Original paper

Field mapping of magnetic susceptibility as tool for petrographic characterization of granitoids a key study in the Hauzenberg pluton, Bavarian Forest, Germany

de Wall, Helga; Dietl, Carlo; Streit, Verena; Rückert, David; Rohrmüller, Johann

Abstract

In the Hauzenberger pluton of East Bavaria two granites, (Hauz I and II) and a granodiorite are distinguished. Their magnetic susceptibility, measured in the field using a portable susceptometer, is low, but clear differences appear between the granodiorite (84 × 10−6 SI) and both granite types (52 × 10−6 SI). These differences are related to the variable content in biotite and muscovite. Based on systematic magnetic susceptibility measurement at 372 sites, a susceptibility contour map of the Hauzenberg pluton was drawn. There is a good agreement between the spatial distribution of the different lithotypes of the pluton and the areas of iso-susceptibility values. Susceptibility measurements on rock-floats can be considered as reliable in the frame of the contoured susceptibility map, thus allowing the implementation of float data sets into the magnetic susceptibility mapping routine.