Paired uraninite and molybdenite dating of the Konigshain granite: implications for the onset of late-Variscan magmatism in the Lausitz Block

We present geochronological data for late-Variscan magmatism in the Lausitz Block of the Saxo-Thuringian Zone, Germany. The Th-U-total Pb age of uraninite and the Re-Os age of molybdenite from the composite biotite-monzogranite pluton of Konigshain overlap at the 2 sigma confidence limit: 328.6 +/- A 1.9 Ma (uraninite), and 327.0 +/- A 1.3 Ma and 327.6 +/- A 1.3 Ma (molybdenite), indicating that crystallization of magmatic uraninite and deposition of molybdenite were nearly contemporaneous. These data imply that magmatic processes in this part of the Variscan orogen already started in latest Visean time, about 10 Ma earlier than previously assumed (315-320 Ma). The new ages correspond to ages for plutonic rocks in the Elbe Zone immediately west of the Lausitz (around 335-325 Ma) and the bulk of late-Variscan igneous rocks in the Saxo-Thuringian Zone (335-320 Ma).