DEPOSITIONAL SEQUENCE PROCESSES OF THE BATHONIAN TRANSGRESSION OVER THE CEVENNES-SHOAL (GRANDS-CAUSSES, FRANCE)

In the Grands Causses area, the Bathonian series is subdivided into 4 depositional sequences, Bt 1 to Bt 4, within the Middle Bathonian-Uppe r Bathonian interval. Their maximum flooling surfaces (Mfs) are marked by brachiopod-bearing levels allowing new datings. The stacking of th e 4 sequences is observed along the axis of the ''Grands Causses Grabe n'' (Gorges du Tarn). Towards the S-SE, Bt 3 and Bt 4 overlap Bt 1 and Bt 2 and directly overlie various older Jurassic formations covering the NW steps of the ''Cevennes Shoal''. This transgression is induced by the spatial displacement of subsidence which is restricted in the g raben for the first two sequences, then becomes generalized over the w hole Grands Causses realm for the latter two.