MAGNETITE MAPPING WITH A MULTICOIL AIRBORNE ELECTROMAGNETIC SYSTEM

A magnetite mapping technique was developed for the horizontal coplanar coils of a closely coupled multicoil airborne EM system. The technique yields contours of apparent weight percent magnetite when using a homogeneous half-space model. The method can be complementary to magnetometer mapping in certain cases. Compared to magnetometry, it is far less sensitive but is more able to resolve closely spaced magnetite zones. The method is also independent of remanent magnetism and magnetic latitude. It is sensitive to . 25 percent magnetite by weight when the sensor is at a height of 30 m above a magnetitic half-space. It can individually resolve steeply narrow magnetite-rich bands which are separated by 60 m.