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Global change across the Oligocene-Miocene Transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

Global change across the Oligocene-Miocene Transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)
Global change across the Oligocene-Miocene Transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)
The Oligocene-Miocene transition (OMT) (~23?Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23?Myr long high-resolution (~3?kyr) benthic foraminiferal oxygen and carbon isotope (?18O and ?13C) record from Integrated Ocean Drilling Program Site U1334 (eastern equatorial Pacific Ocean), covering the interval from 21.91 to 24.14?Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a ~1‰ increase in benthic foraminiferal ?18O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the equatorial Atlantic and the equatorial Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the ?18O values between infaunal and epifaunal species occurs between 22.8 and 23.2?Ma, associated with the maximum ?18O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of ~50?m across the OMT.
stable isotopes, Oligocene-Miocene transition, benthic foraminfera
0883-8305
81-97
Beddow, Helen M.
7d12eaf5-0759-4ec6-b051-f0e23699a2d0
Liebrand, Diederik
bef7cbd7-4fa7-453c-9961-c950a5b87795
Sluijs, Appy
af623507-b795-4458-8ca5-cce783869a3d
Wade, Bridget S.
882ef710-e0e7-46a1-b382-eb48b1b31a03
Lourens, Lucas J.
d3c5b95b-b14d-4f5f-8ec1-f3f517335ca1
Beddow, Helen M.
7d12eaf5-0759-4ec6-b051-f0e23699a2d0
Liebrand, Diederik
bef7cbd7-4fa7-453c-9961-c950a5b87795
Sluijs, Appy
af623507-b795-4458-8ca5-cce783869a3d
Wade, Bridget S.
882ef710-e0e7-46a1-b382-eb48b1b31a03
Lourens, Lucas J.
d3c5b95b-b14d-4f5f-8ec1-f3f517335ca1

Beddow, Helen M., Liebrand, Diederik, Sluijs, Appy, Wade, Bridget S. and Lourens, Lucas J. (2016) Global change across the Oligocene-Miocene Transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean). Paleoceanography, 31 (1), 81-97. (doi:10.1002/2015PA002820).

Record type: Article

Abstract

The Oligocene-Miocene transition (OMT) (~23?Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23?Myr long high-resolution (~3?kyr) benthic foraminiferal oxygen and carbon isotope (?18O and ?13C) record from Integrated Ocean Drilling Program Site U1334 (eastern equatorial Pacific Ocean), covering the interval from 21.91 to 24.14?Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a ~1‰ increase in benthic foraminiferal ?18O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the equatorial Atlantic and the equatorial Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the ?18O values between infaunal and epifaunal species occurs between 22.8 and 23.2?Ma, associated with the maximum ?18O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of ~50?m across the OMT.

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e-pub ahead of print date: 16 January 2016
Published date: January 2016
Keywords: stable isotopes, Oligocene-Miocene transition, benthic foraminfera
Organisations: Paleooceanography & Palaeoclimate

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Local EPrints ID: 386029
URI: https://eprints.soton.ac.uk/id/eprint/386029
ISSN: 0883-8305
PURE UUID: 561cde73-de64-4b6b-87fd-a6af538f82f7

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Date deposited: 18 Jan 2016 10:28
Last modified: 09 Jan 2018 18:15

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Contributors

Author: Helen M. Beddow
Author: Diederik Liebrand
Author: Appy Sluijs
Author: Bridget S. Wade
Author: Lucas J. Lourens

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