Tertiary collision‐related volcanic rocks of the Eastern Rhodopes (37–25.5 Ma) display calc‐alkaline and shoshonitic affinities, with (A) intermediate to basic and (B) acid compositions. (A) Latites, andesites, also shoshonites and basaltic andesites and scarce basalts, absarokites and ultrapotassic latites were emitted through different eruptive styles: lava flows often autobrecciated, domes, ash and scarce pumice falls and flows. Lahars are frequent. K~2~O contents of intermediate volcanics decrease from North to South towards the collision suture. (B) Rhyolites, trachyrhyolites and trachydacites show explosivity progressively decreasing with time. Several eruptive types can be distinguished: pyroclastic flows (weakly and strongly welded ignimbrite deposits), ash and lapilli falls, domes and lava flows. The large (30×10 km) Borovitza caldera is the result of a paroxysmic explosive phase.
All rocks are characterized by high contents of Rb, Th and Y. Conversely, negative Ba and Ta–Nb anomalies are typical of collision‐related magmatism.
Intense hydrothermal episodes, contemporaneous with the volcanic activity, have converted large amounts of explosive products into bentonite and zeolites deposits. Typical metallogeny is associated with this collision‐related volcanism: large Pb, Zn with Cu and Ag deposits and small U or Au deposits are exposed.