Magnetic Recording Stability of Taenite-Containing MeteoritesOPEN ACCESS
José A. P. M. Devienne, Thomas A. Berndt, Wyn Williams, Lesleis Nagy
Geophysical Research Letters
Volume 50, Issue12
28 June 2023
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“Key Points
- Nanometer-scaled taenite observed in different meteoritic microstructures are magnetically stable over billion-years timescales
- Taenite-containing cloudy zones are dominates by uniform states able to record stable magnetizations as grains grow through ∼14 nm
- Vortex states observed in larger (>50 nm) taenite grains are also highly stable, but may be reset upon tetrataenite ordering”
“Sub-μm taenite and tetrataenite grains observed in a number of (stony-)iron meteorite groups are promising sources of paleomagnetic records in meteorites. While slowly-cooled meteorites form tetrataenite—an extremely good recorder—, fast-cooled meteorites may contain fine-grained taenite, which was considered unsuitable for paleomagnetic studies. In this work, however, we show that nm-sized taenite grains are stable over billion-year timescales, indicating that taenite-bearing meteorites are reliable sources of paleomagnetic information. We find a range of sizes for which taenite forms stable single-domain structures, which coincides with the grain sizes observed in the cloudy zone of most fast cooled IVA meteorites. These meteorites, therefore, can provide reliable paleomagnetic information recorded as a stable crystallization remanent magnetization as taenite grains grown. Vortex states observed in larger (>50 nm) grain sizes are also highly stable, indicating that coarse-grained taenite observed in meteoritic microstructures can also provide reliable records of paleomagnetic fields.”
