Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

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doi: 10.1002/2017PA003135
Author(s): Huck, Claire E.; Flierdt, Tina; Bohaty, Steven M.; Hammond, Samantha J.
Author Affiliation(s): Primary:
Imperial College London, Department of Earth Science and Engineering, London, United Kingdom
University of Southampton, United Kingdom
Open University, United Kingdom
Volume Title: Paleoceanography
Source: Paleoceanography, 32(7), p.674-691. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 141 refs.; illus., incl. 1 table, sketch maps
Summary: We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (<500 m) to intermediate/deep (∼1000-2500 m) paleowater depths. Unradiogenic seawater Nd isotopic compositions, reconstructed from fish teeth at intermediate/deep Indian Ocean pelagic sites (Ocean Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant Southern Ocean-sourced contribution to regional deep waters (εNd(t) = -9.3 ± 1.5). IODP Site U1356 off the coast of Adelie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (εNd(t) = -8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by ∼2 εNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene. Abstract Copyright (2017), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2017
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Campbell Plateau; Cenozoic; Climate change; DSDP Site 264; DSDP Site 277; Deep Sea Drilling Project; Eocene; Expedition 318; IODP Site U1356; Indian Ocean; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Kerguelen Plateau; Leg 119; Leg 121; Leg 189; Leg 28; Leg 29; Marine environment; Marine sediments; Metals; Naturaliste Plateau; Nd-144/Nd-143; Neodymium; Ninetyeast Ridge; ODP Site 1171; ODP Site 738; ODP Site 757; Ocean Drilling Program; Ocean circulation; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Paleogene; Pelagic environment; Rare earths; Sediments; Shelf environment; South Pacific; Southern Ocean; Southwest Pacific; Stable isotopes; Tasman Sea; Teeth; Tertiary; West Pacific
Coordinates: S624233 S624232 E0824715 E0824714
S170128 S170123 E0881054 E0881048
S345808 S345808 E1120241 E1120241
S521326 S521325 E1661129 E1661128
Record ID: 2017085895
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom