New ion microprobe U–Pb zircon ages for the high-K calc-alkaline Blatná suite pinpoint the onset of exhumation of the Moldanubian Unit. Both Blatná and Kozárovice granodiorites (346 ± 2 Ma and 347 ± 2 Ma) were generated by melting of a heterogeneous crust and were emplaced contemporaneously to form the Blatná composite pluton.