Southern Ocean AMOC variability recorded by neodymium isotopes from 0-1.6 Ma

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Author(s): Knudson, Karla P.; Goldstein, Steven L.; Pena, Leopoldo D.; Kim, Joohee; Seguí, Maria Jaume; Yehudai, Maayan
Author Affiliation(s): Primary:
Lamont-Doherty Earth Observatory, Palisades, NY, United States
Columbia University, United States
Universitat de Barcelona, Spain
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: North Atlantic Deep Water (NADW) represents a major water mass that drives the Atlantic Meridional Overturning Circulation (AMOC) and undergoes substantial reorganization with climate changes on millennial to orbital timescales. Here, we present new paleo-circulation records of Nd isotopes measured on fish debris and Fe-Mn encrusted foraminifera from ODP Site 1090 (42° 54.82'S, 8°53.98'E, 3702 m) from 0 to 1.6 Ma, in the context of a transect of other Nd isotope records from sites throughout the Atlantic basin (ODP Sites 607, 926, 1267, 1264, and 1088). Site 1090 is located in the Cape Basin, southeast Atlantic, near the lower boundary between NADW and Circumpolar Deep Water (CDW) and thus represents an ideal location to monitor changes in the export of NADW to the Southern Ocean, as suggested by Pena and Goldstein (2014). Our new results show that compared to other transect sites, Site 1090 (the southernmost site) records a high proportion of southern-sourced CDW relative to NADW, confirming that records from this site may be relied upon to constrain the export of NADW to the Southern Ocean through time. NADW influence was enhanced relative to CDW during interglacial climates and diminished during glacial climates, a pattern that is consistently observed throughout the basin. Fundamental circulation shifts occurred before, during, and after the Mid-Pleistocene Transition (MPT; ∼1200-700 ka), when dominant climate cycles shifted from 40 kyr to 100 kyr periodicity: before the MPT, the glacial-interglacial amplitude of NADW/CDW component fluctuations was relatively small; during the MPT, there is widespread evidence for an NADW "crisis" (as shown by Pena and Goldstein, 2014); NADW/CDW component fluctuations increased after the MPT. Overall, these results provide key insights into the close relationship between changes in global climate and AMOC behavior.
Year of Publication: 2018
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Atlantic Ocean; Ceara Rise; DSDP Site 607; Deep Sea Drilling Project; Equatorial Atlantic; IPOD; Leg 154; Leg 177; Leg 208; Leg 94; Mid-Atlantic Ridge; North Atlantic; North Atlantic Deep Water; Northeast Atlantic; ODP Site 1088; ODP Site 1090; ODP Site 1264; ODP Site 1267; ODP Site 926; Ocean Drilling Program; Ocean circulation; South Atlantic; Southern Ocean; Walvis Ridge
Coordinates: S425449 S425449 E0085359 E0085359
N034309 N034309 W0425430 W0425430
S280600 S280600 E0014300 E0014200
Record ID: 2019050044
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