Novel applications of high-resolution environmental and paleomagnetic imaging

Abstract

This dissertation investigates innovative applications of high-resolution magnetic imaging methods to tackle fundamental inquiries in lunar paleomagnetism, paleoclimatology, and environmental science. Through the utilization of cutting-edge imaging technologies, this research introduces advancements in the recently developed magnetometer, the Quantum Diamond Microscope (QDM), and explores techniques for its application. Moreover, it explores enhancements in magnetic sensitivity and novel avenues for leveraging these technologies to deepen our comprehension of rock magnetism in both terrestrial and lunar contexts. The first chapter of this dissertation centers on the development and advancements of the Quantum Diamond Microscope (QDM). It provides an in-depth exploration into the principles underlying the functionality of the QDM, elucidating its operational mechanisms, and detailing its first earth science research applications. Additionally, the chapter delves into recent upgrades aimed at enhancing the QDM's magnetic sensitivity, thus expanding its capabilities for high-resolution imaging and analysis of magnetic materials. Through this investigation, the dissertation aims to contribute to the broader understanding of state-of-the-art imaging technologies and their potential for transformative impacts in various scientific disciplines. The second chapter of the dissertation delves into the realm of paleomagnetic imaging, exploring new avenues for characterizing the magnetic properties of lunar glass spherules. High-resolution paleomagnetic imaging techniques, including alternating field demagnetization, rock magnetic analysis, and magnetic microscopy, are utilized to investigate magnetic mineralogy, magnetic fabric, and paleomagnetic signals preserved in lunar glasses collected during the Apollo 15 mission. We find two primary categories of magnetic signal, one of which has never been explored before in this capacity. The application of these techniques has the potential to shed light on past lunar dynamo magnetic field variations and current space weathering phenomena. The third chapter explores applying the QDM in a paleoclimate and environmental science context by exploring speleothem-based magnetism as a paleoclimate proxy. By using the quantum diamond microscope (QDM) to obtain a sub-annual resolution time series of ferromagnetic content in a Brazilian speleothem from a well-ventilated cave environment covering the period between 1913 and 2016 CE. This high resolution allows us to quantify the correlation between speleothem magnetic properties and an instrumental precipitation record for the first time. We find that ferromagnetic content in the central column displays a modest but significant negative correlation with rainfall (R^2= 0.35; p=0.0027), while magnetism in the speleothem flanks shows a weaker, statistically insignificant relationship. Rock magnetic analyses of the speleothem further reveal ultrafine, pedogenic grains to be the dominant ferromagnetic carriers. Combining QDM and electron microprobe data, we show that these pedogenic grains were likely developed in surface soils and delivered into the cave as part of airborne, 10 to 200 µm silicate-carbonate soil agglomerates. Our results show that speleothem magnetism holds strong potential as a targeted proxy for paleorainfall and demonstrate a method for identifying the mechanism of magnetic enhancement, which sets the necessary foundation for any paleoclimatic interpretations. In summary, this dissertation presents a comprehensive exploration of high-resolution magnetic imaging techniques and their applications across various scientific disciplines. Beginning with the development and advancements of the Quantum Diamond Microscope (QDM), the research delves into its operational principles and recent upgrades aimed at enhancing magnetic sensitivity. The study then transitions into the realm of paleomagnetic imaging, demonstrating novel approaches for characterizing the magnetic properties of lunar glass spherules. Finally, the dissertation explores the application of QDM in paleoclimate and environmental science, showcasing its utility in speleothem-based paleoclimate proxies. Through these investigations, the dissertation contributes to a deeper understanding of rock magnetism, lunar paleomagnetism, and environmental dynamics, highlighting the transformative potential of high-resolution magnetic imaging methods in advancing scientific inquiry and interdisciplinary research.