Rhizocorallium at omission surfaces on the southern edge of the Vocontian Basin (southeastern France): markers of local dynamics and their relation to a global anoxic event

On the North-Provence margin, an omission surface with Rhizocorallium often characterizes the sub-Aptian discontinuity between Eocretaceous carbonates and Aptian-Albian marls. This discontinuity is recorded in various success ions described along a palaeoslope joining the Vocontian Basin and the Prov ence platform, between the Jabron valley in the west and the Var valley in the east. The successions including Aptian marls always exhibit an omission surface with Rhizocorallium. Through this area, the Aptian discontinuity e quates to at least part of the Goguel Level. The latter is represented by b lack shales occurring in the Vocontian Basin at the top of Deshayesi zone a nd is a regional expression of the global anoxic event OAE1a. Thus, the sur face with Rhizocorallium can be regarded, on the North-Provence margin, as a marker coincident with the onset of the anoxic event which, in the Vocont ian basin, succeeded to a nannoconid crisis. Representing a short event, th e surface is also a marker of various processes: (1) current activity, dedu ced from a dominant orientation of Rhizocorallium. The Barremian - early Ap tian carbonate succession is strongly eroded by the formerly more active cu rrents along the Peipin Channel, south-east of Sisteron; these currents als o led to the omission of the Bedoulian (= carbonate Lower Aptian) to upper Valanginian series from the top of the hemipelagic palaeoreliefs in the eas tern Castellane are; (2) tectonic activity in the Lower Aptian, marked by N 080 degrees to N100 degrees extension faults and slumping of a semi-lithifi ed carbonate sediment. Slumped material and fault scarps are burrowed with Rhizocorallium; (3) differential lithification of the Barremian limestones which has led to distinctive types of current erosion.