THE CALCULATION OF APPARENT SUSCEPTIBILITY AND ITS APPLICATION
Spectra analysis indicates that the distribution of susceptibilities of rocks and minerals can be derived from magnetic measurements. The present paper introduces the principle of the apparent susceptibility calculation. Reduction to the pole, downward continuation and correction of horizontal size of bodies are involved in the calculation. The resultant susceptibility values are comparable with the values measured from actual samples. Several factors which affect the results are discussed and some correction methods are presented. The tech-nigue has been used in the geological interpretation of aeromagnetic surveys in the areas of Precambrian metamorphic rock of the Qian'an district in Eastern Hebei, China and of the Amos-Bar raute area in Quebec, Canada, in both of which helpful information has been obtained. The present study shows that the apparent susceptibility method is a useful tool for regional geological mapping.