Hearty, Paul J. and O'Leary, Michael J. and Kaufman, Darrell S. and Page, Michael C. and Bright, Jordan (2004) 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. Paleoceanography, PA4022. 1/21/2015 23:46:59. ISSN 1944-9186
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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 C-14 analyses. In all cases, the Asp and Glu D/L ratios are concordant with C-14 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 C-14 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.
| Item Type: | Article |
|---|---|
| Publisher’s Statement: | Copyright 2004 by the American Geophysical Union. |
| ID number or DOI: | 10.1029/2004PA001059 |
| Keywords: | Queensland margin; marine sediment; amino acid racemization; geochronology; foraminifera; Quaternary stratigraphy |
| Subjects: | G Geography. Anthropology. Recreation > GE Environmental Sciences |
| NAU Depositing Author Academic Status: | Faculty/Staff |
| Department/Unit: | College of Engineering, Forestry, and Natural Science > School of Earth Sciences and Environmental Sustainability |
| Date Deposited: | 04 Feb 2016 22:27 |
| URI: | http://openknowledge.nau.edu/id/eprint/1801 |
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