Petrography and geochemistry of the Sredogriv metamorphites, NW Bulgaria

The petrological and geochemical data for the Sredogriv metamorphics determine protoliths of metaconglomerates and metasandstones with varying clay content and a significant amount of acidic igneous fragments. The geochemistry, geochronology, and mineralogy of these lithic clasts coincide with the exposed in the close vicinity allochthonous Neoproterozoic–Cambrian orthometamorphic bodies (Protopopintsi metagranite). The tectonic discrimination diagram defines a continental island arc tectonic setting simultaneously with the accretion of peri-Gondwanan fragments to the Balkan Ensemble followed by the development of the Early Silurian–Devonian epicontinental basin.