Upper Jurassic chalky limestones in the Zakrzówek Horst, Kraków, Kraków-Wieluń Upland (South Poland)

Chalky limestones in the Zakrzówek Horst were laid down in small sponge-microbolite biostromes that provided stable foundation for the growth of extensive sponge- ’’Tubiphytes ” biostromes forming the nodular limestones in the Zakrzówek area. The ammonites occurred in chalky limestones indicate that the studied deposits belong to the youngest palaentologically documented Upper Jurassic limestones in the Kraków area (Planula zone). The vertical succession of fauna and facies characteristics indicate progressive shallowing of the environment at the end Oxfordian, from deeper shelf to shallower water.