Southeastern Atlantic deep-water evolution during the late-middle Eocene to earliest Oligocene (Ocean Drilling Program Site 1263 and Deep Sea Drilling Project Site 366)

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doi: 10.1130/GES01268.1
Author(s): Langton, Samantha J.; Rabideaux, Nathan M.; Borrelli, Chiara; Katz, Miriam E.
Author Affiliation(s): Primary:
Rensselaer Polytechnic Institute, Department of Earth and Environmental Sciences, Troy, NY, United States
University of Rochester, United States
Volume Title: Geosphere (Boulder, CO)
Source: Geosphere (Boulder, CO), 12(3), p.1032-1047. Publisher: Geological Society of America, Boulder, CO, United States. ISSN: 1553-040X
Note: In English. 111 refs.; illus., incl. 3 tables, sketch map
Summary: Comparison of new benthic foraminiferal δ18O and δ13C records from Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic, 2100 m paleodepth) and Deep Sea Drilling Project (DSDP) Site 366 (Sierra Leone Rise, eastern equatorial Atlantic, 2200-2800 m paleodepth) with published data from Atlantic and Southern Ocean sites provides the means to reconstruct the development of deep-water circulation in the southeastern Atlantic from the late-middle Eocene to the earliest Oligocene. Our comparison shows that in the late-middle Eocene (ca. 40 Ma), the South Atlantic was characterized by a homogeneous thermal structure. Thermal differentiation began ca. 38 Ma. By 37.6 Ma, Site 1263 was dominated by Southern Component Water; at the same time, warm saline deep water filled the deeper South Atlantic (recorded at southwest Atlantic ODP Site 699, paleodepth 3400 m, and southeast Atlantic ODP Site 1090, paleodepth 3200 m). The deep-water source to eastern equatorial Site 366 transitioned to Northern Component Water ca. 35.6-35 Ma. Progressive cooling at Site 1263 during the middle to late Eocene and deep-water thermal stratification in the South Atlantic may be attributed at least in part to the gradual deepening and strengthening of the proto-Antarctic Circumpolar Current from the late-middle Eocene to the earliest Oligocene, as the Drake and Tasman gateways opened. Our isotopic comparisons across depth and latitude provide evidence of the development of deep-water circulation similar to modern-day Atlantic Meridional Overturning Circulation.
Year of Publication: 2016
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Biostratigraphy; C-13/C-12; Carbon; Cenozoic; Chemostratigraphy; Cores; DSDP Site 366; Deep Sea Drilling Project; Eocene; Equatorial Atlantic; Foraminifera; Invertebrata; Isotope ratios; Isotopes; Leg 208; Leg 41; Lithofacies; Lower Oligocene; Marine environment; Microfossils; North Atlantic; O-18/O-16; ODP Site 1263; Ocean Drilling Program; Ocean circulation; Oligocene; Oxygen; Paleo-oceanography; Paleoenvironment; Paleogene; Protista; Reconstruction; Sierra Leone Rise; South Atlantic; Stable isotopes; Stratification; Tertiary; Walvis Ridge
Coordinates: S283200 S283200 E0024700 E0024700
N054040 N054041 W0195104 W0195105
Record ID: 2016076737
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