A possible break in the Mylonite Zone in Värmland, south-western Sweden

Abstract

All outcrops in a restricted area south of Kil, which interpolation between known outcrops suggests should lie in the Mylonite Zone, show no mylonitic or cataclastic deformation. In the same area more or less sudden changes in topography, lithology, degree of migmatite formation, tectonics, and type of deformation found in the Mylonite Zone occur. It is therefore suggested that there is a break in the Mylonite Zone south of Kil. A hypothesis involving original formation of the Zone at an as yet unknown time and later hinge faulting is put forward. The hinge is located at the break. North of the break the original Zone more or less coincides with the later fault but south of the break the later faulting occurred to the west of the ‘original Mylonite Zone’ and coincides with the Mylonite Zone as it appears on published maps.

Key Words:

• Mplonite Zone
• Western Pregothian mega-unit
• Eastern Pregothian mega-unit
• Hammarön formation
• mylonite
• microbreccia
• hinge fault
• genesis
• π diagrams
• Proterozoic
• Kil
• Norsälven
• Värmland
• south-western Sweden
• N5920 N5934 E1323 E1311