Oblique continental rifting. Insights from 3-D forward coupled geodynamic-surface process modelling and application to the Equatorial passive margins formation.

Continental rifting is often oblique to the rift axis or plate boundary, comprising many active rifts and mature rifted margins on Earth. Previous research has identified the role of vertical strike-slip and transform structures in oblique extension but has also shown that the initiation of long-distance syn-rift vertical strike-slip motion requires preexisting weaknesses. The Southern part of the Equatorial passive rifted conjugate margins is a typical example that exhibits orthogonal rift segments separating with transform faults with different lengths and orientation. We aim in this study to 1) understand the influence of these inherited weaknesses on the pattern of faulting, 2) to evaluate the consequences of oblique margin formation for rift related topography, and 3) to explore the interaction between tectonic and surface processes in the context of oblique rifting. We use most recent advances in 3-D forward geodynamic modeling coupled with surface processes. Preliminary results support the importance of inherited weak zones in shaping segmented oblique continental margins, with highly contrasting tectonic and subsidence histories in the orthogonal and transform segments. These results compare well with observations from the Equatorial passive rifted conjugate margins and provide insight into the factors that may drive the timing and magnitude of vertical motions and associated sediment flux.