Identifying outliers and assessing the accuracy of amino acid racemization measurements for use in geochronology : I. Age calibration curves | Macquarie University ResearchOnline

Home

Identifying outliers and assessing the accuracy of amino acid racemization measurements for use in geochronology : I. Age calibration curves

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/110934

18 Visitors

19 Hits

0 Downloads

Title: Identifying outliers and assessing the accuracy of amino acid racemization measurements for use in geochronology : I. Age calibration curves
Related: Quaternary geochronology, Vol. 3, No. 4 (2008), p.308-327
Related: doi: 10.1016/j.quageo.2008.04.002
Publisher: Elsevier
Date: 2008
FoR/RFCD Code(s): 040200 Geochemistry 040300 Geology
Author/Creator: Kosnik, Matthew A
Author/Creator: Kaufman, Darrell S
Author/Creator: Hua, Quan
Description: Numerical ages derived from amino acid racemization (AAR) geochronology are typically based on calibration curves that relate the extent of AAR to the age of independently dated specimens. Here we compare options for developing calibration curves and quantifying age uncertainties using AAR data from 481 late Holocene shells, and AMS 14C analyses of 36 shells of four molluscan taxa (Ethalia, Natica, Tellina, and Turbo) collected from shallow sediment cores from a back-reef lagoon of the central Great Barrier Reef. The four taxa differed substantially in the quality of their geochronogical results. Explicitly including data from specimens alive at the time of collection improves calibration curves, but weighting numerical ages based on their uncertainty has no effect. Calibration curve statistics do not adequately assess calibration uncertainty. The relation between ages inferred from different amino acids is recommended for identifying aberrant specimens and quantifying the uncertainty of inferred ages. For this study, the AAR ages based on two amino acids (aspartic acid and glutamic acid) exceed 200 yr or 20% of their mean inferred age in ~ 15% of the specimens. Once these were removed, the mean age error (1Ï¿) for individual specimens based on two amino acids analyzed in duplicate subsamples ranged from 53 to 142 yr for Tellina and Turbo, respectively, or about a 30% age error for these relatively young shells. This compares favorably with analytical errors estimated at 50 yr or 5%. The presence of notable outliers undetectable using data from single amino acids emphasizes the importa nce of analyzing multiple amino acids.
Description: 20 page(s)
Subject Keyword: 040200 Geochemistry
Subject Keyword: 040300 Geology
Subject Keyword: Amino acid geochronology
Subject Keyword: mollusca
Subject Keyword: holocene
Subject Keyword: carbonate sediments
Subject Keyword: carbon-14
Subject Keyword: age calibration curves
Resource Type: journal article
Organisation: Macquarie University. Dept. of Biological Sciences

Identifier: http://hdl.handle.net/1959.14/110934
Identifier: ISSN:1871-1014
Identifier: mq-rm-2009011174
Language: eng
Reviewed

Macquarie University ResearchOnline

Search

Browse

Highlights

Resources