New precisely dated pyroclastic deposits from Pliocene-Pleistocene volcanic activity in the central parts of Southeastern Europe

Single-crystal sanidine 40Ar/39Ar dating revealed at least six new explosive eruption events during the 4.0–3.5
Ma and 3.0–2.5 Ma periods in the eruptive history of the Koˇzuf-Voras volcanic system located in the central parts
of Southeastern Europe. The precise ages helped to redefine the timing and eruptive style of the volcanic system,
as the 4.0–2.5 Ma period was previously considered as mainly quiescent, with dominantly lava dome building
activity recognized so far. The pyroclastic layers (mainly massive tuff-lapilli tuff and massive lithic breccia) are
deposited from phreatomagmatic and subplinian eruptions, and block-and-ash flows in the volcano-sedimentary
Mariovo basin, west of the volcanic system. The newly recognized pyroclastic layers could serve as regional
marker layers, as neither their ages nor their geochemical and isotopic (bulk and glass) compositions overlap
with those previously studied tephra layers, either from the Koˇzuf-Voras volcanic system or from other volcanic sources (e.g., Aegean arc). Differences in the geochemical and isotopic data imply sequential evacuation of closely emplaced, discrete, melt-dominant bodies during the older period. In contrast, the younger sequence might represent a compositionally zoned single melt body. The latter also represents an explosive-to-effusive transition as the top layer is a block-and-ash flow unit resulting from a dome collapse.