Collaborative Research: Identifying the Limitations and Expanding the Utility of Detrital Mineral U-Pb Geochronology to Tectonic Studies

合作研究：确定碎屑矿物 U-Pb 地质年代学的局限性并扩展其在构造研究中的应用

• 批准号: 0635688
• 负责人: David Moecher
• 金额: --
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635688&HistoricalAwards=false
• 关键词: Collaborative; Research; Identifying; Limitations; Expanding

Provenance studies utilizing radiometric ages of detrital minerals (particularly zircon) have expanded greatly over the past decade, driven largely by advances in microgeochronometric methods. The very same properties that make zircon such a powerful geochronometer (extremely high closure temperature and very low solubility) render it virtually inert during collisional orogenesis, except at upper amphibolite to granulite facies and anatexis. Thus, an entire cycle of collision, crustal thickening, heating and loading, and exhumation could pass in some terranes and there would be no record of that cycle in the detrital record using conventional approaches for detrital zircon analysis. This research project is testing the utility of determining the Uranium-Thorium-Lead ages of detrital monazite, which holds the potential for providing a far richer history of tectonometamorphic events compared to analyzing only detrital zircon cores. Additionally, the hypothesis that very small detrital zircon crystals, and thin metamorphic rims on detrital zircon, provide a substantially different chronological view of an orogen compared to that obtained by analyzing the central portions of larger grains is being tested. Clastic sedimentary rocks and alluvium from the southern Appalachians are being sampled for their heavy mineral suites. The Appalachian orogen is chosen because this belt has experienced the full spectrum of tectonic processes, rather than being constructed largely by a single process such as arc magmatism. In addition, to fully test these hypotheses it is necessary to collect the detrital data from a region where the details of the magmatic, metamorphic, and deformational history are well established. This will allow establishment of the most robust protocols to minimize the effects of age bias, both those naturally inherent to detrital minerals, and potential laboratory induced bias during grain selection. Only once the results of detrital age information are available from a well-studied, polydeformed orogen can they be best applied to tectonic studies of other more poorly understood orogenic belts. The results of this study will have major implications for the interpretation of the worldwide detrital mineral age record. The procedures and tools developed here that are most successful for resolving the problems that currently exist with the interpretation of the conventional detrital zircon database will then be available for application by other researchers working in any orogenic belt, for any division of geologic time, to best use detrital mineral dating as a provenance indicator, as an aid in plate reconstructions, and for much more accurate elucidation of major terrane tectonothermal events.

在过去的十年中，利用碎屑矿物（尤其是锆石）的辐射年龄的出处研究大大扩展，这在很大程度上取决于微地质学方法的进步。使锆石成为如此强大的地球体经济体（极高的闭合温度和非常低的溶解度）的相同特性使其在碰撞造成造成过程中实际上是惰性的，除非在上闪石上颗粒状的相和厌食。因此，整个碰撞，地壳增厚，加热和负荷以及挖掘的循环可能会传播到某些地面，并且使用常规方法进行碎屑锆石分析，在碎屑记录中没有记录该循环的记录。该研究项目正在测试确定碎屑独居石的铀 - 硫铅铅年龄，该铀铅含量与仅分析碎屑锆石核心相比，提供了更丰富的构型型事件历史的潜力。此外，与分析较大晶粒的中央部分相比，造成造山机的碎屑锆石晶体非常小的假设和碎屑锆石上的薄变质边缘提供了基本不同的时间。阿巴拉契亚岛南部的碎屑沉积岩石和冲积岩和冲积物正在为其重型矿物套房采样。之所以选择阿巴拉契亚造山基因，是因为该皮带经历了各种构造过程，而不是主要是通过诸如弧岩浆等单个过程来构建的。此外，为了充分检验这些假设，有必要从岩浆，变质和变形史细节的区域收集碎屑数据。这将允许建立最强大的方案，以最大程度地减少年龄偏见的影响，既是碎屑矿物质自然固有的，又是潜在的实验室诱发的偏见。只有一旦从良好的，多塑造的造山机中获得碎屑年龄信息的结果，才能最好地应用于对其他知名度较差的造山带的构造研究。这项研究的结果将对全球碎屑矿物年龄记录的解释产生重大影响。此处开发的程序和工具最成功地解决了当前存在的问题，这些问题将在传统的碎屑锆石数据库中解释，然后将在任何造山带上工作的其他研究人员提供任何地质时间的研究人员，以最好地将碎屑矿物矿物矿物质代表作为出处指标，以帮助更加精确地进行plate bectuctions of Plate Repstructions和更加精确的大事。