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Speaker: Kaixuan Kang, Postdoctoral Fellow, University of Texas Institute for Geophysics

Host: Benjamin Keisling

Title: The Effects of Non-Newtonian Rheology on Relative Sea Level Change Induced by Glacial Isostatic Adjustment Process and its Implications on Antarctic Ice Sheet Evolution

Abstract: Studies of glacial isostatic adjustment (GIA) – the ongoing, viscoelastic response of the Earth to the ice and ocean loading associated with last ice age – remains an active area of geophysical research, in part because of its central importance in studies of modern polar ice sheet stability. With very few exceptions, GIA models have assumed a Newtonian rheology, that is, a linear relationship between stress and strain rate, with viscosity in the mantle acting as the proportionality constant. However, laboratory experiments on rock deformation, observational studies of seismic anisotropy, and modeling of mantle dynamic processes strongly suggest that non-Newtonian rheology may prevail in the upper mantle of Earth. In this presentation, I will discuss the effects of non-Newtonian mantle rheology on ice age geodynamics, with a focus on understanding the physical process and mechanism. Our results demonstrated that rapid deglaciation may induce large stress in the mantle, leading to a reduction in the regional upper mantle effective viscosity of more than one order of magnitude. The weakened effective viscosity leads to an initially fast relaxation stage followed by a slow relaxation stage, which should manifest in relative sea level observables as a quasi-L shape. I will also discuss how we can use these insights to improve our understanding of the ongoing signal of GIA in Antarctica and the Antarctic Ice Sheet Evolution for my ongoing and future proposed work.