Collaborative Research: Beryllium-10 in detrital magnetite as a new tool in erosion and weathering studies

合作研究：碎屑磁铁矿中的铍 10 作为侵蚀和风化研究的新工具

• 批准号: 1148224
• 负责人: Clifford Riebe
• 金额: $ 5.56万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1148224&HistoricalAwards=false
• 关键词: Collaborative; Research; Beryllium; 10; detrital

Cosmogenic Beryllium-10 (10Be) in quartz is widely used to quantify rates of erosion and weathering in landscapes. 10Be is useful in the study of surface processes because it is produced only near the ground surface, and thus provides a measure of the residence time of mineral grains in soils. These residence times can be readily interpreted in terms of erosion rates averaged over hundreds to thousands of years, making them nearly ideal in studies of landscape evolution and soil sustainability. There are problems with the use of quartz, however. It is not present in all landscapes and its chemical preparation requires the use of hazardous hydrofluoric acid, limiting the number of laboratories that are able to process samples. This project will develop 10Be in magnetite as a new tool for determining catchment-averaged rates of erosion and weathering. For most purposes, erosion rates from magnetite would be just as useful as erosion rates from quartz. Magnetite, however, is easier to separate from other minerals and its chemical preparation is far less hazardous and expensive. The project's contributions will include development of rapid, cost-effective mineral separation and chemical preparation techniques. This should open the use of 10Be to a whole new community of researchers. The project will test the method in three landscapes where erosion and weathering rates have been intensively studied. In addition, it will explore the coupled use of 10Be in magnetite and quartz as a new, readily measured index of the catchment-averaged degree of chemical weathering.Not long ago, it was extremely difficult to measure long-term rates of erosion and weathering, in part because the timescales of human observation are usually short compared to the timescales of landscape erosion. Over the last 20 or so years, cosmogenic nuclides such as 10Be in quartz have provided new tools for measuring rates of erosion and weathering averaged over hundreds to thousands of years. This has fueled a revolution in quantitative understanding of surface processes. Yet measurements of erosion rates in some landscapes have remained difficult because the preferred cosmogenic target mineral, quartz, is not present in all rock types. Hence cosmogenic-based erosion rates have rarely been measured in volcanic landscapes, for example. Moreover, all of the work on cosmogenic nuclides is done in just a few dozen labs around the world because quartz is not easy to prepare for analysis of 10Be, and costly, specialized equipment is needed to handle the large volumes of hazardous acids that are involved. Usage of the mineral magnetite has the potential to overcome these difficulties. 10Be is produced within it in much the same way as it is in quartz. It is present as a trace mineral in many rocks where quartz is absent. Moreover, magnetite is easier to separate and dissolve than quartz. Hence, techniques developed in this project promise to open the use of 10Be to new landscapes where quartz is absent, and also to new researchers who lack resources for the specialized equipment of quartz separation and dissolution. Magnetite and quartz weather at different rates. This raises the exciting possibility that 10Be in the mineral pair magnetite and quartz from the same stream will yield an index of chemical weathering in soil. This research will focus on fieldwork at two of NSF's Critical Zone Observatories (Luquillo and Southern Sierra), thus capitalizing on existing infrastructure investment for studying weathering processes and their relationships with geology, climate, and ecology.

石英中的宇宙成因铍 10 (10Be) 广泛用于量化景观中的侵蚀和风化速率。 10Be 可用于研究地表过程，因为它仅在地表附近产生，因此可以测量矿物颗粒在土壤中的停留时间。 这些停留时间可以很容易地用数百年至数千年的平均侵蚀率来解释，这使得它们在景观演化和土壤可持续性研究中几乎是理想的。 然而，石英的使用存在一些问题。 它并不存在于所有景观中，其化学制备需要使用危险的氢氟酸，限制了能够处理样品的实验室数量。 该项目将开发磁铁矿中的 10Be 作为确定流域平均侵蚀和风化速率的新工具。 对于大多数用途，磁铁矿的侵蚀率与石英的侵蚀率一样有用。 然而，磁铁矿更容易与其他矿物分离，并且其化学制备的危险性和成本要低得多。 该项目的贡献将包括开发快速、具有成本效益的矿物分离和化学制备技术。 这将为全新的研究人员群体开放 10Be 的使用。 该项目将在三个景观中测试该方法，对侵蚀和风化率进行了深入研究。 此外，还将探索磁铁矿和石英中 10Be 的联合使用，作为一种新的、易于测量的流域平均化学风化程度指标。不久前，测量长期侵蚀和风化速率极其困难，部分原因是与景观侵蚀的时间尺度相比，人类观察的时间尺度通常很短。在过去 20 多年里，石英中的 10Be 等宇宙成因核素为测量数百至数千年的平均侵蚀和风化速率提供了新工具。这推动了表面过程定量理解的一场革命。然而，测量某些景观中的侵蚀率仍然很困难，因为首选的宇宙成因目标矿物石英并不存在于所有岩石类型中。因此，例如，在火山景观中很少测量基于宇宙成因的侵蚀率。此外，所有关于宇宙成因核素的工作都是在世界各地的几十个实验室中完成的，因为石英不容易准备用于 10Be 分析，并且需要昂贵的专用设备来处理所涉及的大量有害酸。 使用磁铁矿矿物有可能克服这些困难。 10Be 的产生方式与石英中的产生方式非常相似。 它作为微量矿物质存在于许多不含石英的岩石中。 而且，磁铁矿比石英更容易分离和溶解。 因此，该项目开发的技术有望为缺乏石英的新景观以及缺乏石英分离和溶解专用设备资源的新研究人员开放 10Be 的使用。 磁铁矿和石英的天气变化率不同。 这提出了令人兴奋的可能性，即来自同一溪流的矿物对磁铁矿和石英中的 10Be 将产生土壤中化学风化的指数。 这项研究将重点关注美国国家科学基金会的两个关键区域观测站（卢基洛和南塞拉）的实地考察，从而利用现有的基础设施投资来研究风化过程及其与地质、气候和生态的关系。