Abstract
The cloudy zone (CZ), a nm-sized intergrowth of taenite or tetrataenite
crystals (or islands), is the most promising phase to preserve
palaeomagnetic records in (stony-)iron meteorites. While slowly-cooled
meteorites form tetrataenite – an extremely good recorder –
fast-cooled meteorites contain fine-grained taenite islands, which were
considered unsuitable for palaeomagnetic 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. Additionally, we find a range of
sizes for which taenite forms stable single-domain structures.
Single-domain states might be preserved even through subsequent
tetrataenite ordering, implying that tetrataenite might carry
magnetization state inherited from its precursor taenite. This remanent
magnetization can be up to 10\textsuperscript{5} years
older than that of larger tetrataenite islands in the same meteorite,
which would have been reset upon ordering. This allow studding to two
distinct events of planetesimal formation from a single sample.