Developing Heavy Stable Isotopes for Provenance of Turquoise, Metals and Glass

开发用于绿松石、金属和玻璃来源的重稳定同位素

• 批准号: 0852270
• 负责人: David Killick
• 金额: $ 26.98万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0852270&HistoricalAwards=false
• 关键词: Developing; Heavy; Stable; Isotopes; Provenance

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).With the support of the National Science Foundation, an interdisiplinary team at the University of Arizona will greatly expand work in progress on characterizing (1) sources of turquoise in the southwestern USA and northern Mexico; (2) sources of native copper in north America; (3) sources of copper in North and West Africa; and (4) glass trade beads of the Muslim era in Africa. The team consists of an archaeologist (David Killick), two geochemists (Joaquin Ruiz and John Chesley) and three graduate students (Thomas Fenn, Lisa Molofsky and Alyson Thibodeau).Some of the inorganic materials that were highly valued by past societies are both geologically scarce and unevenly distributed across the earth's surface. For example, Mesopotamia and the West African Sahel both have few copper ore deposits, and thus the populations of these regions had to obtain almost all of the copper that they consumed through long-distance trade. Turquoise only forms around copper ore deposits in semi-arid areas, but is often recovered from archaeological sites in regions where there are no local sources, such as Mesopotamia and central Mexico. These materials (and others, like obsidian, tin and jade) are therefore potentially valuable indicators of the extent, duration and scale of prehistoric contacts between distant regions. Actual proof of long-distance exchange can only be obtained by matching the chemical or mineralogical composition of archaeological artefacts to the composition of specific geological sources of these materials (the field of provenance analysis). A necessary first step is to demonstrate that all potential sources of these materials can in fact be distinguished from each other on chemical or mineralogical evidence. The methods most commonly employed for provenance analysis (trace element ratios, optical petrography and x-ray diffraction) are not likely to be fully successful in distinguishing copper and turquoise deposits, which are highly variable aggregates of copper minerals and host rocks. This study will rely instead upon the measurement of isotopic ratios of lead and strontium. Ratios of these isotopes are less variable within particular deposits than are trace element ratios, are not altered by weathering or smelting, and can often be related to regional geological processes (e.g. the assembly of subcontinents from terranes). Copper isotope ratios will also be used as a third line of evidence in some cases.The broader impacts of these studies will depend upon the empirical findings. If turquoise sources can be successfully discriminated from each other, archaeologists will have a powerful new way of investigating prehistoric interaction between Mexico and the southwestern USA. Similarly, if the geological sources of copper alloys and glass beads in archaeological sites in West Africa can be reliably inferred from isotopic and chemical composition, archaeologists will be able to study in some detail the early history of contacts between the Muslim world and sub-Saharan Africa - a topic of very wide popular interest, given that one-third of the population of Africa today are Muslims.

该奖项是根据2009年美国复苏和再投资法案资助的（公法111-5）在国家科学基金会的支持下，亚利桑那大学的一个跨学科小组将大大扩展正在进行的表征（1）美国西南部和墨西哥北方绿松石来源;（2）北美自然铜来源;（3）美国北部绿松石来源。（3）北非和西非的铜资源;（4）非洲穆斯林时代的玻璃贸易珠。该团队由一名考古学家（大卫基利克）、两名地球化学家（华金·鲁伊斯和约翰·切斯利）和三名研究生（托马斯·芬恩、丽莎·莫罗夫斯基和艾莉森·蒂博多）组成。一些被过去社会高度重视的无机材料在地质学上既稀少，又不均匀地分布在地球表面。例如，美索不达米亚和西非萨赫勒地区的铜矿储量都很少，因此这些地区的人口必须通过长途贸易获得几乎所有的铜。绿松石只在半干旱地区的铜矿周围形成，但通常在没有当地来源的地区，如美索不达米亚和墨西哥中部的考古遗址中发现。因此，这些材料（以及其他材料，如黑曜石，锡和玉）是遥远地区之间史前接触的范围，持续时间和规模的潜在有价值的指标。远距离交换的实际证据只能通过将考古文物的化学或矿物成分与这些材料的特定地质来源的成分相匹配来获得（来源分析领域）。必要的第一步是证明这些材料的所有潜在来源实际上都可以根据化学或矿物学证据相互区分。 用于物源分析的最常用的方法（微量元素比值、光学岩相学和X射线衍射）不太可能完全成功地区分铜和绿松石矿床，这是铜矿物和寄主岩石的高度可变的集合体。 这项研究将依赖于铅和锶的同位素比率的测量。这些同位素的比值在特定矿床中的变化比微量元素的比值小，不会因风化或熔炼而改变，并且通常与区域地质过程有关（例如，次大陆从火山岩的组装）。 在某些情况下，铜同位素比值也将被用作第三条证据线，这些研究的更广泛影响将取决于实证结果。如果绿松石来源可以成功地相互区分，考古学家将有一个强大的新方法来调查墨西哥和美国西南部之间的史前互动。类似地，如果西非考古遗址中铜合金和玻璃珠的地质来源可以从同位素和化学成分中可靠地推断出来，考古学家将能够详细研究穆斯林世界和撒哈拉以南非洲之间接触的早期历史--考虑到今天非洲三分之一的人口是穆斯林，这个话题引起了广泛的兴趣。