Effect of post-magmatic processes on magnetic fabric of teschenite association rocks of the Outer Western Carpathians
Abstrakt
Volcanic and subvolcanic alkaline rocks of the teschenite association of the Outer Western Carpathians are characterized by intensive late magmatic, post-magmatic, and also hydrothermal changes that modified their composition not only in rock-forming minerals, but also in accessory magnetic minerals (magnetite, titanomagnetite, maghemite) as indicated by magnetic susceptibility ranging from 10(-5) to 10(-1) SI units. The magnetic fabric of the most sills and dykes investigated is very roughly conformable to the shapes of the bodies corresponding to the most common type of magnetic fabric in dykes and sills, which no doubt originates through magma flow.
However, the fabric shows large variation, much larger than expected for volcanic magnetic fabric, which can be ascribed to late magmatic or post-magmatic alterations of magnetic minerals diminishing the magnetic fabric homogeneity. Even though the teschenite association rocks occur in the sole part of the Silesian thrust sheet, their magnetic fabric and that of host sedimentary rocks show only very weak indications of ductile deformation.
Consequently, the Silesian thrust sheet responded to the tectonic movements creating thrust sheet structure by faulting and thrusting of the deformed zones and not by ductile deformation of the bulk of the thrust sheet.