Radiometric dating of Precambrian rocks in Småland, southeastern Sweden

Abstract
Dating of zircons with the U-Pb method in southeastern Sweden gives ages of 1837 Ma on volcanics, considered as postorogenic to the Svecokarelian, and 1825 Ma on an arkose (possibly a sheared synorogenic granite). These figures coincide with previous U-Pb ages in southeastern Sweden. Zircons from an older preorogenic gneiss and a metasediment do not fit a U-Pb discordia line but imply a previous history back to 2500 Ma ago. Zircons from a dike porphyry intruding the ‘younger’ volcanics do not yield a meaningful age, probably due to contamination. When compiling the presented U-Pb data with previous Rb-Sr and K-Ar ages the orogenic activity from synorogenic through postorogenic times seems to be continuous in southeastern Sweden.