U-Pb ages of Proterozoic metaplutonics in gneiss complex of southern Vaermland, south-western Sweden

U-Pb analyses on zircons from three meta-plutonics in the polymetamorphic gneiss complex of south-western Sweden in Vaermland have yielded minimum ages of 1609, 1563 and 1249 Ma. Although the metaplutonics have been strongly reworked, the apparent U-Pb ages of the zircons are almost concordant. This is probably due to low uranium contents. The ages show that many rocks in the 'Pregothian' are age equivalents of better preserved rocks in the Aamaal tectonic mega-unit. It is also concluded that the last deformation, metamorphism and mobilization in the investigated area took place during the Sveconorwegian. (Authors)