A moving 3 component fluxgate magnetometer to measure remanent and induced magnetizations in drill core

Abstract

We have developed a 3 component magnetometer which can be drawn along a track to produce a detailed 3 component mapping of a traverse of up to 3 metres length. One of the main applications for this instrument is to rapidly map both remanent and induced magnetizations within drill-core. Continuous sections of up to 2.5 metres of drill core are logged by running the magnetometer along the side of the core. Multiple runs following successive rotations of the core enable separation of fields arising from remanent magnetization (which rotates with the core) from induced magnetization (which does not). A first-pass interpretation of the multi-track data is made using a string of dipoles as equivalent sources. More detailed model inversions are applied if required. Broken sections of core are logged with sufficient gaps between sections that the anomalies from each are well separated