Mid-ocean ridge extinctions as amplifiers of plate-tectonic reorganizations

Plate-tectonic reorganizations are characterized by rapid shifts in plate motions, boundary forces, and margin tectonics, yet the role of mid-ocean ridge extinctions (MOREs) during these events remains poorly constrained. We address this gap by systematically examining a suite of MOREs occurring within plate reorganizations and by comparing them with strength-profile analyses of thermally evolving oceanic lithosphere beneath spreading axes following spreading shutdown. Thermal models and strength-envelope calculations show that extinct ridges undergo rapid lithospheric strengthening, developing sufficient mechanical resistance to transmit slab-pull stresses within ~2–10 Myr after spreading cessation. This rapid welding transforms formerly weak ridge–transform networks into coherent lithospheric blocks capable of mediating far-field stress transfer. We illustrate this process using three well-constrained Cenozoic MOREs. Extinction of the Wharton Ridge promoted Indo–Australian plate welding and enhanced slab pull along the Sunda–Java trench, accelerating plate motion and sustaining post-collisional India–Asia convergence. Progressive shutdown of Pacific–Farallon ridge fragments enabled coupling between the Pacific and North American plates and facilitated subsequent Pacific stress transmission, driving deformation in the Gulf of California rift and the San Andreas system. In the western Pacific, cessation of the Shikoku Ridge strengthened the Philippine Sea Plate, enabling efficient transmission of slab pull in the Ryukyu–Nankai/Izu–Bonin–Mariana double subduction system and triggering trench advance and regional compressional tectonics in northeast Japan. Our results indicate that MOREs act as active amplifiers of plate reorganizations by enhancing lithospheric coupling and facilitating far-field stress propagation. These findings support a cascading, plate-to-plate mode of tectonic reorganization (rather than mantle-driven) and highlight extinct ridges as critical nodes in the episodic reorganization of the global plate network. Building on these insights, we extend the discussion to the Paleozoic–Mesozoic Tethyan system, where successive terrane collisions and episodes of subduction initiation may likewise have involved MOREs acting as stress transmitters across ridge–transform networks.