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The effect of species on lacustrine δ 18 O diatom and its implications for palaeoenvironmental reconstructions
Author(s) -
BAILEY HANNAH L.,
HENDERSON ANDREW C. G.,
SLOANE HILARY J.,
SNELLING ANDREA,
LENG MELANIE J.,
KAUFMAN DARRELL S.
Publication year - 2014
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2711
Subject(s) - diatom , frustule , geology , fractionation , biogenic silica , isotopes of oxygen , δ18o , equilibrium fractionation , holocene , sediment , sedimentary rock , mineralogy , stable isotope ratio , oceanography , paleontology , chemistry , isotope fractionation , geochemistry , physics , organic chemistry , quantum mechanics
ABSTRACT The oxygen isotope composition of diatom silica (δ 18 O diatom ) is increasingly being used to reconstruct climate from marine and lacustrine sedimentary archives. Although diatoms are assumed to precipitate their frustule in isotopic equilibrium with their surrounding water, it is unclear whether internal processes of a given species affect the fractionation of oxygen between the water and the diatom. We present δ 18 O diatom data from two diatom size fractions (3–38 and >38 µm) characterized by different species in a sediment core from Heart Lake, Alaska. Differences in δ 18 O diatom between the two size fractions varies from 0 to 1.2‰, with a mean offset of 0.01‰ ( n = 20). Fourier transform infrared spectroscopy confirms our samples consist of pure biogenic silica (SiO 2 ) and δ 18 O diatom trends are not driven by contamination. The maximum offset is outside the range of error, but the mean is within analytical error of the technique (± 1.06‰), demonstrating no discernible species‐dependent fractionation in δ 18 O diatom . We conclude that lacustrine δ 18 O diatom measurements offer a reliable and valuable method for reconstructing δ 18 O water . Considering the presence of small offsets in our two records, we advise interpreting shifts in δ 18 O diatom only where the magnitude of change is greater than the combined analytical error.