A Pre-treatment Routine for Correcting Age-Offsets on AMS Radiocarbon Dated Ceramic Residue

校正 AMS 放射性碳测年陶瓷残渣年龄偏移的预处理程序

• 批准号: 1530274
• 负责人: Donna Roper
• 金额: $ 19.12万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1530274&HistoricalAwards=false
• 关键词: Pre; treatment; Routine; Correcting; Age

Dr. Donna C. Roper, from Kansas State University, and Dr. Linda Scott Cummings, from PaleoResearch Institute, will collaborate on a study designed to develop a pre-treatment protocol for correcting age-offsets on AMS radiocarbon dated ceramic residue. Since its introduction in the mid-twentieth century, radiocarbon dating has been vital to archaeologists as well as biologists, geologists and scientists conducting basic and applied research in other fields. The method has seen considerable advancement in the ensuing decades, enabling development of evermore accurate and precise timelines. Capable of producing high precision dates, the AMS technique permits assay of small materials, such as individual corn kernel fragments or seeds that are short-lived and contemporaneous with their context, thus yielding ages with higher accuracy than ever before. Also, the range of organic materials believed to be appropriate for archaeological dating is broadened. Charred food burned onto ceramic vessels during cooking, often termed ceramic residue, is one of the materials now commonly selected for dating and increasingly used in North America, Europe, and Asia. As its use increases, ceramic residue ages are often noted to be older than dates on other short-lived material from the same context, and thus are not accurate. Continuing to assume the accuracy of these dates and integrating them into timelines degrades chronologies precisely at the time the discipline is able to produce timelines of moderately high resolution and enable archaeologists to work toward viable narratives of historical process.Two previous approaches to addressing the problem have included determining chemical composition as a predictor of which samples likely are affected, and developing correction factors for ages. Neither is proving capable of satisfactorily addressing the problem; indeed, recent conclusions regarding correction factors are that age offsets are too variable for any single local, or regional correction factor to be accurate. The study team for this project proposes a third approach that includes a pre-treatment protocol to remove and discard compounds responsible for the anomalous dates. As a result, dates may be obtained on a fraction of residue shown to produce dates contemporaneous with associated short-lived materials. Limited trials have produced encouraging results toward developing a ceramic residue treatment protocol for general use. AMS dates on residue and on context materials known to produce accurate ages will be paired to test the efficacy of the developing method. Tests will consist of dating multiple fractions, including removed compounds, from a few residues to obtain information concerning the old carbon content. Samples will be drawn from late prehistoric individual dwellings in the North American Great Plains that had use-lives on the order of a decade to a decade-and-a-half. Testing and vetting methods aims toward development of a pre-treatment protocol capable of obtaining accurate dates on ceramic residue anywhere in the world, as residues are fast becoming a significant part of the radiocarbon dating record. Furthermore, this method will lead to a future effort involving chemical separation of compounds containing old carbon in or adhering to other materials, opening the door to application of this protocol to additional samples so they may produce accurate and concordant radiocarbon dates.

堪萨斯州立大学的Donna C. Roper博士和Paleoresearch Institute的Linda Scott Cummings博士将合作进行一项研究，旨在制定预处理方案，以纠正AMS Radiocarbon Edocared Ceramic残留物上的年龄。自20世纪中叶引入以来，放射性碳的约会对考古学家以及生物学家，地质学家和科学家在其他领域进行基础和应用研究至关重要。该方法在随后的几十年中取得了长足的进步，从而发展了更准确，更精确的时间表。 AMS技术能够产生高精度的日期，允许对小型材料进行测定，例如单个玉米粒碎片或与众不同的种子，它们是短暂且同时存在的种子，因此比以往任何时候都以更高的精度产生了年龄。同样，宽广的有机材料范围也扩大了考古标准。 在烹饪过程中燃烧在陶瓷容器上的烧焦食品通常被称为陶瓷残留物，是现在通常被选择用于约会并越来越多地使用的材料之一。 随着其使用的增加，陶瓷残基年龄通常被认为比其他短暂材料的日期年龄在同一背景下的日期，因此不准确。继续假设这些日期的准确性并将它们整合到时间表中，在学科能够产生适度高分辨率的时间表时，会降低时间表，并使考古学家能够朝着历史过程的可行叙述努力。以前的方法解决了该问题的先前方法，包括确定化学构成作为对型号的预测，并且可以预测型号，并且不断发展。没有证明能够令人满意地解决这个问题。实际上，关于校正因素的最新结论是，年龄偏移太可变了，以至于任何单个局部或区域校正因子都无法准确。 该项目的研究团队提出了一种第三种方法，其中包括一种预处理方案，以删除和丢弃负责异常日期的化合物。结果，可以在一小部分残留物上获得日期，这些残留物与相关的短寿命材料同时产生日期。有限的试验产生了令人鼓舞的结果，以制定陶瓷残留治疗方案供一般使用。 AMS关于残基和已知产生准确年龄的上下文材料的日期将配对以测试开发方法的功效。测试将包括从几个残基中的多个分数（包括去除的化合物）约会，以获取有关旧碳含量的信息。样本将从北美大平原的晚期史前个人住所中获取，这些史遍历十年到十年半的时间。测试和审查方法旨在制定能够在世界任何地方获得陶瓷残基上准确日期的预处理方案，因为残基迅速成为放射性碳年代日期记录的重要组成部分。此外，这种方法将导致未来的努力，涉及将含有旧碳或粘附在其他材料的化合物的化学分离，打开该方案将其应用于其他样品的大门，以便它们可能产生准确且一致的放射性碳日期。