Dykes of melagranite porphyry corresponding in geochemistry to acid varieties of durbachitic plutonic rocks were emplaced post-tectonically into granitoids of the Central Bohemian Plutonic Complex (CBPC) and gneisses to migmatites of the Moldanubian Zone adjacent to S contacts of the CBPC. U-Pb dating of zircon from one typical dyke resulted in crystallization age of c. 338 Ma.
Emplacement of porphyry dykes thus represents the final stage of durbachitic igneous activity but precededd another intrusive pulse of ultrapotassic magmas represented by petrographically distinct biotite-two-pyroxene syenitoids of the Tábor and Jihlava plutons.