ESR Dating at Archaeological Sites in Europe, Africa and Asia

欧洲、非洲和亚洲考古遗址的 ESR 测年

• 批准号: 9904376
• 负责人: Bonnie Blackwell
• 金额: $ 21.41万
• 依托单位: Williams College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904376&HistoricalAwards=false
• 关键词: ESR; Dating; Archaeological; Sites; Europe

Drs. Bonnie Blackwell and Anne Skinner will conduct a series of laboratory experiments to improve the electron spin resonance (ESR) technique and apply it to a variety of significant paleoanthropological samples. ESR provides a method to date teeth and appropriate categories of stone artifacts which date between ca. 20,000 and possibly as much as 4,000,000 years old. Because both categories of artifacts are common in archaeological sites and because many such occurrences are not datable by other available techniques, ESR, if properly developed, can provide an important anthropological tool. The technique depends on the fact that buried objects absorb small amounts of uranium from the soil and the internal as well as external bombardment by disintegration byproducts creates time dependent displacement of electrons within the sample. ESR provides a method to measure the extent to which this has occurred. When the dose rate has been determined, it is then possible to calculate age. Many prehistoric peoples heated lithics before they fashioned them into tools because the structural changes caused by heating made the material easier to work. Luckily, heat also sets the electron displacement clock to zero thus making heat treated pieces amenable to ER analysis.While it is feasible in principle and has produced intuitively reasonable dates, ESR is not well developed and the results have been treated with understandable caution. Uranium uptake rates are hard to determine and several different models have been proposed. Blackwell and Skinner's research focuses on technique development. They shall conduct a number of experiments to: compare geochemical characteristics of enamel with associated dentine, cementum and adjacent sediments; learn how teeth absorb uranium to provide more accurate uptake models; develop a non-destructive technique which will allow hominid teeth to be dated without loss of valuable evolutionary information; compare external dose rates derived from isochron analysis with those from standard ESR measurements. They will also date samples from a series of anthropologically significant sites.

Bonnie Blackwell和Anne Skinner博士将进行一系列实验室实验，以改进电子自旋共振（ESR）技术，并将其应用于各种重要的古人类学样本。ESR提供了一种方法，以日期牙齿和适当类别的石制品之间的日期约。两万年前甚至可能有四百万年的历史。由于这两类文物在考古遗址中很常见，而且许多此类事件无法通过其他现有技术确定年代，因此ESR如果开发得当，可以提供一个重要的人类学工具。该技术依赖于这样一个事实，即埋藏的物体从土壤中吸收少量的铀，并且内部和外部的衰变副产物轰击会在样品中产生与时间相关的电子位移。ESR提供了一种方法来衡量这种情况发生的程度。当确定剂量率后，就可以计算年龄。许多史前人在将石制品制成工具之前先将其加热，因为加热引起的结构变化使材料更容易加工。幸运的是，热也会将电子位移时钟设置为零，从而使热处理后的工件适合ER分析。虽然它在原理上是可行的，并且已经产生了直观合理的数据，但ESR还没有得到很好的发展，并且结果被谨慎处理。铀的吸收率很难确定，已经提出了几种不同的模型。布莱克威尔和斯金纳的研究集中在技术发展上。他们将进行一些实验，以便：比较釉质与相关牙质、牙骨质和邻近沉积物的地球化学特征;了解牙齿如何吸收铀，以提供更准确的吸收模型;开发一种非破坏性技术，使人类牙齿的年代测定不丢失宝贵的进化信息;比较从等时线分析得出的外部剂量率与从标准ESR测量得出的外部剂量率。他们还将从一系列具有人类学意义的地点采集样本。