Equatorial Pacific productivity changes near the Eocene-Oligocene boundary

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doi: 10.1002/2014PA002656
Author(s): Moore, T. C., Jr.; Wade, Bridget S.; Westerhold, Thomas; Erhardt, Andrea M.; Coxall, Helen K.; Baldauf, Jack; Wagner, Meghan
Author Affiliation(s): Primary:
University of Michigan, Department of Earth and Environmental Sciences, Ann Arbor, MI, United States
Other:
University College London, United Kingdom
University of Bremen, Germany
University of Cambridge, United Kingdom
Stockholm University, Sweden
Texas A&M University, United States
Central Michigan University, United States
Volume Title: Paleoceanography
Source: Paleoceanography, 29(9), p.825-844. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. NSF Grant EAR-0847300. 127 refs.; illus., incl. geol. sketch map
Summary: There is general agreement that productivity in high latitudes increased in the late Eocene and remained high in the early Oligocene. Evidence for both increased and decreased productivity across the Eocene-Oligocene transition (EOT) in the tropics has been presented, usually based on only one paleoproductivity proxy and often in sites with incomplete recovery of the EOT itself. A complete record of the Eocene-Oligocene transition was obtained at three drill sites in the eastern equatorial Pacific Ocean (ODP Site 1218 and IODP Sites U1333 and U1334). Four paleoproductivity proxies that have been examined at these sites, together with carbon and oxygen isotope measurements on early Oligocene planktonic foraminifera, give evidence of ecologic and oceanographic change across this climatically important boundary. Export productivity dropped sharply in the basal Oligocene (∼33.7 Ma) and only recovered several hundred thousand years later; however, overall paleoproductivity in the early Oligocene never reached the average levels found in the late Eocene and in more modern times. Changes in the isotopic gradients between deep- and shallow-living planktonic foraminifera suggest a gradual shoaling of the thermocline through the early Oligocene that, on average, affected accumulation rates of barite, benthic foraminifera, and opal, as well as diatom abundance near 33.5 Ma. An interval with abundant large diatoms beginning at 33.3 Ma suggests an intermediate thermocline depth, which was followed by further shoaling, a dominance of smaller diatoms, and an increase in average primary productivity as estimated from accumulation rates of benthic foraminifera. Abstract Copyright (2014), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Assemblages; Barite; C-13/C-12; Carbon; Cenozoic; Diatoms; East Pacific; Eocene; Equatorial Pacific; Expedition 320; Expeditions 320/321; Foraminifera; Framework silicates; IODP Site U1333; IODP Site U1334; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 199; Lower Oligocene; Marine environment; Microfossils; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 1218; Ocean Drilling Program; Oligocene; Opal; Oxygen; Pacific Ocean; Paleoecology; Paleoenvironment; Paleogene; Planktonic taxa; Plantae; Productivity; Protista; Radiolaria; Silica minerals; Silicates; Stable isotopes; Stratigraphic boundary; Sulfates; Tertiary; Upper Eocene
Coordinates: N085300 N085300 W1352200 W1352200
N103100 N103100 W1382510 W1382510
N080000 N080000 W1315824 W1315824
Record ID: 2014089599
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom