Topographic asymmetry of the South Atlantic from global models of mantle flow and lithospheric stretching

The methodology for building deforming regions into global plate reconstructions builds on the continuously closing plates framework described by Gurnis et al. (2012). Plates are defined within the open-source software GPlates (Boyden et al., 2011) by building polygons from a series of lines defining plate boundaries. The lines can move independently, so that the geometry of plate polygons continually change as a function of reconstruction time. Within this original framework, plate velocities within each plate polygons were based on the stage rotation of that plate (i.e. plates were considered internally ‘rigid’, but with crust being accreted or destroyed at the plate boundaries). The kinematic models used in this paper use an adaptation of the continuously closing plates methodology to allow deformation within certain regions. Similar to the original continuously closing plates concept, the boundaries of deforming regions are built within GPlates from a series of lines and points. These lines and points have their own motion history such that the deforming regions can change geometry over time. However, within deforming regions, the plate velocities are not calculated from a single stage pole instead, they