Isotope offsets in marine diatom δ18O over the last 200 ka

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doi: 10.1002/jqs.1185
Author(s): Swann, George E. A.; Leng, Melanie J.; Sloane, Hilary J.; Maslin, Mark A.
Author Affiliation(s): Primary:
British Geological Survey, National Environment Reserch Council Isotope Geosciences Laboratory, Keyworth, United Kingdom
Swansea University, United Kingdom
Lancaster University, United Kingdom
University College London, United Kingdom
Volume Title: Isotopes in biogenic silica (IBiS)
Volume Author(s): Leng, Melanie J., editor; Street-Perrott, F. Alayne; Barker, Philip A.
Source: JQS. Journal of Quaternary Science, 23(4), p.389-400; Third meeting on ISOtopes in PALaeoenvironmental reconstruction (ISOPAL), Nottingham, United Kingdom, April 18, 2007, edited by Melanie J. Leng, F. Alayne Street-Perrott and Philip A. Barker. Publisher: John Wiley and Sons for the Quaternary Research Association, Chichester, United Kingdom. ISSN: 0267-8179
Note: In English. 64 refs.; illus., incl. 3 tables, sketch map
Summary: Previous work has suggested that a species effect may be present in diatom oxygen isotope ratios (δ18Odiatom). While predominantly attributed to be a size-related species effect, currently the precise mechanism remains unknown. Here, two size fractions of diatoms (38-75 µm and >100 µm) covering the last 200 ka are analyzed for δ18O from ODP Site 882 in the North-West Pacific Ocean. Synchronous variations of up to 13 per mil occur in both size fractions. However, large isotope offsets (mean = 2.02 per mil) exist between the two fractions with no relationship between their magnitude and the overlying paleoenvironmental conditions. In contrast to earlier work from the same site, no one size fraction is constantly higher or lower in δ18O relative to the other. As such, the dominant mechanism is most likely separate to the size effect previously detected. In addition, no relationship exists between the magnitude of the offsets and the species composition of the two size fractions. The presence of these isotope offsets imposes significant constraints upon the future use of δ18Odiatom in paleoceanographic reconstructions and reiterates the need to extract and analyze only species- and size-specific diatom samples.
Year of Publication: 2008
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Algae; Biogenic processes; Cenozoic; Diatoms; Framework silicates; Holocene; Isotope ratios; Isotopes; Leg 145; Marine environment; Microfossils; North Pacific; Northwest Pacific; O-18/O-16; ODP Site 882; Ocean Drilling Program; Opal; Oxygen; Pacific Ocean; Paleoenvironment; Plantae; Pleistocene; Quaternary; Silica; Silica minerals; Silicates; Stable isotopes; Upper Pleistocene; West Pacific
Coordinates: N502148 N502148 E1673600 E1673600
Record ID: 2008102359
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom