Premiere datation par ammonite et brachiopodes du Tithonien au Saleve (Haute-Savoie France), consequences sur l'interpretation stratigraphique de paleogeographique du Jurassique superieur

The oldest beds outcropping in the Mt Saleve have in the past been referred to the Kimmeridgian, bur an ammonite found in situ together with some brachiopods give them a date somewhere in the middle part of the Lower Tithonian. Recently published interpretation of the local Upper Jurassic stratigraphy and relationship to the Jura platform have therefore to be revised. The Upper Jurassic succession at Saleve is distinguished by a Tithonian continuation of a carbonate platform facies prograding basinward, which compares well with the similar well-known Bec de l'Echaillon, near Grenoble. An erosional disconformity, related by other authors to a fall in relative sea-level and interpreted as a type I sequence boundary associated with a large emergence of the Jura platform, cannot be referred to the Kimmeridgian-Tithonian and must lie somewhere in the Lower Tithonian recks above the Gravesia beds.