Identifying outliers and assessing the accuracy of amino acid racemization measurements for geochronology: II. Data screening

Kosnik, Matthew A., and Kaufman, Darrell S. (2008) Identifying outliers and assessing the accuracy of amino acid racemization measurements for geochronology: II. Data screening. Quaternary Geochronology, 3 (4). pp. 328-341.

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Abstract

Amino acid racemization (AAR) is a cost-effective method for dating the large numbers of specimens required for time-averaging studies. Because the aim of time-averaging studies is to determine the structure of the age distribution, any data screening must be done cautiously and systematically. Methods to quantitatively assess the quality of AAR data and to identify aberrant specimens are under-developed. Here we examine a variety of screening criteria for identifying outliers and determining the suitability of specimens for numerical dating including: high serine concentrations (modern contamination), covariance of aspartic acid (Asp) and glutamic acid (Glu) concentrations (diagenetic influences), replication of measurements (specimen heterogeneity), and the relation between Asp and Glu d/l values (internal consistency). This study is based on AAR analyses of 481 late Holocene shells of four molluscan taxa (Ethalia, Natica, Tellina, and Turbo) collected from shallow sediment cores from the central Great Barrier Reef. Different outliers are flagged by the different screening criteria, and 6% of specimens were found to be unsuitable for time-averaging analyses based on screening the raw AAR data. We recommend a hybrid approach for identifying outliers and specimens for numerical dating.

Item ID: 19403
Item Type: Article (Refereed Research - C1)
Keywords: mollusca; amino acid geochronology; holocene; carbonate sediments; time-averaging; Great Barrier Reef; amino acid racemization
ISSN: 1871-1014
Date Deposited: 20 Jan 2012 02:51
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 50%
04 EARTH SCIENCES > 0403 Geology > 040308 Palaeontology (incl Palynology) @ 50%
SEO Codes: 96 ENVIRONMENT > 9699 Other Environment > 969999 Environment not elsewhere classified @ 33%
96 ENVIRONMENT > 9699 Other Environment > 969902 Marine Oceanic Processes (excl. Climate Related) @ 34%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 33%
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