THE LOWER CRETACEOUS (BERRIASIAN AND VALANGINIAN) IN NW GERMANY

The non-marine sedimentary successions of the Berriasian and lower Val anginian of NW Germany are described. The stratigraphical distribution of ostracods allow this interval to be subdivided into 10 biozones, w hich can be used for regional correlation in the central part of the N W German Basin. Three ostracod taxa (Fabanella ansata, Cypridea alta f ormosa and Pachycytheridea compacta) can be used for interregional cor relation between Germany, Denmark, France and England. The middle parr of the Katzberg Member, which yields F. ansata, allows correlation wi th the Lower Purbeck of S England, the Paris Basin, and the Boulonnais . The first occurrence of this species can be used to define the Portl and/Purbeck boundary. Fluctuations in the taxonomic content of ostraco d assemblages reflect changes in salinity. Brackish conditions dominat ed deposition during the earliest Berriasian (Munder Formation) and ea rliest Valanginian (Osterwald Member). Sediments of the late Berriasia n Obernkirchen Member were deposited under freshwater conditions. A sh ort-lived marine transgression marked the mid Berriasian (base Wealden 4). The Platylenticeras Beds of mid-Valanginian age indicate a return to fully marine conditions. (C) 1996 Academic Press Limited