40Ar39Ar^{40}Ar^{39}Ar dating of alkaline lamprophyres from the Polish Western Carpathians

Amphiboles from two types of alkaline lamprophyres from the Silesian Nappe in the Polish Western Carpathians were dated by $^{40}Ar^{39}Ar$ stepwise heating technique. Three teschenite samples representing mesocratic type of lamprophyres yielded similar ages of 122.3±1.6 Ma, while leucocratic lamprophyre represented by a syenite dyke gave 120.4±1.4 Ma date. These ages are interpreted as the time of magmatic emplacement during Early Cretaceous extensional episode within the Silesian Basin. Ages for both types of lamprophyres are identical within error limits, which points to fast (probably ca. 5 Ma) magma evolution from meso to leucocratic stage