Natural remanent magnetization and thermomagnetic properties of the Allende meteorite

Paleomagnetic examination of a 1-kg specimen of the Allende meteorite has revealed the existence of natural remanent magnetization of constant direction and moderate intensity (3.0 × 10 −4 emu/g). Cooling of the fusion crust in the Earth's magnetic field following atmospheric entry has remagnetized the outer 1 mm of the specimen. Comparison of AC demagnetization spectra of NRM with spectra of laboratory-produced remanence suggests that the natural remanence is thermal or thermochemical remanence formed during original accretion or post-accretion reheating of Allende. Paleointensity determinations on three samples show that the NRM was formed in a field of approximately 1.1 Oe. Thermomagnetic analysis indicates that the ferromagnetic minerals in Allende consist of 95 wt% taenite containing 67% Ni plus 5 wt% taenite with 36% Ni. These iron-nickel minerals amount to only 0.46 wt% of the whole rock.