Jean-Marc Marion

New data on the incertae sedis biota and foraminifera of the mid-Famennian Baelen Member (Late Devonian, eastern Belgium)

The Baelen mud mounds in eastern Belgium represent a local member of the mid-Famennian Souverain-Pré Formation (an important carbonate interval within the Condroz Sandstone Group). The lower part of this member contains silty bioclastic wackestones and packstones that are particularly rich in the problematical protists Serrisinella and Dreesenulella. Plurilocular foraminifera (Septabrunsiina and Baelenia) and rare solitary rugose corals (Neaxon? sp.) occur within crinoidal grainstones (tempestites) interfingering with the latter bioclastic wacke-/packstones and with red-stained stromatactoid spiculitic mudstones (carbonate mud mound core facies). Although Serrisinella is quite common in other mid-Famennian limestones of Belgium, Dreesenulella is almost endemic of the Baelen Member. Both genera apparently inhabited the muddy sediment-water interface, constituting meadows probably in zones of intermittently strong bottom currents. The taxonomic similarities between Dreesenulella and Saccamminopsis are discussed, as well as their possible affinities with the Xenophyophora and Kokomiacea. The first stages of the Septabrunsiina–Baelenia foraminiferal lineage are analysed in detail. The taxonomic and palaeoecological positioning of Serrisinella and Dreesenulella adds to the discussion about the palaeobathymetry of the Baelen mud mounds and corroborates sedimentological evidence for their relatively shallow carbonate ramp depositional setting.