Complex sentence: There is the argument that collision between two continents should slow down because of continental buoyancy, and that for convergence to continue, it should do so at a new subduction zone where oceanic crust can be consumed.
Split into simpler sentences: There is the argument that collision between two continents should slow down because of continental buoyancy. For convergence to continue, it should do so at a new subduction zone where oceanic crust can be consumed.