Numerical Modeling of Purely Active (Plume‐Produced) Continental Rifting and Break‐Up

Abstract In contrast to the traditional mechanism of passive continental rifting (driven by far‐field tectonic forces), the active rifting‐to‐break‐up processes (caused by rising mantle plumes) are still poorly understood. However, most episodes of fragmentation of the last supercontinent Pangea were relatively shortly preceded (within ∼10 Myr) by the emplacement of Large Igneous Provinces, indicating that a link between lithospheric ruptures and mantle plumes is very close and frequent. In this study, we present a systematic numerical modeling of purely active continental rifting and break‐up, that is, without far‐field extension, examining the following parameters: (a) the thermo‐rheological structure of the lithosphere, (b) the buoyancy of the thermo‐chemical mantle plume anomaly, and (c) the duration of the incoming plume flux. Thermo‐mechanical experiments show that a classic active rifting scenario, involving the complete break‐up of the lithosphere within less than 10 Myr following the arrival of a mantle plume, is achievable, though only under specific conditions. These include: (a) a continuously fed plume with an elevated thermal and/or compositional density deficit ( ≤ −30 kg m −3 ) and (b) a relatively warm overlying continental plate, characterized by an above‐average Moho temperature ( = 750°C). Although both prerequisites do not seem entirely unrealistic, their simultaneous occurrence in the Phanerozoic Earth is unlikely. We therefore conclude that for a successful transition to lithospheric break‐up, plume‐activated continental rifting events in the Mesozoic–Cenozoic time must be accompanied by external tectonic stresses.