, Auditorium
Earth's magnetic field is generated in Earth's core and plays a vital role in Earth's habitability by shielding us from harmful solar radiation. The past locations of the magnetic poles and the field intensity can be recorded in geologic archives and can help us understand the driving forces behind magnetic field changes such as polarity reversals, low intensity anomalies, and more, to help us better predict the future.
Speleothems can record magnetic field changes from the physical alignment of iron minerals to the ambient magnetic field during the deposition of calcite. These archives are especially useful due to their ability to be chronologically constrained using U/Th series dating. There is an inherent challenge to this work, as samples ideally need to be pure calcite to acquire ages, but must include magnetic material from surrounding rock or soil to acquire paleomagnetic directions. In this study, we have found that speleothems that contain distinctive layers (calcite/detrital material) are best suited to achieve both of these goals. Analysis also allows for environmental interpretation of the hydrologic and geologic system of the cave.
This work is carried out with speleothem samples from previous studies, to minimize impact on caves. Additionally, we hope to aid future researchers in their sampling initiatives, in order to more efficiently use sampled speleothems, and collect fewer samples to better preserve cave environments.
Maggie Brosky, Robert Hatfield, Courtney Sprain, Oana Dumitru, Kaleb McLaughlin