Correlative relationships between carbon-and oxygen-isotope records in two cool-temperate brachiopod species off otsuchi Bay, Northeastern Japan

Kazuyuki Yamamoto, Ryuji Asami, Yasufumi Iryu

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We present high-resolution, three-dimensional carbon (δ13C)-and oxygen (δO)-isotope compositions from calcite shells of two modern brachiopod species (Terebratulina crossei and Terebratalia coreanica) and their correlative relationships. δ13C and δ18O values from the secondary shell layer, which constitutes the main body of a brachiopod shell, are in and/or out of the range of δ13C and δ18O values of calcite precipitated in isotopic equilibrium with ambient seawater (equilibrium calcite). The δC and δ18O values of samples from the outermost part of the secondary shell layer show positive correlations. The values of high-growth-rate portions are less than those of low-growth-rate portions; these results are ascribed to a kinetic isotope fractionation effect. Metabolic influences are identified in the isotopic compositions of the low-growth-rate portions for T. coreanica, resulting in decreases in δ13C values compared with those of equilibrium calcite. We illustrate the effects of kinetic isotope fractionation and metabolism on the isotopic compositions of brachiopod shell calcite, which vary among shell portions within a single shell, as well as between the two species. However, appropriate selection of brachiopod taxa and shell portions that reflect the isotopic composition of ambient seawater enables their use as a reliable paleoenvironmental proxy.

Original languageEnglish
Pages (from-to)12-26
Number of pages15
JournalPaleontological Research
Volume17
Issue number1
DOIs
Publication statusPublished - 2013 Apr 1

Keywords

  • Brachiopoda
  • carbon isotope
  • isotopic equilibrium
  • kinetic effect
  • oxygen isotope
  • paleoenvironmental proxy

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Palaeontology

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