Figure 6. Subfigure A illustrates how Tharsis-driven extension
in Bathys Planum might reactivate an antecedent basement fault (black)
as a strike-slip fault, causing the observed stairstepping graben
morphologies. Green illustrates both the graben and the direction of
extension (σ3) implied by the graben’s formation. When
the graben intersects with the antecedent structure, the same regional
stress field drives a component of throw and heave (in green,
perpendicular to the structure) and a component of left-lateral motion
(in black, parallel to the structure) that causes similar lateral
deformation elsewhere on the fault, driving the aforementioned
stairstepping morphologies. Subfigure B shows the mapped faults (other
than graben) without the basemap to highlight the curvilinear form of
faults.