The magnetization of a sediment is acquired when ferromagnetic detrital particles align with the Earth's magnetic field as they settle through the water column. The relative continuity and ubiquity of the global sedimentary record makes sediments and sedimentary rocks an ideal target for studies of relative paleointensity (RPI) and the evolution of the Earth's magnetic field. However, processes including flocculation, contact with the substrate, bioturbation, and compaction disrupt this alignment, leading to shallowed remanent inclinations and biased intensities. The inclination of the depositional field also exerts an influence on the remanent intensity, thus affecting RPI estimates and leading to complications in interpretations of the global record. We present a series of 12 deposition experiments conducted in varying field strengths and inclinations, from which we determine RPI estimates. We then correct these estimates using a modified anisotropy-based inclination correction technique. We find experimentally that our correction reduces the inclination dependence of relative paleointensity while preserving the RPI's dependence on the depositional intensity. Our results suggest that the anisotropy-based correction should improve RPI estimates obtained from natural sediments and sedimentary rocks.
Bibliographical noteFunding Information:
This study was funded by NSF grant EAR1447035 to Dario Bilardello. The authors wish to thank colleagues at the IRM for helpful discussions and suggestions. Toshi Yamazaki and Ramon Egli are kindly thanked for their thoughtful and constructive reviews which have significantly improved the manuscript. The data used are listed in the tables and supporting information. This is IRM publication #1705.
© 2018. American Geophysical Union. All Rights Reserved.
- deposition experiments
- detrital remanent magnetization
- inclination shallowing
- magnetic anisotropy
- relative paleointensity
- sedimentary magnetization