The effect of inheritance, rheology, and stress orientation on the 4-D evolution of rift systems

Continental rifts often show a complex spatial and temporal evolution, controlled by the intricate interaction of several ingredients. Inheritance, plate rheology, and stress orientation are amongst the main factors that shape rifts and dictate their fate. In this contribution, we use observations from two rift systems – i.e., the Labrador Sea and the Atlas System – to constrain 3D geodynamic models and assess the role of inherited structures, rheological heterogeneities, stress field (re-) orientation and obliquity on rift evolution.

The Labrador Sea formed as a branch of the North Atlantic Ocean, which propagated across major Precambrian suture zones. The subsequent rifted margins show striking lateral changes in the structural architecture, the crustal geometry, and the magmatic budget during breakup. Our geophysical data analysis and 3D geodynamic models suggest that pre-rift rheological changes in the lithosphere (i.e., composition, thickness, and thermal structure) dominated the rifting process and the ensuing continental breakup.   

The Atlas fold and thrust belt is a failed rift system that evolved in Mesozoic times and was inverted in the Cenozoic. The rifting phase was driven by two concurrent extensional stress fields linked to the coeval opening of two highly oblique oceans: the Central Atlantic and the Tethys. Here, our 3D geodynamic models constrained by field observations highlights the importance of the pre-rift structural template in dictating the strain distribution/localization, the lithospheric extension mode (i.e., orthogonal rifting vs. transtension), and the location of magmatism.