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Astronomically paced changes in deep-water circulation in the western North Atlantic during the middle Eocene
- Source :
- EPIC3Earth and Planetary Science Letters, ELSEVIER SCIENCE BV, 484, pp. 329-340, ISSN: 0012-821X
- Publication Year :
- 2018
- Publisher :
- Elsevier BV, 2018.
-
Abstract
- North Atlantic Deep Water (NADW) currently redistributes heat and salt between Earth's ocean basins, and plays a vital role in the ocean-atmosphere CO2 exchange. Despite its crucial role in today's climate system, vigorous debate remains as to when deep-water formation in the North Atlantic started. Here, we present datasets from carbonate-rich middle Eocene sediments from the Newfoundland Ridge, revealing a unique archive of paleoceanographic change from the progressively cooling climate of the middle Eocene. Well-defined lithologic alternations between calcareous ooze and clay-rich intervals occur at the ∼41-kyr beat of axial obliquity. Hence, we identify obliquity as the driver of middle Eocene (43.5–46 Ma) Northern Component Water (NCW, the predecessor of modern NADW) variability. High-resolution benthic foraminiferal δ 18 O and δ 13 C suggest that obliquity minima correspond to cold, nutrient-depleted, western North Atlantic deep waters. We thus link stronger NCW formation with obliquity minima. In contrast, during obliquity maxima, Deep Western Boundary Currents were weaker and warmer, while abyssal nutrients were more abundant. These aspects reflect a more sluggish NCW formation. This obliquity-paced paleoceanographic regime is in excellent agreement with results from an Earth system model, in which obliquity minima configurations enhance NCW formation.
- Subjects :
- geography
geography.geographical_feature_category
010504 meteorology & atmospheric sciences
Lithology
North Atlantic Deep Water
010502 geochemistry & geophysics
01 natural sciences
Boundary current
Deep water
Abyssal zone
Paleontology
Geophysics
13. Climate action
Space and Planetary Science
Geochemistry and Petrology
Benthic zone
Earth and Planetary Sciences (miscellaneous)
Earth system model
14. Life underwater
Oceanic basin
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 0012821X
- Volume :
- 484
- Database :
- OpenAIRE
- Journal :
- Earth and Planetary Science Letters
- Accession number :
- edsair.doi.dedup.....c2fe7d872ec7831dec602ec3213a544b