THEORETICAL WORLD-WIDE SEA LEVEL CHANGE ASSOCIATED WITH NON-NEWTONIAN FLOW IN THE UPPER MANTLE

Abstract

The world-wide sea level change in the Holocene was calculated with non-Newtonian flow of ε ∝ σ3 in the upper mantle, where ε and σ represent strain rate and deviatoric stress. The relative sea level patterns based on this model are divided into three categories, i.e., glaciated region, forebulge region, and continental margin and oceanic island away from the glaciated region. But the relative sea levels at the oceanic islands may depend on their size. This size dependence may give an important constraint on the lower mantle viscosity. This model predicts that the hydro-isostatic adjustment in the Holocene away from the glaciated region is localized to the boundary between ocean and continent or island. The relaxation time to complete the world-wide isostatic adjustment may be several ten thousand years, so no world-wide adjustment of ocean basins owing to the load of meltwater has proceeded until the present.