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Testing the impact of diagenesis on the ?18O and ?13C of benthic foraminiferal calcite from a sediment burial depth transect in the equatorial Pacific

Testing the impact of diagenesis on the ?18O and ?13C of benthic foraminiferal calcite from a sediment burial depth transect in the equatorial Pacific
Testing the impact of diagenesis on the ?18O and ?13C of benthic foraminiferal calcite from a sediment burial depth transect in the equatorial Pacific
Stable oxygen and carbon isotope (?18O and ?13C) values measured in foraminiferal calcite are one of the primary tools used in paleoceanography. Diagenetic recrystallization of foraminiferal calcite can act to reset primary isotopic values, but its effects are typically poorly quantified. Here we test the impact of early stage diagenesis on stable isotope records generated from a suite of drill sites in the equatorial Pacific Ocean recovered during Ocean Drilling Program Leg 199 and Integrated Ocean Drilling Program Expedition 320. Our selected sites form paleowater and burial depth transects, with excellent stratigraphic control allowing us to confidently correlate our records. We observe large intersite differences in the preservation state of benthic foraminiferal calcite, implying very different recrystallization histories, but negligible intersite offsets in benthic ?18O and ?13C values. We infer that diagenetic alteration of benthic foraminiferal calcite (in sedimentary oozes) must predominantly occur at shallow burial depths (<100?m) where offsets in both the temperature and isotopic composition of waters in which the foraminifera calcified and pore waters in which diagenesis occurs are small. Our results suggest that even extensive recrystallization of benthic foraminiferal calcite results in minimal shifts from primary ?18O and ?13C values. This finding supports the long-held suspicion that diagenetic alteration of foraminiferal calcite is less problematic in benthic than in planktic foraminifera and that in deep-sea sediments routinely employed for paleoceanographic studies benthic foraminifera are robust recorders of stable isotope values in the fossil record.
oligocene, benthic foraminifera, diagenesis, recrystallisation, stable isotopes, Integrated Ocean Drilling Program
0883-8305
468-480
Edgar, Kirsty M.
c180d215-e9ee-4a79-8274-a1e8a300c07c
Pälike, Heiko
41eaa71b-043f-4e6d-87b3-ac5e6ea239c5
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Edgar, Kirsty M.
c180d215-e9ee-4a79-8274-a1e8a300c07c
Pälike, Heiko
41eaa71b-043f-4e6d-87b3-ac5e6ea239c5
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6

Edgar, Kirsty M., Pälike, Heiko and Wilson, Paul A. (2013) Testing the impact of diagenesis on the ?18O and ?13C of benthic foraminiferal calcite from a sediment burial depth transect in the equatorial Pacific. Paleoceanography, 28 (3), 468-480. (doi:10.1002/palo.20045).

Record type: Article

Abstract

Stable oxygen and carbon isotope (?18O and ?13C) values measured in foraminiferal calcite are one of the primary tools used in paleoceanography. Diagenetic recrystallization of foraminiferal calcite can act to reset primary isotopic values, but its effects are typically poorly quantified. Here we test the impact of early stage diagenesis on stable isotope records generated from a suite of drill sites in the equatorial Pacific Ocean recovered during Ocean Drilling Program Leg 199 and Integrated Ocean Drilling Program Expedition 320. Our selected sites form paleowater and burial depth transects, with excellent stratigraphic control allowing us to confidently correlate our records. We observe large intersite differences in the preservation state of benthic foraminiferal calcite, implying very different recrystallization histories, but negligible intersite offsets in benthic ?18O and ?13C values. We infer that diagenetic alteration of benthic foraminiferal calcite (in sedimentary oozes) must predominantly occur at shallow burial depths (<100?m) where offsets in both the temperature and isotopic composition of waters in which the foraminifera calcified and pore waters in which diagenesis occurs are small. Our results suggest that even extensive recrystallization of benthic foraminiferal calcite results in minimal shifts from primary ?18O and ?13C values. This finding supports the long-held suspicion that diagenetic alteration of foraminiferal calcite is less problematic in benthic than in planktic foraminifera and that in deep-sea sediments routinely employed for paleoceanographic studies benthic foraminifera are robust recorders of stable isotope values in the fossil record.

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More information

Published date: September 2013
Keywords: oligocene, benthic foraminifera, diagenesis, recrystallisation, stable isotopes, Integrated Ocean Drilling Program
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 359626
URI: https://eprints.soton.ac.uk/id/eprint/359626
ISSN: 0883-8305
PURE UUID: 61153d20-b1d3-4ecd-9697-a88cfd96e945

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Date deposited: 06 Nov 2013 14:55
Last modified: 16 Jul 2019 21:17

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Contributors

Author: Kirsty M. Edgar
Author: Heiko Pälike
Author: Paul A. Wilson

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