Paleoflexure

Abstract

We tested the assumption that flexural parameters measured in the present represent the lithosphere's mechanical response at its time of loading. We employed finite element models of cooling and non-cooling versions of one- and two-dimensional temperature distributions in a topographically loaded elastoviscoplastic oceanic lithosphere. Effective elastic thickness (T(e)) values of the cooling and non-cooling versions of a 1-D halfspace temperature field showed a 3% and 7% decrease, respectively, over about 40 Myr and supported the notion that the lithosphere's mechanical state at the time when loading ceased was effectively 'frozen in' as it cooled. The second set of models used a high-temperature perturbation beneath the load to simulate a magma conduit, with cooling and non-cooling conduit models exhibiting decreases in T(e) of 10% and 12%, respectively. As post-loading creep was responsible for the decreases in T(e), weaker rheology or higher temperature gradients would exacerbate the effects found here.