The Impact of Orogenic Inheritance on Rifted Margin Formation

Résumé fourni par la source

Abstract Many rifted margins form within pre‐existing orogenic belts, emphasizing the significance of structural, thermal, and compositional inheritance in shaping rift dynamics. However, a key unresolved question is how these different types of orogenic inheritance individually influence rift evolution. This study employs numerical modeling to simulate rift evolution in homogeneous lithosphere and in contraction–extension models incorporating pre‐existing orogens. The novelty of our approach lies in isolating the impact of inherited structures: (a) The role of structural inheritance is analyzed by comparing model results with and without inherited thrust faults. (b) The impact of thermal inheritance is isolated by comparing models with and without a tectonic‐quiescence period following orogeny, during which erosion modifies topography and thermal relaxation occurs. We find that models with orogenic inheritance require lower external forces for rift initiation, exhibit delayed continental breakup, and form wider rifted margins than models with homogeneous initial conditions. Structural inheritance, characterized by localized loss of cohesive and frictional strength, predominantly controls the required rift initiation forces, margin width and breakup location. Thermal inheritance governs crust‐mantle coupling, significantly influencing rift migration, breakup timing, and margin symmetry. Furthermore, we find that the impacts of structural and thermal inheritance become increasingly pronounced in models with lower strengths. Conversely, in strong lithosphere models, compositional inheritance from inherited rheological interfaces consistently dominates, producing asymmetric rifted margins. These quantitative results, supported by numerical experiments and geological observations, establish a unified framework for understanding how different types of orogenic inheritance govern the evolution and global variability of rifted margins.

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