of 1023–1024 Pa.s. In particular, for the long-term loading hypothesised to be imposed by the East Antarctic ice sheet, we find that aviscoelasticlithosphere yields a more local deformation pattern to which ice sheet dynamics are highly sensitive. It confirms that modelling of the Antarctic long-term evolution would benefit from a fully coupled ice/bedrock approach in which the lithosphere would be represented by aviscoelastic solid.