Improved Anisotropy of Magnetic Remanence Results from Vectorial Readings Using Novel Refinement Method


 Anisotropy of magnetic remanence (AMR) is typically obtained by imparting a remanence through a sequence of reference directions and subsequent measurement of the remanent magnetic moment with a separate device. This gives rise to potential misalignments which can affect the resultant anisotropy tensor. Vectorial measurements from rock magnetometers are favorable to obtain the best estimate of the anisotropy tensor but make the results highly dependent on the exact knowledge of the reference directions. This can be partly overcome by using the projection of the remanence vector on the reference direction instead of using the full vector in the calculation of the best-fit anisotropy tensor. Since AMR experiments are laborious, it is troublesome to compensate the loss in information with additional measurements. This paper demonstrates an iterative refinement method to recover the original reference directions and therefore to improve the results of AMR experiments by using full vectorial readings. The method works well with a six axis protocol for misalignment of the reference directions up to 25○ and for degrees of anisotropy up to 250%, which covers most experimental and geological cases.