Paleoflexure

Abstract

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 (Te) values of the cooling and noncooling 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 Te of 10% and 12%, respectively. As post-loading creep was responsible for the decreases in T,, weaker rheology or higher temperature gradients would exacerbate the effects found here.

Effects of lithospheric properties on the formation of Type 2 coronae on Venus

“…Although the coronae on Venus may have started forming hundreds of million years ago rather than tens of million years ago [e.g., Musser and Squyres , 1997; Koch and Manga , 1996; Smrekar and Stofan , 1997], the lithosphere is believed to be much stronger due to the lack of water. The results of Albert and Phillips [2000] suggest that the elastic thickness estimates for those coronae that are no longer active are likely to reflect original lithospheric thickness rather than a significantly larger value due to subsequent cooling of the lithosphere. However, both modeling studies and the examination of the geologic history of coronae indicates numerous phases of deformation can occur [ Copp et al , 1998; Guest and Stofan , 1999].…”

Thermal and crustal evolution of Mars

“…Derived elastic plate thicknesses and heat fluxes are assumed to be representative of the time of loading. Results from an elastoviscoplastic model of lithospheric deformation suggest that for a uniformly cooling plate this “frozen in” paleoflexure is reasonable, although estimates of effective elastic plate thickness from present‐day observations may be underestimated by 10% or more in areas affected by anomalously high temperatures (e.g., volcanic magma conduits) [ Albert and Phillips , 2000]. Zuber et al [2000] noted a discrepancy between their estimates of heat flux derived in this manner and earlier thermal evolution models [i.e., Schubert and Spohn , 1990], especially for ancient, southern, Noachian terrains.…”

Density and lithospheric structure at Tyrrhena Patera, Mars, from gravity and topography data

“…As a result, the elastic thickness T e will also decrease as a function of time, and the time corresponding to the observed paleo-flexure is determined by a competition between loading rate, lithospheric cooling rate, and stress relaxation (Albert and Phillips, 2000). However, it has been shown that the applied elasto-plastic rheology yields satisfactory results when compared to more realistic elasto-visco-plastic formulations for the single layer rheology considered here, but could overestimate the elastic thickness by up to 30% (Brown and Phillips, 2000) for multi-layer configurations.…”