Suborbital intermediate water variability inferred from paired benthic foraminiferal Cd/Ca and δ13C in the tropical West Atlantic and linking with North Atlantic climates
Paired benthic Cd/Ca and δ13C records have been generated along core M35003 in the western tropical Atlantic. Decreased glacial water column dissolved cadmium (Cdw) and increased benthic δ13C indicate enhanced ventilation with nutrient-deplete intermediate waters, in line with similar inferences fro...
Published in: | Earth and Planetary Science Letters |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier
2002
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Subjects: | |
Online Access: | https://oceanrep.geomar.de/id/eprint/33343/ https://oceanrep.geomar.de/id/eprint/33343/1/Zahn_EPSL.pdf https://doi.org/10.1016/S0012-821X(02)00613-1 |
Summary: | Paired benthic Cd/Ca and δ13C records have been generated along core M35003 in the western tropical Atlantic. Decreased glacial water column dissolved cadmium (Cdw) and increased benthic δ13C indicate enhanced ventilation with nutrient-deplete intermediate waters, in line with similar inferences from other North Atlantic mid-depth records. An abrupt early deglacial δ13C collapse that is associated with a marked positive Cdw anomaly indicates a transient collapse of mid-depth ventilation from North Atlantic sources, conceivably in conjunction with the H1 meltwater anomaly. The Cdw record displays fine-scale fluctuations that mimic the Greenland Dansgaard/Oeschger (D/O) cycles and show decreased Cdw during stadials. This pattern is opposite to Cdw variations in a deep water record from Bermuda Rise that display increased Cdw concentrations during stadials. The divergent pattern between mid-depth and deep water Cdw records indicates millennial-scale switches between deep and shallow convection in the glacial North Atlantic, at the pace of the D/O climatic cycles. Several high-amplitude anomalies occur in the Cdw record that reach levels similar to those observed today in the North Pacific. While a substantial nutrient increase in the mid-depth North Atlantic cannot be ruled out during these events, changes of pore water chemistry and Cd/P fractionation during biological uptake offer alternative scenarios to explain the peak Cdw maxima. |
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