Testing the impact of diagenesis on the δ18O and δ13C of benthic foraminiferal calcite from a sediment burial depth transect in the Equatorial Pacific

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doi: 10.1002/palo.20045
Author(s): Edgar, Kirsty M.; Palike, Heiko; Wilson, Paul A.
Author Affiliation(s): Primary:
Cardiff University, School of Earth and Ocean Sciences, Cardiff, United Kingdom
Other:
University of Bremen, Germany
University of Southampton, United Kingdom
Volume Title: Paleoceanography
Source: Paleoceanography, 28(3), p.468-480. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 65 refs.; illus., incl. 1 table, sketch map
Summary: Stable oxygen and carbon isotope (δ18O and δ13C) 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 δ18O and δ13C 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 δ18O and δ13C 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. Abstract Copyright (2013), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 10 Paleontology, Invertebrate; Anomalinidae; Benthic taxa; Burial; C-13/C-12; Calcite; Carbon; Carbonates; Cassidulinacea; Cenozoic; Cibicidoides; Cibicidoides grimsdalei; Diagenesis; East Pacific; Equatorial Pacific; Expedition 320; Expeditions 320/321; Foraminifera; IODP Site U1331; IODP Site U1332; IODP Site U1333; IODP Site U1334; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 199; Microfossils; Morphology; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 1218; ODP Site 1219; Ocean Drilling Program; Oligocene; Oxygen; Pacific Ocean; Paleogene; Protista; Recrystallization; Rotaliina; SEM data; Stable isotopes; Taphonomy; Tertiary; Tests
Coordinates: N051844 N120405 W1261700 W1420942
N074800 N074800 W1420100 W1420100
N085300 N085300 W1352200 W1352200
Record ID: 2014041129
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom