250 Ma, Pangea had just reached an equatorial position of dynamic
equilibrium, after a 60° northward migration due to True Polar
Wandering. It then began oscillating about itself for the next 150 Myr.
The resulting extensional stresses triggered three successive phases of
breakup, controlled by the mechanical resistance of a crescent of thick
lithosphere, surrounding the Tethyan realm, which had adjusted the
supercontinent to its hemispheric shape. The fracturing of the crescent
was produced in three successive generations, each new generation
corresponding to Coulomb fractures, conjugates of the preceding set.
Flood basalts were associated with these deep fractures within the thick
lithosphere crescent. We consider unlikely that this highly ordered
pattern of fracturing was determined by the locations of the impacts of
successive plumes. Between 260 and 180 Ma, thermal isolation was maximal
and the asthenosphere of Pangea was about 150°C warmer than below
Panthalassa. From 180 to 100 Ma, the breakup elongated Pangea by about 3
000 km in a NNW-SSE direction, producing gaps in the subduction girdle.
Lateral mixing began, leading to a continuous rise in global sea level
and progressive return to a globally homogeneous upper mantle with
sea-level at its maximum 100 Ma. This Cretaceous Revolution marked the
end of the Pangea tectonics, radically different from our present plate
tectonics. Neither post-Cretaceous plate kinematic inferences, nor
mantle dynamic and associated planetary cooling inferences are
extendable to Pangea times.