The Magnetization Vector became important in Surface Geology and Chromite Prospecting within Ultramaphic Massifs

Abstract

Ground-based magnetic survey was performed on two ultramaphic massifs, Albania, mapping magnetic anomalies possibly connected with tectonic and cumulate sections, grade of horst rocks serpentinization and/or shallow chromite deposits of variable size. The results were contradictory. We have implemented a scheme and computer code for contouring rock surface with abnormal magnetization utilizing the simplicity of magnetic bell shaped field anomaly with so-called vertical and the analytic signal for the 2-d thin sheet model. Rapid estimations for the edge of the sources, depth, intensity and angle of total magnetization for the observed shallow anomalies surveyed-line data are obtained. As an alternative of filtering technique we have used the magnetic computed field intensity map of the area with constrained source parameters. The computed magnetic field anomaly map with magnetization vector collinear within the range revealed from chromite laboratory measurements show characteristic, which hardly notices in the survey magnetic anomaly map. The predicted magnetic data on an area 4 km2 are well correlated with the shallow deposits or surface occurrences or controlled associated structures in the harzburgite host rocks. Image of total magnetization inclination data derived from ground magnetic survey acquired over a 30 km2 resembles the geology than the total field magnetic anomaly map. These data show that the total magnetization of thick residual dunites, rich in basaltic impregnation, reveals an opposite direction data against the underlain harzburgite rocks.