The Western Carpathians crystalline basement recorded common indications of the Cadomian/Avalonian basement precursors. There the pre-Mesozoic basement of the Tatric Unit was studied with respect to its lithological, structural, metamorphic and age characteristics. The obtained data proves that this basement is made of two different rock complexes—the older Lower Étage (Cambrian to Silurian) showing high-grade metamorphic evolution, and the younger Upper Étage (Upper Silurian to Devonian) presenting low-grade metamorphism and younger stage of development. First representative U–Th–Pb detrital zircon data from metamorphosed siliciclastics from the Tatric Unit of the Western Carpathians indicate a general dominance of Neoproterozoic—mainly Ediacaran source rocks. The latter are interpreted to have been located at the Cadomian arc supplied mostly from the Saharan Metacraton. Combined with less frequent Archean and Paleoproterozoic zircon populations a common Gondwanan provenance derived from reworked West African Craton is proposed for part of the samples. However, some samples contain Mesoproterozoic detrital zircons what is typical for the Avalonian microcontinent. The studied metamorphic rocks are interpreted to originate from the Rheic Ocean and also partly from the Rheno-Hercynian basin. Indeed, significant differences in the metamorphic evolution of both metamorphic rock assemblages suggest their present juxtaposition and or their thrusting during the Late Devonian to Carboniferous (Visean) Variscan subduction/collision processes.