Records of past geomagnetic field behavior offer a window into the behavior of the Earth's convecting outer core, and lead to a better understanding of geodynamo processes that generate Earth?s magnetic field. This project aims to develop a relatively untapped reservoir of paleomagnetic and rock magnetic information, speleothems (e.g., stalagmites, and flowstone). Speleothems have immense potential for archiving high quality, high resolution geomagnetic records, and can be dated with supreme precision using radiometric techniques. This research investigates the fundamental processes involved in natural remanence acquisition in speleothems using rock magnetic and microscopic imaging techniques, and establishes chronological constraints for geomagnetic field behavior during specific periods in the last 130 ka.
The overarching goal of this research project is to construct high-resolution records of geomagnetic field behavior and paleoclimate conditions using the iron oxide mineral assemblages preserved within speleothems. We will address both the mechanical transport and chemical precipitation of iron oxide minerals in speleothems in order to better understand how and when speleothems acquire a recording of the Earth's magnetic field. Recent instrumental progress provides the sensitivity and sample handling capabilities needed to collect a rich variety of magnetic measurements from speleothems, at an unprecedented spatial resolution. The investigation of speleothem magnetization on a sub-millimeter scale will advance the understanding of magnetic processes in speleothems, ranging from changing dripwater conditions to episodic flooding that can be used to produce regional paleohydrology records. Precisely dated, high fidelity paleomagnetic records from speleothems will help better constrain time-dependent, global geomagnetic field models. An additional benefit of having detailed, high-precision chronologies of paleomagnetic variations is that the chronological information can be transferred to existing deposits with correlatable paleomagnetic records, but with less constrained age models (e.g., archaeological sites, and/or sediment cores). High resolution geomagnetic fluctuations recovered from speleothems will contribute valuable information to geodynamo models that focus on small-scale core flow dynamics. The environmental magnetic records of speleothems will bridge the gap that exists between climatic and environmental interpretations from traditional speleothem measurements such as oxygen isotopes, and the environmental magnetic records of other depositional environments.
