Benthic foraminifera inhabit diverse marine environments, including areas of persistent bottom currents and contourite drift deposition. Certain highly adapted epibenthic foraminifera colonize contourite deposits as opportunistic suspension feeders. A correlation between these assemblages and high bottom current velocities has been highlighted in previous studies from the Iberian Margin (e.g. Schönfeld, 2002), suggesting their applicability as reliable proxy for reconstructing bottom currents.
Our ongoing project aims to document biogeographic patterns of benthic foraminifera from extended contourite drift systems in the Atlantic Ocean. The results will provide a framework to evaluate the applicability of foraminifera-based proxy methods for reconstructing bottom currents in different Atlantic contourite deposits. Existing data from the mid-latitude Iberian Margin are complemented by new faunal data from surface samples at high (50-62°N; Björn and Gardar Drifts, Iceland Basin; Eirik Drift, southern Greenland Margin) and low latitudes (10°-22°S Campos Drift, Brazilian Margin).
Preliminary results show variations in faunal composition along gradients of current intensity. Low current velocities at Björn and Gardar Drifts (max. 10 cm/s) favor tubular agglutinated taxa such as Rhabdammina abyssorum and Saccorhiza ramosa. An association of hyaline attached species including Cibicides refulgens and Cibicidoides wuellerstorfi preferentially settle in intermediate flow speeds at the Eirik Drift (12-22 cm/s). Communities of Campos Drift dwell at higher current velocities (up to 80 m/s) and show increased abundances of Cibicides lobatulus, Globocassidulina subglobosa, and Planulina ariminensis.
Schönfeld, J., 2002. Recent benthic foraminiferal assemblages in deep high-energy environments from the Gulf of Cadiz (Spain). Mar. Micropaleontol. 44, 141–162. https://doi.org/10.1016/S0377-8398(01)00039-1
Anna Saupe1, Johanna Schmidt1, Jassin Petersen1, André Bahr2, Patrick Grunert1
1University of Cologne, Institute of Geology and Mineralogy, Germany; 2Heidelberg University, Institute of Earth Sciences, Germany