Planetary Paleomagnetic Intensity Recording Fidelity Test Using a Synthetic Lava

Abstract

Meteorite paleomagnetism is fundamental to understanding planetary dynamo processes and the evolution of the early Solar System. However, due to the extraterrestrial and ancient origins of meteorites, their paleomagnetic recording fidelity remains uncertain, which can be tested from a planetary sample formed in a known field. On Earth, historic lavas are used to examine paleomagnetic recording fidelity through the Thellier-series experiment and other paleointensity methods, which can produce paleointensity estimates to test against the known field strength. But natural terrestrial rocks have different magnetic mineralogy from planetary samples, so they cannot faithfully infer the recording fidelity of meteorites. Here, we used an iron-particle-bearing sample from the Syracuse University Lava Project (SULP), which is analogous to the lunar basalts and howardite-eucrite-diogenite meteorites and forms in the present-day Earth's field, to investigate the recording fidelity of these meteorites. No remanence has been identified in the high coercivity range with alternating field (AF) demagnetization due to the sample's low coercivity and AF noise, which produces underestimated paleointensities. Two accurate thermal paleointensities indicate that we may acquire accurate paleointensities from non-ideal multidomain (MD) iron grains with the Thellier-Coe and RESET methods, but the success rate is low due to the MD effect and thermal alteration in the experiments. Our results imply that MD iron-bearing meteorites have the potential to provide accurate paleointensities that can be used to constrain planetary processes.