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.

石英中的宇宙基因铍10（10BE）广泛用于量化景观中的侵蚀和风化速率。 10BE在表面过程的研究中很有用，因为它仅在地面附近产生，因此提供了矿物质在土壤中的停留时间的量度。 这些停留时间可以很容易地用平均数百到数千年的侵蚀率来解释，这使得它们在景观演化和土壤可持续性的研究中几乎是理想的。 但是，使用石英存在问题。 它并非存在于所有景观中，其化学制备需要使用危险的氢氟酸，从而限制了能够处理样品的实验室数量。 该项目将在磁铁矿中开发10BE，作为确定流域平均侵蚀和风化率的新工具。 就大多数目的而言，磁铁矿的侵蚀速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，其化学制备的危险和昂贵也差不多。 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准备技术。 这应该将10BE的用途开放给一个全新的研究人员社区。 该项目将在三个景观中测试该方法，在这些景观中，对侵蚀和风化率进行了深入研究。 此外，它将探索在磁铁矿和石英中使用10BE作为一个新的，很容易测量的化学风化程度的索引。不久前，与人类观察的时间表相比，通常很难衡量长期的侵蚀和风化速率，部分原因是人类观察的时间表通常很短。在过去的20年中，石英中的宇宙核素（例如10BE）提供了新的工具来测量侵蚀速率和数百千年的平均。这引发了对表面过程的定量理解的革命。然而，某些景观中侵蚀率的测量仍然很困难，因为在所有岩石类型中都不存在首选的宇宙靶矿物石英。因此，例如，在火山景观中很少测量基于宇宙的侵蚀率。此外，在世界各地的几十个实验室中，所有关于宇宙核素的工作都是完成的，因为石英不容易准备10BE的分析，并且需要昂贵的专业设备来处理涉及的大量有害危险酸。 矿物磁铁矿的使用有可能克服这些困难。 10be在其中产生的方式与石英中的方式几乎相同。 它是在缺乏石英的许多岩石中作为痕量矿物。 此外，磁铁矿比石英更容易分离和溶解。 因此，该项目中开发的技术有望将10BE使用到缺乏石英的新景观，以及对于缺乏石英分离和溶解专业设备的新研究人员。 磁铁矿和石英天气以不同的速度。 这增加了令人兴奋的可能性，即从同一流中的矿物对磁铁矿中的10BE和石英在土壤中产生化学风化的指数。 这项研究将重点关注NSF关键区观测站（Luquillo和Southern Sierra）的现场工作，因此利用了现有的基础设施投资，用于研究风化过程及其与地质，气候和生态学的关系。