Damyanovo Formation (new formation) in the Lower Cretaceous of the western fore-balkan (North-West Bulgaria)

A new formal lithostratigraphic unit - Darnyanovo Formation, is defined in the Lower Cretaceous sediments of NW Bulgaria. Its lower and middle part is composed of rhythmic flysch alternation of sandstones, siltstones and silty marls, whereas the upper part is built up by rhythmic thin packets of sandy limestones and calcareous sandstones. Damyanovo Formation is underlain by Mramoren Formation and is covered by Sumer Formation. Laterally, it passes to Sumer and Botunya Formations, and interfingers with Roman Formation. The chronostratigraphic range of the formation is Late Barremian - Late Aptian, based on ammonite and calcareous nannofossil finds. The deep-water turbiditic sediments of Damyanovo Formation are deposited in a depression of deficient sedimentation with slightly asymmetrical basin profile. They mark the final turbidite impulse in the geological development of the Early Cretaceous basin on the territory of North Bulgaria.