Danian cold-water corals from the Baunekule facies, Faxe Formation, Denmark: a rare taphonomic window of a coral mound flank habitat

Abstract

Well‐preserved cold‐water corals are comparatively rare in the fossil record. This is partly due to the very low fossilization potential of the predominantly aragonitic corals but also due to the fact that coral ecosystems of deep water are a geologically young development. A Middle Danian cold‐water coral mound complex is well exposed in Faxe Quarry, Denmark. The coral mounds are intercalated with bryozoan mounds of various sizes and form the Faxe Formation. The coral limestone displays large variations in diagenesis, and this complicates the palaeoecological reconstructions. However, the Baunekule facies from the Faxe Formation contain a well‐preserved originally aragonitic and calcitic fauna. The aragonitic skeletons have been recrystallized to calcite during early diagenesis and the excellent preservation makes taxonomic identifications straightforward. A diverse fauna of ten scleractinian coral species, nine stylasterine coral species and seven octocoral species has been described from the Baunekule facies. The fossil fauna represents an ecological niche between the dead coral framework and coral rubble on a flank of a growing Dendrophyllia coral mound with multiple colonization events. The diversity and relative abundance of the fossil scleractinian corals are comparable to the modern settings in the NE Atlantic and Mediterranean. The distribution and diversity of the octocorals and the stylasterine corals are suggested to represent coral gardens as described from modern setting in the NE Pacific. The presence of a diverse and abundant stylasterine fauna suggests a stable palaeoenvironment, probably in a bathymetric depth range of 200–400 metre.

Ecophenotypic asymmetry in the middle Danian brachiopodObliquorhynchia flustraceacaused by adaptation to attachment on the coralDendrophyllia candelabrum

“…Two million years after the K–Pg boundary, the coral mounds started to grow in deep water below the photic zone over the easternmost part of the Ringkøbing‐Fyn High, limiting the Danish Basin to the south (Floris ; Bernecker & Weidlich , ; Lauridsen et al . ; Lauridsen & Bjerager ).…”

Carbonate mounds: From paradox to World Heritage

“…Recent data suggest that the Faxe mounds of Danian age might have grown in depths of 200 to 400 m (Lauridsen and Bjerager, 2014). The third episode started recently, at the onset of Quaternary times.…”

“…Just after the K/Pg boundary carbonate platform sediments and small bryozoan mounds of Danian age are exposed in the Danish Basin at Stevns Klint (Surlyk, 1997;Bjerager and Surlyk, 2007). From mid-Danian non-symbiotic scleractinian coral mounds interbedded with low-diversity bryozoans mounds are exposed primarily in Faxe Quarry (Lauridsen et al, 2012;Lauridsen and Bjerager, 2014). The rise of modern-type coral-algal reefs was further underway in the Paleocene.…”

“…The Quaternary episode concurs with a well developed aragonite sea. Considering the occurrence of coldwater corals in Danian mounds (Lauridsen and Bjerager, 2014), the modern aragonite sea might have found its origin at the onset of the Tertiary. In terms of carbonate factory however, there barely could be a stronger contrast than between Carboniferous mounds and Quaternary ones.…”

Mound‐forming cold‐water corals and bryozoans in the Early Palaeocene of Denmark

“…Bottom currents were important for supplying particulate nutrients and for winnowing and reworking during the formation of the bryozoan and coral mounds that were major benthic carbonate factories in the Danian (Bjerager & Surlyk, ,b). The Faxe Quarry in south‐east Denmark exposes middle Danian deep‐water bryozoan and coral mounds dominated by the frame‐building corals Dendrophyllia candelabrum and to a lesser extent Faksephyllia faxoensis (Bernecker & Weidlich, ; Lauridsen & Bjerager, ).…”