Benthische Foraminiferen als Proxies in Contourite Drift Systemen
Zusammenfassung der Projektergebnisse
Ocean circulation is a pivotal component of Earth’s climate system, largely determining the global distribution of heat and moisture. Understanding the behavior of oceanic circulation in climatic states analogous to predicted scenarios of climate change is thus of great interest. Crucial information can be inferred from fossil shells of benthic foraminifera, microscopic single-celled organisms living at the seafloor. A distinct group of species, termed the elevated epifauna (EEF), is of particular interest as its distribution is controlled by the intensity of bottom currents. Their abundances in the fossil record potentially provide a means (proxy) to determine the velocity of oceanic bottom currents in past climate states. The EEF is particularly abundant in contourites, sediments deposited by persistent bottom currents, off the Iberian Peninsula. There, this proxy has been successfully applied to the reconstruction of water mass exchange between the Mediterranean Sea and the Atlantic Ocean. The application to Contourite Drift Systems (CDSs) linked to the global conveyor belt of the thermohaline circulation is, however, problematic as baseline studies from key areas in the Atlantic Ocean are missing. Furthermore, contourites are often mixed with turbidites, sediments transported downslope from shallow waters by tectonic activity. Distinction of the two sediment types is not straightforward, yet the identification of compromised sediments determines the reliability of any paleoclimatic record. The reported project addressed these issues. The results contribute to an improved understanding of foraminifera-based proxy methods for the reconstruction of ocean circulation. The new data sets from CDSs at low, mid and high latitudes of the Atlantic Ocean demonstrate that the applicability of the EEF proxy cannot be generalized. Food availability, bottom current intensity, substrate properties and ecological heritage determine differential foraminiferal distributions within and between CDSs. The original concept has to be expanded by adding new groups of species adapted to bottom currents of different properties. The results provide important baseline studies for reconstructions of the thermohaline circulation in different climatic states of Earth’s past. The integration of new, highly resolved microfossil and sedimentological data from Pleistocene deposits of the Iberian Margin CDS shows that they carry complementary information on bottom current properties and contourite deposition. The data further demonstrate that abundances of displaced shallow water species provide means to easily distinguish contourites and turbidites. The determination of a shell’s source area by its geochemical fingerprint allowed the identification of EEF species particularly prone to displacement. Together, the data provide means of quality control for paleoclimatic archives from CDSs and improve our ability to understand ocean circulation in the past.
Projektbezogene Publikationen (Auswahl)
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Benthic Foraminifera in Contourite Drift Systems. Conference Abstract, TMS Joint Foraminifera and Nannofossil Meeting, Fribourg, Switzerland
Grunert, P.; Saupe, A. & Schmidt, J.
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Benthic Foraminifera as bottom current proxy in Contourite Drift Systems. Conference Abstract, IODP/ICDP Kolloquium 2020, Hamburg (cancelled on short notice due to pandemic)
Schmidt, J.; Saupe, A. & Grunert, P.
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Benthic foraminifera as tools to distinguish contourites and turbidites. Copernicus GmbH.
Schmidt, Johanna; Saupe, Anna; Petersen, Jassin; Bahr, André & Grunert, Patrick
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Biogeographic patterns of benthic foraminifera in contourite drift systems of the Atlantic Ocean. Conference abstract, GeoKarlsruhe 2021 (virtual conference)
Saupe, A.; Schmidt, J.; Petersen, J.; Bahr, A. & Grunert, P.
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Biogeographic patterns of benthic foraminifera in contourite drift systems of the Atlantic Ocean. Conference abstract, The Micropaleontological Society Foram Festival 2021
Saupe, A.; Schmidt, J.; Petersen, J.; Bahr, A. & Grunert, P.
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Biogeography of benthic foraminifera in contourite drift systems. Copernicus GmbH.
Saupe, Anna; Schmidt, Johanna; Petersen, Jassin; Bahr, André & Grunert, Patrick
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How to distinguish contourites and turbidites using benthic foraminifera. Conference abstract, The Micropaleontological Society Foram Festival 2021 (virtual conference)
Schmidt, J.; Saupe, A.; Petersen, J.; Bahr, A. & Grunert, P.
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The micropaleontological fingerprint on contourites and turbidites. Conference abstract, GeoKarlsruhe 2021
Schmidt, J.; Saupe, A.; Petersen, J.; Bahr, A. & Grunert, P.
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Controlling Parameters of Benthic Deep-Sea Foraminiferal Biogeography at the Brazilian Continental Margin (11-22°S). Frontiers in Marine Science, 9.
Saupe, Anna; Schmidt, Johanna; Petersen, Jassin; Bahr, André; Dias, Bruna Borba; Albuquerque, Ana Luiza Spadano; Díaz, Ramos Rut Amelia & Grunert, Patrick
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Understanding the taphonomic bias on the benthic foraminiferal bottom current proxy. Copernicus GmbH.
Schmidt, Johanna; Herwartz, Daniel; Saupe, Anna; Petersen, Jassin & Grunert, Patrick
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Benthic Foraminifera as Proxies in Contourite Drift Systems. Doctoral thesis, University of Cologne. External reviewer: G. Schmiedl, Hamburg
Saupe, A.
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Benthic foraminifera in high latitude contourite drift systems (North Atlantic: Björn, Gardar and Eirik drifts). Palaeogeography, Palaeoclimatology, Palaeoecology, 609, 111312.
Saupe, Anna; Schmidt, Johanna; Petersen, Jassin; Bahr, André & Grunert, Patrick
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Biogeography of benthic foraminifera in contourite drift systems. Conference abstract, FORAMS 2023, Perugia, Italy
Saupe, A.; Petersen, J.; Schmidt, J.; Bahr, A. & Grunert, P.
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Faunal composition and isotopic fingerprinting of benthic foraminifera to distinguish contourites from turbidites. Conference abstract, FORAMS 2023, Perugia, Italy
Schmidt, J.; Herwartz, D.; de Castro, S.; Hernández-Molina, J.; Petersen, J.; Saupe, A.; Bahr, A. & Grunert, P.
