Refining Background Corrections for Radiocarbon Dating of Bone Collagen at Orau
Refining Background Corrections for Radiocarbon Dating of Bone Collagen at Orau
复制标题
奥劳骨胶原放射性碳测年的精炼背景校正
DOI：
10.1017/s003382220004563x
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发表时间：
2010
期刊：
影响因子：
8.3
通讯作者：
T. Higham
中科院分区：
文献类型：
--
作者：
R. E. Wood;C. B. Ramsey;T. Higham
在放射性碳测年样品的实验室预处理过程中，可能会向样品中加入少量的碳。污染物可以在任何阶段加入：化学预处理、燃烧成CO2、石墨化或加速器质谱（AMS）测量期间。这种碳污染通常是现代的，因此对距今超过1.25万年的样品会产生特别严重的影响。在牛津放射性碳加速器单元（ORAU）使用超滤方案从骨中提取胶原蛋白的过程中，向样品中加入少量的新碳。目前，当从骨中提取少于10 mg的胶原蛋白时，这种污染的特征很差。最近，随着人们对直接测定尼安德特人遗骸和旧石器时代晚期骨制品的年龄越来越感兴趣，对14C浓度接近AMS测量检测限的小胶原样品的需求有所增加。本文旨在通过重新检查骨的燃烧背景和随后的预处理背景，将产生可靠数据所需的最小胶原样本量从10 mg减少到5 mg。直接燃烧尼龙的136次测量的平均值表明，每个样品中添加了0.0007 ± 0.001 mg的现代碳，尽管分布是正偏态的。对从背景年龄骨中提取的52个胶原蛋白样本的测量结果进行回归分析，得出在ORAU治疗的骨的背景值略低于50，000 BP。
During the laboratory pretreatment of samples for radiocarbon dating, small amounts of carbon may be added to a sample. Contamination can be incorporated at any stage: during chemical pretreatment, combustion to CO2, graphitization, or accelerator mass spectrometry (AMS) measurement. Such carbon contamination is often modern in age, and so can have an especially severe effect on samples older than ∼25 ka BP. During the extraction of collagen from bone using the ultrafiltration protocol at the Oxford Radiocarbon Accelerator Unit (ORAU), small amounts of young carbon are added to the sample. Currently, this contamination is poorly characterized when less than 10 mg of collagen is extracted from a bone. Demand to date small collagen samples with 14C concentrations that approach the detection limit of AMS measurement has increased recently with the growing interest in, for example, directly dating Neanderthal remains and Upper Paleolithic bone artifacts. This paper aims to reduce the minimum collagen sample size required to produce a reliable date from 10 to 5 mg by re-examining the combustion background and subsequently the pretreatment background for bone. The average of 136 measurements of directly combusted nylon suggests that 0.0007 ± 0.001 mg of modern carbon is added to each sample, although the distribution is positively skewed. Regression analysis of the measurements of 52 collagen samples extracted from a bone of background age results in a background of just less than 50,000 BP for bone treated at ORAU.