Integrated Lower Cretaceous biostratigraphy of the Bersek Quarry, Gerecse Mountains, Transdanubian Range, Hungary

An integrated biostratigraphic subdivision, on the basis of ammonites and belemnites, is proposed for the Lower Cretaceous siliciclastic succession of the Bersek Quarry (Gerecse Mountains, Hungary). Rich ammonite faunas permit recognition of many of the recently established Mediterranean ammonite zones, from the upper Valanginian Varlheideites peregrinus Zone to the lowermost upper Barremian Toxancyloceras vandenheckii Zone. Associations of the diverse belemnite fauna allow subdivision at the substage level and are correlated with the ammonite biostratigraphy of the marlstone-sandstone succession. Many of the recognised cephalopod species are documented for the first time from Hungary. A thick succession of lower Valanginian strata that crop out in the lower part of the quarry yielded no cephalopods, hampering detailed zonation. The biostratigraphically well-documented succession of the Bersek Quarry will serve as a key section for the Mediterranean Lower Cretaceous.