Demagnetization of Ordinary Chondrites under Hydrostatic Pressure up to 1.8 GPa

N. S. Bezaeva, J. Gattacceca, P. Rochette & R. A. Sadykov

Geochemistry International
Published: 09 February 2022


“We present here the results of hydrostatic pressure demagnetization experiments up to 1.8 GPa on LL, L and H ordinary chondrites—the most common type of meteorites with Fe-Ni alloys being the main magnetic carrier. We used a non-magnetic high-pressure cell of piston-cylinder type made of “Russian” alloy (NiCrAl) together with a liquid pressure transmitting medium PES-1 (polyethylsiloxane) to ensure purely hydrostatic pressure. This technique allowed measuring magnetic remanence of investigated samples directly under pressure as well as upon decompression. Pressure was always applied in near-zero magnetic field (<5 μT). The experiments revealed that under hydrostatic pressure up to 1.8 GPa, ordinary chondrites lose up to 51% of their initial saturation isothermal remanent magnetization. Pressure demagnetization degree is proportional to the coercivity of remanence (Bcr), which reflects the magnetic hardness of the samples. This is similar to what was observed for ferrimagnetic minerals others than Fe–Ni alloys. In addition, pressure of 1.8 GPa does not demagnetize samples with Bcr > 80 mT, i.e. whose main metal phase is tetrataenite (Fe0.5Ni0.5). This study gives an overview of pressure sensitivity of ordinary chondrites up to 1.8 GPa and has implications for extraterrestrial paleomagnetism as it can help to interpret remanent magnetization of ordinary chondrites that suffered shock metamorphism processes.”