Plume push force: a relevant driver of plate tectonics that can be constrained by horizontal and vertical plate motions

Abstract

<p>Earth's surface moves in response to a combination of tectonic forces from the thermally convective mantle and plate boundary forces. Plate motion changes are increasingly well documented in the geologic record and they hold important constraints. However, the underlying forces that initiate such plate motion changes remain poorly understood. I have developed a novel 3-D spherical numerical scheme of mantle and lithosphere dynamics, aiming to exploit information of past plate motion changes in quantitative terms. In order to validate the models and single out those most representative of the recent tectonic evolution of Earth, model results are compared to global plate kinematic reconstructions. Additionally, over the past years a pressure driven, so-called Poiseuille flow, model for upper mantle flux in the asthenosphere has gained increasing geodynamic attention–for a number of fluid dynamic arguments. This elegantly simple model makes a powerful testable prediction: Plate motion changes should coincide with regional scale mantle convection induced elevation changes (i.e., dynamic topography). For this the histories of large scale vertical lithosphere motion recorded in the sedimentary record holds important information.</p><p>Here, I will present analytical results that help to better understand driving and resisting forces of plate tectonics – in particular the plume push force. Moreover, numerical results indicate that mantle convection plays an active role in driving plate motions through pressure driven upper mantle flow. Altogether, theoretical and observational constrains provide powerful insights for geodynamic forward and inverse models of past mantle convection.</p>