The role of surface processes in basin inversion and breakup unconformity

In the context of continental extension, transient compressional episodes (stress inversion) and phases of uplift (depth inversion) are commonly recorded with no corresponding change in plate motion. Changes in gravitational potential energy during the rifting process have been invoked as a possible source of compressional stresses, but their magnitude, timing, and relationship with depth inversions remain unclear. Using high-resolution two-dimensional numerical experiments of the full rifting process, we track the dynamic interplay between the far-field tectonic forces, loading and unloading of the surface via surface processes, and gravi-tational body forces. Our results show that rift basins tend to localize compressive stresses; they record transient phases of compressional stresses as high as 30 MPa and experience a profound depth inversion, 2 km in magnitude, when sediment supply ceases, providing an additional driver for the breakup unconformity, a well-documented phase of regional uplift typically associated with continental breakup.

Automated summary

This study investigates the formation mechanism of compressional episodes and phases of uplift during continental extension. The results show that rift basins tend to localize compressive stresses, with transient compressional stresses reaching up to 30 MPa. When sediment supply ceases, a profound depth inversion of 2 km magnitude occurs.