Amino acid geochronology of individual foraminifer (Pulleniatina obliquiloculata) tests, north Queensland margin, Australia

A new approach to correlating and dating Quaternary tropical marine sediment cores

Paul J. Hearty, Michael J. O'Leary, Darrell S Kaufman, Michael C. Page, Jordon Bright

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

In this study, we demonstrate the utility of amino acid geochronology based on single-foraminiferal tests in Quaternary sediment cores from the Queensland margin, Australia. The large planktonic foraminifer Pulleniatina obliquiloculata is ubiquitous in shelf, slope, and basin sediments of north Queensland as well as pantropical oceans. Fossil tests are resistant to dissolution, and retain substantial concentrations of amino acids (2-4 nmol mg-1 of shell) over hundreds of thousands of years. Amino acid D and L isomers of aspartic acid (Asp) and glutamic acid (Glu) were separated using reverse phase chromatography, which is sensitive enough to analyze individual foraminifera tests. In all, 462 Pulleniatina tests from 80 horizons in 11 cores exhibit a systematic increase in D/L ratios down core. D/L ratios were determined in 32 samples whose ages are known from AMS 14C analyses. In all cases, the Asp and Glu D/L ratios are concordant with 14C age. D/L ratios of equal-age samples are slightly lower for cores taken from deeper water sites, reflecting the sensitivity of the rate of racemization to bottom water temperature. Beyond the range of 14C dating, previously identified marine oxygen-isotope stage boundaries provide approximate ages of the sediments up to about 500,000 years. For this longer time frame, D/L ratios also vary systematically with isotope-correlated ages. The rate of racemization for Glu and Asp was modeled using power functions. These equations can be used to estimate ages of samples from the Queensland margin extending back at least 500,000 years. This analytical approach provides new opportunities for geochronological control necessary to understand fundamental sedimentary processes affecting a wide range of marine environments.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalPaleoceanography
Volume19
Issue number4
DOIs
StatePublished - Dec 2004

Fingerprint

geochronology
foraminifera
marine sediment
sediment core
amino acid
aspartic acid
racemization
acid
accelerator mass spectrometry
planktonic foraminifera
bottom water
sediment
chromatography
oxygen isotope
test
dating
marine environment
water temperature
deep water
dissolution

Keywords

  • Amino acid racemization
  • Foraminifera
  • Geochronology
  • Marine sediment
  • Quaternary stratigraphy
  • Queensland margin

ASJC Scopus subject areas

  • Oceanography
  • Palaeontology

Cite this

Amino acid geochronology of individual foraminifer (Pulleniatina obliquiloculata) tests, north Queensland margin, Australia : A new approach to correlating and dating Quaternary tropical marine sediment cores. / Hearty, Paul J.; O'Leary, Michael J.; Kaufman, Darrell S; Page, Michael C.; Bright, Jordon.

In: Paleoceanography, Vol. 19, No. 4, 12.2004, p. 1-14.

Research output: Contribution to journalArticle

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