The superposed orogenesis of the alpine-mediterranean edifice

Abstract

The circum-Mediterranean chains must be considered as the result of two distinct orogenies. The apparent unity of the present structure is of formal order, due to the latest deformations. Since the Hercynian time there have been two periods of paroxysmal deformation; the younger fits the definition of the alpine orogeny; the older occurred during the Cretaceous and may correspond to the first great convergent relative drift of the Eurasiatic and African blocks. The Cretaceous or Mesogean orogeny is independent from the Alpine orogeny stricto sensu (Oligo-Miocene) and cannot be considered as its prefiguration. Being independent in time, it is independent in space as well. Even if this Mesogean orogeny can appear locally restricted to the ‘’internal’’ parts of the Alpine chains (Central Mediterranean area, Carpathes, Dinarides) this cannot be taken as a rule: towards the west, the Cretaceous deformations cross the axis of the western Alps and extend (new investigations) over Provence to the Betic chains and the Pyrenean area. Towards the east, the deformations of this period cross the Hellenides (new observations) and spread over the ‘’external’’ area in a spectacular way, interesting areas which have never been tectonised again (Cyprus, south-eastern Anatolia, northern Syria, Oman). As a whole, this large Cretaceous orogenic zone is part of a wider domain which extends over central Iran towards the Himalayas and eastern Asia, and has its equivalent on the western side of the Atlantic Ocean, in the Caribbean islands, Mexico and the Americas.