High Spatial Resolution Assessment of the Speleothem Magnetization Proxy

Harvard University, Cambridge MA

Investigators

Abstract

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.