High Spatial Resolution Assessment of the Speleothem Magnetization Proxy

这项研究旨在量化洞穴中磁化作用作为过去降雨指标的可靠性。具体地说，研究人员的目标是研究降雨和磁性粒子沉积之间的物理机制。这项工作将利用最近的技术进步，允许使用量子钻石显微镜进行高分辨率的磁场成像。对洞穴的分析可以提供关于古代气候条件的准确的、高分辨率的记录。然而，过去降雨量最常用的替代品受到多重和相互竞争的影响，导致潜在的模棱两可的解释。最近的研究表明，洞穴的磁性，特别是洞穴的磁化强度，有望成为当地水气候的档案。然而，除降雨以外的多种过程都可能导致磁性粒子的富集化。因此，了解区域水文气候和洞穴水文如何影响洞穴中磁性颗粒的富集机制，是洞穴磁性作为古代降水示踪剂广泛应用的先决条件。研究框架包括三项任务：1)利用观测记录直接评估降雨-磁化关系；2)使用重复样本测试降水信号的重现性；3)洞穴监测活动，以表征磁性粒子的通量及其对记录的水文条件的依赖。潜在的更广泛的影响包括开发一种新的过去降雨变异性的示踪剂，以加强古气候重建。研究人员将为高中生和他们的老师组织以气候为主题的实地考察活动。实地考察将包括哈佛自然历史博物馆的气候展览和马萨诸塞州韦茅斯的大埃斯克尔公园和马萨诸塞州林肯的德拉姆林农场的冰川特征。学生们将完成动手活动，如测量esker和鼓的尺寸。外展活动还将通过哈佛实验室交换倡议，让学生和他们的老师参与数据分析。该项目中量子钻石显微镜产生的磁性图像将向学生和教师开放，让他们积极参与该项目的研究活动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This research aims to quantify the reliability of magnetization in speleothems as an indicator of past rainfall. Specifically, the researchers aim to investigate the physical mechanism that link rainfall and the deposition of magnetic particles. The work will take advantage of recent technological advances that permit magnetic field imaging at high resolution using the quantum diamond microscope. Analyses of speleothems can provide well-dated, high-resolution records of ancient climate conditions. However, the most used proxies for past rainfall are influenced by multiple and competing effects, resulting in potentially ambiguous interpretations. Recent studies have shown that speleothem magnetism, specifically, the intensity of speleothem magnetization holds promise as an archive of local hydroclimate. However, multiple processes other than rainfall can lead to the enrichment of magnetic particles. Therefore, understanding how regional hydroclimate and cave hydrology impact the mechanism of magnetic particle enrichment in speleothem is a prerequisite for the broad usage of speleothem magnetism as a tracer of ancient precipitation. The research framework consists of three Tasks: 1) Direct evaluation of the rainfall-magnetization relationship using observational records; 2) Testing reproducibility of a precipitation signal using duplicate samples; and 3) Cave monitoring campaign to characterize fluxes of magnetic particles and their dependence on recorded hydrological conditions.The potential Broader Impacts include developing a new tracer of past rainfall variability to enhance paleoclimate reconstructions. The researchers will organize outreach activities that consist of Climate themed fieldtrips for high school students and their teachers. The fieldtrips will include the climate exhibit at the Harvard Museum of Natural History and glacial features at the Great Esker Park in Weymouth, MA and Drumlin Farms in Lincoln, MA. The students will complete hands-on activities such as measuring the dimensions of the esker and drumlin. The outreach activities will also involve the students and their teachers in data analyses through the Harvard LabXchange initiative. The magnetic images generated by the quantum diamond microscope in this project will be made accessible for students and teachers to actively participate in the research activities of this project.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.