Geochemical signatures in Late Triassic brachiopods from New Caledonia

C. V. Ullmann*, H. J. Campbell, R. Frei, C. Korte

*Corresponding author for this work
8 Citations (Scopus)

Abstract

Brachiopod fossils from the sedimentary sequences of the Téremba Terrane (New Caledonia) provide a unique opportunity to study the environmental parameters of the Late Triassic. 87Sr/86Sr ratios, δ13C and δ18O values, and Sr/Ca, Mg/Ca and Mn/Ca ratios were measured on brachiopods from Oretian to Otapirian (Norian to Rhaetian) fossil localities of the Baie de St.-Vincent area. Post-depositional impacts on the geochemical proxies were investigated by analysing calcite cements and partly recrystallized shell material. Diagenetic fluids carried strontium with a low 87Sr/86Sr ratio of c. 0.7065, and light δ13C values of c.-20‰, suggesting major contributions by oxidized organic matter. Diagenetic equilibrium was reached at δ18O values of c.-12‰, very low Sr/Ca ratios of < 0.05 mmol/mol and locally variable Mn/Ca ratios of up to 5.9 mmol/mol. Results from the best-preserved samples suggest that calcification temperatures of Warepan and Otapirian brachiopods from New Caledonia were consistently ≥ 15 °C.

Original languageEnglish
JournalNew Zealand Journal of Geology and Geophysics
Volume57
Issue number4
Pages (from-to)420-431
Number of pages12
ISSN0028-8306
DOIs
Publication statusPublished - Oct 2014

Keywords

  • Sr/Sr
  • Brachiopod
  • Diagenesis
  • New Caledonia
  • Stable isotopes
  • Trace elements

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