Remanent Magnetisation

Remanent magnetisation is just as important a component as induced magnetisation (arising from magnetic susceptibility) in controlling the total (i.e., induced + remanent) magnetization strength and direction in geological bodies. Where magnetised rocks have a high Koenigsberger (Q) ratio (i.e., a high ratio of remanent to induced magnetization), and where the remanent magnetisation direction is significantly oblique to the inducing field, anomalies will be incorrectly modelled if they do not account for the remanent magnetisation.

CSIRO uses an AGICO JR-6 spinner magnetometer (Figure 3) for measuring remanent magnetisation. The JR-6 is the world’s most sensitive and accurate instrument for measurement of remanent magnetization of rocks based on classical (non-cryogenic) principle and is the standard for palaeomagnetism world-wide. The JR-6A  is paired with an LDA5 AF Demagnetiser and/ or a rock oven for thermal demagnetisation experiments.