Constraints and interpretation of 87Sr/86Sr ratios in Cenozoic dolomites

Volker C. Vahrenkamp, Peter K. Swart, Joaquin Ruiz

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Replacement dolomitization by seawater has been modeled in order to quantify the Sr‐isotope signature in Cenozoic dolomites as a function of precursor mineralogy and 87Sr/86Sr ratio, reaction stoichiometry and 87Sr/86Sr ratio of the dolomitizing fluids. High Sr carbonates, such as aragonite, may introduce a significant precursor memory into an otherwise seawater dominated Sr‐isotope signature if small quantities of seawater per unit volume of precursor carbonate are involved. Dolomitization of low Sr carbonates (i.e. low‐Mg calcite) are shown to create an isotopic signature indistinguishable from that of the seawater involved in the reaction. Therefore, by comparison with the Sr‐isotope evolution curve of seawater, the‐ 87Sr/86Sr ratios of the dolomites can be used to record the oldest possible age of dolomitization and the youngest age of deposition. The implications for this approach have been applied to data obtained from a dolomitized core from Little Bahama Bank, Bahamas. Two periods of dolomitization are recognized, one in the early Late Miocene involving Middle Miocene or older rocks, and a second one around 2.4 Ma ago affecting early Pliocene carbonates.

Original languageEnglish (US)
Pages (from-to)385-388
Number of pages4
JournalGeophysical Research Letters
Volume15
Issue number4
DOIs
StatePublished - Apr 1988

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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