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Gröger, Matthias; Henrich, Rüdiger; Bickert, Torsten (2003): Planktonic foraminiferal preservation in Plio/Pleistocene sediments from the western equatorial Atlantic and Caribbean [dataset publication series]. PANGAEA,, Supplement to: Gröger, M et al. (2003): Variability of silt grain size and planktonic foraminiferal preservation in Plio/Pleistocene sediments from the western equatorial Atlantic and Caribbean. Marine Geology, 201(4), 307-320,

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Records of mean sortable silt and planktonic foraminiferal preservation from the Ceará Rise (western equatorial Atlantic) and from the Caribbean are presented to analyze the Pliocene (3.5-2.2 Ma) to Pleistocene (1.6-0.3 Ma) evolution of near-bottom current strength and the carbonate corrosiveness of deep water. During the mid-Pleistocene climate transition (~1 Ma) a drastic decrease in glacial bottom current strength and an increase in carbonate corrosiveness is registered, demonstrating a substantial decrease in the glacial contribution of the Lower North Atlantic Deep Water (LNADW) to the Atlantic Ocean. Also, an increased sensitivity to eccentricity orbital forcing is registered after the MPT. By contrast, carbonate preservation increases considerably in the deep Caribbean in response to a strong and persistent stable contribution of Upper North Atlantic Deep Water (UNADW). We found evidence for the strongest and most stable circulation within the LNADW cell during the Northern Hemisphere cooling period between ~3.2 and 2.75 Ma. This is in agreement with the 'superconveyor model' which postulates that the highest NADW production took place prior to ~2.7 Ma. A considerable decrease in bottom current strength and planktonic foraminiferal preservation is observed synchronous with the first occurrence of large-scale continental ice sheets in the Northern Hemisphere. This documents the final termination of the 'superconveyor' at ca. 2.75 Ma. However, our data do not support a 'superconveyor' in the interval between 3.5 and 3.2 Ma when high-amplitude fluctuations in bottom current flow and preservation in planktonic foraminifera are observed. Because of the great sensitivity of NADW production to changes in surface water salinity, we assume that the high-amplitude fluctuations of LNADW circulation prior to ~3.2 Ma are linked to changes in the Atlantic salinity budget. After 2.75 Ma they are primarily controlled by ice-sheet forcing. In contrast to the stepwise deterioration of planktonic foraminiferal preservation in the western deep Atlantic, a trend toward better preservation from the Pliocene to Pleistocene is observed in the deep Caribbean. This indicates a long-term increase in the contribution of UNADW to the Atlantic Ocean.
Related to:
Gröger, Matthias (2002): Deep-water circulation in the western equatorial Atlantic: inferences from carbonate preservation studies and silt grain-size analysis. Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen, 195, 95 pp, urn:nbn:de:gbv:46-00103059-12
Median Latitude: 9.103330 * Median Longitude: -61.609900 * South-bound Latitude: 5.462660 * West-bound Longitude: -78.739300 * North-bound Latitude: 12.744000 * East-bound Longitude: -44.480500
Date/Time Start: 1994-02-28T06:30:00 * Date/Time End: 1996-01-14T23:15:00
154-927A * Latitude: 5.462660 * Longitude: -44.480500 * Date/Time Start: 1994-02-28T06:30:00 * Date/Time End: 1994-03-01T15:54:00 * Elevation: -3325.0 m * Penetration: 312.5 m * Recovery: 315.79 m * Location: South Atlantic Ocean * Campaign: Leg154 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 312.5 m cored; 0 m drilled; 101.1 % recovery
165-999A * Latitude: 12.744000 * Longitude: -78.739300 * Date/Time Start: 1996-01-10T19:30:00 * Date/Time End: 1996-01-14T23:15:00 * Elevation: -2828.0 m * Penetration: 566.1 m * Recovery: 534.83 m * Location: Caribbean Sea * Campaign: Leg165 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 61 core; 566.1 m cored; 0 m drilled; 94.5 % recovery
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