Plume-Induced Breakup of a Subducting Plate: Microcontinent Formation Without Cessation of the Subduction Process

Separation of microcontinents is explained by a ridge jump toward the passive margin as a possible consequence of plume-induced rheological weakening, ultimately leading to breakup followed by accretion of the oceanic crust along a new spreading center. In contrast to such a purely extensional case, the separation of continental microblocks from the main body of the African plate during its continuous northward motion and subduction under Eurasia is still poorly understood. Our numerical experiments show the thermal and buoyancy effects of mantle plume impingement on the bottom of the continental part of a subducting plate are sufficient to induce separation of an isolated microcontinental block from the main subducting continent, even during induced plate motion necessary for uninterrupted oceanic and continental subduction. Subsequent continental accretion occurs by decoupling upper-crustal nappes from the newly formed subducting microcontinent, which is in agreement with the Late Cretaceous-Eocene evolution of the eastern Mediterranean.