Pangaea and the Tethys: Importance of Strike-Slip Movements in Orogenic Development

Ever since proposed by Alfred L. Wegener the Phanerozoic Pangaea has been beset by various problems, the most important of which has been the palaeomagnetic mismatch of its two halves namely Laurasia in the north and Gondwana-Land in the south. Palaeomagneticians seem to agree that a placement of Gondwana-Land some 3000 km farther east than its conventional position would satisfy their data. Geologists, however, have been unable to find the necessary strike-slip systems, in fact whole keirogens, to bring Gondwana-Land to its conventional position just before the opening of the Atlantic Ocean. We here present data showing that the entire Hercynides, from the Appalachians to Eastern Europe, have been disrupted by very large strike-slip systems along which Gondwana-Land slid westward for some 2500–3000 km with respect to Laurasia. This ended up creating a vast, eastward-opening gap in the body of the Pangaea. This oceanic embayment is called Palaeo-Tethys. Palaeo-Tethys closed by a strip-continent, called the Cimmerian, that rifted from the northern margin of Gondwana-Land between the Permian and the Triassic from the Balkans to Thailand. It rotated anti-clockwise around a pole somewhere in the Balkans and collided with Laurasia creating the Cimmerides and opened behind it, in the form of a series of back-arc basins the Neo-Tethys. This explains why nearly all of the Neo-Tethyan ophiolites have the signature of supra-subduction zone creations. When Gondwana-Land fell apart during the Mesozoic and Cainozoic, its various pieces went to collide with the northern continent thus closing the Neo-Tethys and creating the Alpide orogenic system. All such collision events largely disrupted Eurasia creating very large strike-slip fault systems leading to the lateral escape of large chunks of continent away from the collision zone as, for example, in Tibet and Anatolia. We conclude that strike-slip faulting has played a much larger role in orogenic development since the Archaean than hitherto realised.