Atlantic Ocean circulation during the latest Cretaceous and early Paleogene; progressive deep water exchange

Author(s): Batenburg, S. J.; Voigt, S.; Friedrich, O.; Frank, M.
Author Affiliation(s): Primary:
Goethe University Frankfurt, Institut für Geowissenschaften, Frankfurt, Germany
University Heidelberg, Institut für Geowissenschaften, Heidelberg, Germany
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Atlantic deep ocean circulation in the Latest Cretaceous (75-66 Ma) was dominated by regional processes, as indicated by the presence of distinct deep water masses. Due to the opening of the Atlantic Ocean, its different sub-basins became progressively connected and a global mode of ocean circulation commenced in the early Paleogene, ≈60 Ma. To understand the evolution of deep water formation and exchange, Nd-isotope data and δ13C stratigraphies are generated for a range of sites in the North and South Atlantic. These permit to identify different intermediate and deep-water masses, to recognize their potential source regions and to determine the exact timing of deep water connection. The carbonate-rich pelagic sediments of Site U1403 near Newfoundland can be astronomically tuned and correlated to the global δ13C framework. Relatively negative seawater εNd(t) signatures in the 67-62 Ma interval at Site U1403 of ≈-10 are distinct from those recorded further south in the North Atlantic. Possible explanations could include elevated non-radiogenic weathering inputs from the North American craton. In the latest Maastrichtian, the Site U1403 εNd(t) record displays a short-term positive excursion before the K/Pg boundary (67-66 Ma) followed by a sudden drop to unradiogenic values at the boundary. Changes in ocean circulation might be related to climatic changes in the pre-extinction interval and the impact itself. The εNd(t) records at Sites 1267 and 525 at Walvis Ridge show that an early Maastrichtian excursion to highly radiogenic values reflects a brief interval at 72-70 Ma, related to a period of increased hot-spot volcanism. Concomitant measurements of εNd(t) values in three different archives, fish teeth, ferromanganese coatings of bulk sediments and of foraminifera, provide a test for the partial influence of detrital particles on the isotopic composition of coatings. The first data of Sites U1403, 1267 and 525 indicate the occurrence of a common deep-water neodymium isotope signature (εNd(t) -8) in the North and South Atlantic since 60 Ma. At this time, the sub-basins of the deep Atlantic became fully connected. A deep-water mass with a common εNd(t) signature, likely originating in the high southern latitudes, prevailed over a broad range of water depths, indicating vigorous deep ocean circulation.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Cretaceous; Expedition 342; IODP Site U1403; Integrated Ocean Drilling Program; Lower Paleogene; Mesozoic; North Atlantic; Ocean circulation; Paleo-oceanography; Paleogene; Tertiary; Upper Cretaceous
Coordinates: N395636 N395636 W0514811 W0514812
Record ID: 2015106267
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