Collaborative Research: Improved Geochronology-Based Sediment Provenance Analysis Through Physico-Mechanical Characterization of Zircon Transport

合作研究：通过锆石运移的物理机械表征改进基于地质年代学的沉积物物源分析

• 批准号: 1946496
• 负责人: Alexander Pullen
• 金额: $ 19.59万
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1946496&HistoricalAwards=false
• 关键词: Collaborative; Research; Improved; Geochronology; Based

The generation and movement of sediments by wind and water currents are fundamental geologic processes that have shaped the surface of our planet for billions of years. Through these processes, material removed from higher elevation areas by weathering and erosion is mechanically transported to lower elevation regions (i.e., basins), thereby leveling topographic highs (e.g., mountains). Studying and understanding these processes in a quantitative way provides Earth Scientists with fundamental information about geography, evolution, human migration, climate, tectonics, and the development of economically important sedimentary basins. One of the most robust ways to study sediment transport in modern and ancient sedimentary systems (e.g., rivers, deserts), is by measuring the geologic ages of weathering-resistant minerals such as zircon that contain radioactive parent and daughter isotopes. By studying the age patterns of far-travelled zircons, Earth Scientists can draw linkages to potential source areas with comparable ages and reconstruct ancient sediment routing systems. Students will be trained in the research methods and a new Creative Inquiry course for undergraduates will be developed as part of the project.Studying sediment transport through age-dating of detrital minerals is not without complexities and potential biases. Although the mechanical sorting and fractionation of particles carried by tractive currents have been well-known processes in sedimentology for well over a century, our knowledge of how sediment transport affects detrital zircon populations and influences U-Pb age spectra remains critically inadequate. Using fluvial systems as natural laboratories, this project will quantify the effects that the physical characteristics of zircon, such as grain size, morphology, and accumulated radiation damage, have in systematically biasing detrital zircon age spectra during transport. This project will: 1) collect robust age and physical-properties information of detrital zircon fractionation during transport, and 2) apply methods of statistical inference to quantify the latent effects these physical characteristics have in biasing the observed age spectra. These insights will allow Earth Scientists to perform more ‘geologically informed’ inter-sample comparisons, enhancing the accuracy of tectonic reconstructions, quantitative provenance models, and sediment-transport pathways derived from detrital zircon U-Pb data. The code developed will be user friendly and available to other researchers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

风和水流产生和移动的沉积物是数十亿年来塑造地球表面的基本地质过程，通过这些过程，通过风化和侵蚀从高海拔地区去除的物质被机械地输送到低海拔地区。定量研究和理解这些过程为地球科学家提供了有关地理、进化、人类迁徙、气候、构造和发展的基本信息。研究现代和古代沉积系统（例如河流、沙漠）中沉积物迁移的最有效方法之一是测量含有放射性母体和子体的抗风化矿物（例如锆石）的地质年龄。通过研究遥远的锆石的年龄模式，地球科学家可以与年龄相当的潜在源区建立联系，并重建古代沉积物路线系统。作为该项目的一部分，将为本科生开发新的创意探究课程。尽管牵引流携带的颗粒的机械分类和分馏已众所周知，但通过碎屑矿物的年龄测定来研究沉积物迁移并非没有复杂性和潜在的偏差。尽管我们对沉积学过程进行了一个多世纪的研究，但我们对沉积物迁移如何影响碎屑锆石种群和影响 U-Pb 年龄谱的了解仍然严重不足，该项目将利用河流系统作为自然实验室。量化锆石的物理特征（例如晶粒尺寸、形态和累积辐射损伤）对运输过程中碎屑锆石年龄谱的系统偏差的影响。该项目将：1）收集碎屑锆石的可靠年龄和物理性质信息。运输过程中的分馏，2）应用统计推断方法来量化这些物理特征对观测到的年龄谱的潜在影响。这些见解将使地球科学家能够更加“地质”地进行工作。知情的样本间比较，提高了构造重建、定量起源模型和源自碎屑锆石 U-Pb 数据的沉积物传输路径的准确性。开发的代码将是用户友好的，可供其他研究人员使用。该奖项反映了 NSF 的法定规定。使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。