Two‐Branch Break‐up Systems by a Single Mantle Plume: Insights from Numerical Modeling

Thermomechanical modeling of plume‐induced continental break‐up reveals that the initial location of a mantle anomaly relative to a lithosphere inhomogeneity has a major impact on the geometry and timing of a rift‐to‐spreading system. Models with a warmer Moho temperature are more likely to result in “plume‐centered” mode, where the rift and subsequent spreading axis grow directly above the plume. Models with weak far‐field forcing are inclined to develop a “structural‐inherited” mode, with lithosphere deformation localized at the lateral lithospheric boundary. Models of a third group cultivate two break‐up branches (both “plume‐centered” and “structural inherited”) that form consecutively with a few million years delay. With our experimental setup, this break‐up mode is sensitive to relatively small lateral variations of the initial anomaly position. We argue that one single mantle anomaly can be responsible for nonsimultaneous initiation and development of two rift‐to‐spreading systems in a lithosphere with a lateral strength contrast.