Palaeomagnetism and magnetic properties of Tertiary basaltic rocks from Gracze, Lower Silesia

Abstract

The Tertiary basaltic rocks of Gracze near Opole, Lower Silesia (Poland), .belong to the Eastern extremity of the Central European volcanic province and are part of the Bohemo-Silesian belt. They are represented by melanocratic type of nepheline basanite (melabasanite) with local transitions to ankaratrite, and occur as plugs, vent fills of craters and larva flows. The present paper details: (a) palaeomagnetic investigations based on the determination of directions of the natural remanent magnetization of rocks (NRM) and their magnetic stability; (b) investigations of magnetic properties of basaltic rocks as related to their mineral content. The latter include measurements of changes in saturation parameters as a function of temperature; determination of Curie points; determination of Fe and Ti contents in the magnetic fraction; and microscopic analysis of polished sections in reflected light.