Cyclical one-way continental rupture-drift in the Tethyan evolution: Subduction-driven plate tectonics

Abstract

Numerous continents have rifted and drifted away from Gondwana to repeatedly open ocean basins over the past ~500 million years. These Gondwana-derived continents drifted towards and collided with components of the Eurasian continent to successively close the preexisting oceans between the two. Plate tectonics satisfactorily describes the continental drift from Gondwana to Eurasia but does not define the geodynamic mechanism of continuously rifting to collisions of continents in the Tethyan Realm. After reappraisal of geological records of the rift, collision and subduction initiation from the surface and various geophysical observations from depth, we propose that Eurasia-directed subducting oceanic slabs would have driven Tethyan system in the Phanerozoic. The Eurasia-directed subduction would have dragged the passive Gondwana margin to rift and drift northwards, giving birth to new oceans since the Paleozoic. The closure of preexisting oceans between the Gondwana-derived continents and Eurasia led to continental collisions, which would have induced the initiation of oceanic subduction in the Tethyan Realm. Multiple episodic switches between collision-subduction-rift repeatedly led to the separation of continental fragments from Gondwana and dragged them to drift towards Eurasia. The final disappearance of Neo-Tethys would have induced collision of the Gondwana-derived continents with the Eurasian continent, giving rise to the Cenozoic Alpine-Zagros-Himalayan collisional system. Therefore, the Eurasia-directed oceanic subduction would have acted as a ‘one-way train’ that successively transferred the ruptured Gondwana continental fragments in the south, into the terminal in the north. In this regard, the engine of this “Tethyan one-way train” is the negative buoyancy of subducting oceanic slabs.