DEPOSITIONAL SEQUENCES IN DEEP-SHELF ENVIRONMENTS FORMED THROUGH CARBONATE-MUD IMPORT FROM THE SHALLOW PLATFORM (LATE OXFORDIAN, GERMAN SWABIAN ALB AND EASTERN SWISS JURA)

Upper Oxfordian deposits in southern Germany exhibit limestone-mart al ternations typical of deep-shelf depositional environments. These depo sits contain varying amounts of brachiopods, echinoderms, foraminifera (mainly represented by Spirillina, Lenticulina, Usbekistania, Bigener ina Glomospira and Reophax), cephalopods? sponges and associated encru sters, and scarce bivalves, ostracods and gastropods. Fragments of rew orked microbialites (tuberoids, Tubiphytes, nubecularians, bryozoans, serpulids, and Terebella), and glauconite also occur in variable quant ities. In one section of the proximal shelf area (eastern Swiss Jura) there is interfingering of facies dominated by platform-derived elemen ts (ooids, oncoids, coral fragments, peloids, bivalves, ostracods, gas tropods) and of facies related to a more parautochthonous, distal sedi mentation (Rhaxella and other sponge-spicules, brachiopods, Lenticulin a, Spirillina). The complete record of each ammonite zone as well as t he recognition of different ammonite horizons suggest that no importan t sedimentary gap is present For the deep-shelf deposits of southern G ermany, statistical analysis shows that the higher the total percentag e of particles is in a sample, the more frequent are glauconite, biotu rbation, nodularization, cephalopods, sponges, and microbial crusts. W ackestone and packstone samples thus generally correspond to lower sed imentation rates than mudstones that reflect a high carbonate-mud sedi mentation rate. The carbonate mud is thought to be exported from the s hallow platform because scarce nannofossils and/or insignificant bioer osion in sponge reefs exclude the possibility of relating carbonate-mu d variations to changes in autochthonous productivity. Variation in ca rbonate-mud exportation from the platform towards the deep shelf has t hus been implied from the relative abundance of particulate elements ( fauna, tuberoids) which are considered as mainly autochthonous or para utochthonous. Consequently, changes in carbonate mud content in the st udied deep-shelf settings may be related to carbonate production on th e shallow platform and to the export dynamics from the platform to dee per sedimentary environments. Variation in carbonate sedimentation rat e has been used to interpret depositional sequences in terms of sequen ce stratigraphy and cyclostratigraphy: constrained by a detailed bio- and chronostratigraphical framework, a correlation of these sequences is proposed between the sections in southern Germany and the eastern S wiss Jura.