STANDARD CURVES FOR INTERPRETATION OF MAGNETIC ANOMALIES OVER LONG TABULAR BODIES

Abstract

The magnetic anomalies in vertical, horizontal, and total intensity for the thin infinite dike are shown to belong to a single mathematical family of curves for all values of dip and strike of the dike and all values of inclination of the magnetizing field. The complete family of standard curves has been constructed and is incorporated into an interpretational scheme based on superposition with observed magnetic profiles. This technique should give more reliable interpretations than methods based on only a few isolated points of a profile curve. By integration of the general thin‐dike response a general expression of similar form has been derived for thick dikes, and ten sheets of curves for dikes of varying width indices have been constructed. By employing the method of subtraction of curves these serve for constructing anomaly profiles over bodies of finite depth extent. Additionally, for thin dikes the much‐neglected demagnetization corrections have been incorporated in the interpretational method following verification by model studies. One important disclosure of this work is that the depth and location of the apex of an infinite tabular body may be determined without knowing the intensity or direction of magnetization within the body, assuming only that these quantities are constant throughout.