Antarctic palaeotopography

Abstract

The development of a robust understanding of the response of the Antarctic Ice Sheet to present and projected future climatic change is a matter of key global societal importance. Numerical ice sheet models that simulate future ice sheet behaviour are typically evaluated with recourse to how well they reproduce past ice sheet behaviour, which is constrained by the geological record. However, subglacial topography, a key boundary condition in ice sheet models, has evolved significantly throughout Antarctica's glacial history. Since mantle processes play a fundamental role in the generation and modification of topography over geological timescales, an understanding of the interactions between the Antarctic mantle and palaeotopography is crucial for developing more accurate simulations of past ice sheet dynamics. This chapter provides a review of the influence of the Antarctic mantle on the long-term evolution of the subglacial landscape, through processes including structural inheritance, flexural isostatic adjustment, lithospheric cooling and thermal subsidence, volcanism and dynamic topography. The uncertainties associated with reconstructing these processes through time are discussed, as are important directions for future research and the implications of the evolving subglacial topography for the response of the Antarctic Ice Sheet to climatic and oceanographic change.

A cross-cultural exploration of compassion, and facilitators and inhibitors of compassion in UK and Sri Lankan people

“…It is noteworthy that there was no gender difference in the UK group, which raises the question whether the autonomous social background may have prevented UK females from seeking compassion, leading them to believe that others are not compassionate towards them. In fact, distance is identified as a positive cultural value in the UK, which links with respect for individual autonomy (Paxman, 2007). The impact of autonomy on seeking compassion, therefore, needs further exploration.…”

An introduction to the geochemistry and geophysics of the Antarctic mantle

“…In this Memoir, several open questions are tackled, such as how does the mantle support mountain ranges (Paxman 2021) and are there multiple Antarctic mantle plumes (Bredow et al (2021); Martin et al 2021a, b)? Definitively answering questions like these will require a combination of several models (lithosphere model, convection and composition).…”

“…Geodynamic models have been developed for simulating surface elevation at timescales from hours to millions of years due to, for example, tectonics, GIA, sediment erosion or loading, thermal subsidence and mantle-dynamics topography (Bredow et al 2021;Paxman 2021). An example of subsidence and uplift due to GIA can be seen in Figure 9.…”

“…Uncertainties in surface heat-flow estimates are reviewed. Paxman (2021) explains the importance of palaeotopography as a boundary condition for ice-sheet modelling. Paxman reviews how structural inheritance played a role in shaping early Antarctic ice sheets, and the role of the lithosphere and the mantle in shaping the topography.…”

Postseismic Deformation in the Northern Antarctic Peninsula Following the 2003 and 2013 Scotia Sea Earthquakes

“…The continent of Antarctica is made up of two geologically distinct regions with a thick cratonic lithosphere and high viscosity mantle in the East, and a lower viscosity active rift system in the West (Morelli & Danesi, 2004; Wiens et al., 2023). Analysis of gravity data has shown the effective elastic thickness of the lithosphere to be thinner in West than in East Antarctica (Pappa & Ebbing, 2023; Paxman, 2023). Recent seismic tomographic models (Lloyd et al., 2020; O'Donnell et al., 2019) have also highlighted strong lateral variations in the upper mantle structure across Antarctica with notable slower than average shear waves speeds for the Antarctic Peninsula, indicating lower viscosity there relative to the rest of Antarctica.…”