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The micropaleontological fingerprint on contourites and turbidites

Bottom current-induced sediments such as contourites contain fundamental information for reconstructions of water mass properties and ocean circulation. The distinction between contourites and other deposits on continental slopes is particularly complex in areas where downslope and along-slope sedimentary processes co-occur. Clear and easily applicable diagnostic criteria for properly distinguishing between contourites and other coarse-grained and/or graded deep-water deposits such as turbidites are still limited (e.g., de Castro et al., 2020) and mainly focus on sedimentological data. The present study investigates Pleistocene contouritic (~0.5 Ma) and turbiditic (~0.9 Ma, ~1.1 Ma) sequences from the SW Iberian Margin in the Gulf of Cádiz (IODP Site U1389), where thick contourite drift bodies with extensively intercalated turbidites are preserved (Stow et al., 2013). The aim of the study is to define diagnostic criteria based on benthic foraminiferal assemblage composition in order to differentiate between normally graded contourites and turbidites as well as reworked turbidites. The revealed “foraminiferal fingerprint” will allow for improving paleoceanographic interpretations of sedimentary archives from complex depositional environments along continental margins. References: De Castro, S., Hernández-Molina, F.J., de Weger, W., Jiménez-Espejo, F.J., Rodríguez-Tovar, F.J., Mena, A., Llave, E., Sierro, F.J., 2020. Contourite characterization and its discrimination from other deep‐water deposits in the Gulf of Cadiz contourite depositional system. Sedimentology. Stow, D.A.V., Hernández-Molina, F.J., Llave, E., Bruno, M., García, M., Díaz del Rio, V., Somoza, L., Brackenridge, R.E., 2013. The Cadiz Contourite Channel: Sandy contourites, bedforms and dynamic current interaction. Mar. Geol. 343, 99–114.


Johanna Schmidt1, Anna Saupe1, Jassin Petersen1, André Bahr2, Patrick Grunert1
1University of Cologne, Faculty of Mathematics and Natural Sciences, Institute of Geology and Mineralogy, Zülpicher Str. 49a, 50674 Cologne, Germany; 2Heidelberg University, Faculty of Chemistry and Earth Sciences, Institute of Earth Sciences, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany
GeoKarlsruhe 2021