The middle Danian Faxe Formation – new lithostratigraphic unit and a rare taphonomic window into the Danian of Denmark

Abstract

The new middle Danian Faxe Formation is defined on the basis of the succession exposed in the large Faxe quarry in eastern Denmark. The formation is defined as a distinct mappable ithostratigraphic unit of interfingering coral and bryozoan limestone passing laterally into bryozoan limestones of the Stevns Klint Formation. The Baunekule facies is recognized in the upper part of the coral mound complex of the Faxe Formation, where it forms isolated lensoidal bodies in the flanks of some of the coral mounds. It is characterised by a high diversity invertebrate fauna with both calcite and originally aragonite-shelled benthic invertebrates set in weakly consolidated coral-dominated floatstone to rudstone. The diagenesis of the Baunekule facies is of special significance because a high proportion of the originally aragonite-shelled fauna is preserved by recrystallization to calcite during early burial diagenesis. More than 80% of the species from the Baunekule facies are unknown from other parts of the Faxe Formation. The carbonate mud matrix is only slightly consolidated and the invertebrate fossils are accordingly easy to prepare in contrast to the fossils from the lithified parts of the Faxe Formation, which are commonly only preserved as moulds or casts. The facies therefore presents an exceptional taphonomic window into a cold-water coral mound fauna, giving an unusually complete picture of the diversity and density of the shelly invertebrate fauna.