ANIZOTROPIE MAGNETICKÉ SUSCEPTIBILITY HORNIN NA KONTAKTU METABAZITOVÉ A DIORITOVÉ ZÓNY BRNĚNSKÉHO MASIVU V OKOLÍ VELKÉ BABY U JINAČOVIC

Abstract

An anisotropy of magnetic susceptibility and temperature dependence on magnetic susceptibility were used to reveal an evolution history along the contact of the Metabasite and Diorite zones of Brno massif north of Brno-Řečkovice. The analysis of temperature dependence of magnetic susceptibility indicated that magnetic properties of all rocks in this area are essentially controlled by magnetite with a very small contribution of pyrhotite and hematite. These minerals were formed later than the primary magmatic minerals. Therefore we assume that magnetic fabrics in studied rocks reflect deformational processes which affected these rocks. There are three patterns in anisotropy of magnetic susceptibility (AMS) in studied rocks. In the first pattern detected in diorites, the magnetic foliation is striking NE–SW, dipping to the NW and there is subvertical magnetic lineation. The second planar magnetic indicates a rotational movement of microgranite rocks along the contact of the Metabasite and Diorite zones. The last pattern found in rocks of the Metabasite zone is magnetic foliation striking NNE–SSW dipping on the NWW and magnetic lineation trending to the SW with plunge of 42° and it shows normal faulting of studied area.