Geodynamic Evolution of the Tethyan Paleomargin of Oman

Guillocheau, François¹, Cecile Robin¹, Spela Gorican², francois Bechennec³, Philippe Razin⁴ (1) Géosciences Rennes, Université de Rennes-1, Rennes, France (2) Ljubjana University, Ljubjana, Slovenia (3) BRGM, Nantes, France (4) Bordeaux University, Bordeaux, France

An extensive sedimentological and stratigraphical (biostratigraphy and sequence stratig­raphy) study of the inverted Tethyan paleomargin of Oman has been carried out since five years. This starved carbonate margin is developed over a thinned continental crust now split into different tectonic nappes. Beyond the autochtonous Arabian platform and on an ocean­ward profile, those nappes are (1) the Sumeini unit, base of slope/ramp deposits, (2) the Hamrat Duru units, deep-sea plain sediments, (3) numerous paleo-tilted blocks, high at time of deposition (Sabt subunit, Al Aridh units – the most distal one) and (4) the Kawr unit (“Exotics”), seamounts on the oceanic crust. Numerous tectonic events are recorded on this paleomargin: (1) Tethys ocean opening (Permian), (2) Indian ocean opening (rifting phase: Trias-Jurassic boundary and Lower/Middle Jurassic boundary, drifting phase: uppermost Late Jurassic) and (3) Tethys ocean closure. The Late Jurassic event corresponds to a major deformation of the southeastern part of the Arabian plate, both in the shallow and the deep­sea record. One of the consequences is to increase the starvation of the turbiditic system. The consequences of those events on the paleogeography and the development of the deep­sea gravitational systems will be discussed, including the relationships with the shallow marine Arabian platform.