Genesis of the Neogene to Quaternary volcanism in the Carpathian-Pannonian region; role of subduction, extension, and mantle plume

Neogene to Quaternary volcanism of the Carpathian-Pannonian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. Using the spatial and temporal distribution of the magmatic rocks, their major-and trace-element features, and Sr-Nd-Pb isotope characteristics, we suggest that lithospheric extension in the Pannonian Basin had a major role in the generation of the magmas. Dehydration of subducting slab should have resulted in thorough metasomatism in the mantle wedge during Cretaceous to early Miocene that would have lowered the melting temperature, therefore playing an indirect role in the generation of magmas later on. Mixing between mantle-derived magmas and lower-crustal melts was an important process at the first stage of the silicic and calc-alkaline magmatism in the Northern Pannonian Basin. However, the crustal component gradually decreased with time, which is consistent with magmatic activity in a continuously thinning continental plate. Calc-alkaline volcanism along the Eastern Carpathians was mostly postcollisional and could have been related to slab break-off processes. However, the fairly young (<1.5 Ma) potassic magmatism at the southeasternmost segment of the Carpathian volcanic arc could be explained by lithospheric delamination under the Vrancea zone. Alkaline basaltic volcanism began at the end of rifting of the Pannonian Basin (11 Ma) and continued until recently. We suggest that a mantle plume beneath the Pannonian Basin is highly unlikely and the mafic magmas were formed by small degree partial melting in a heterogeneous asthenospheric mantle, which has been close to the solidus temperature due to the lithospheric extension in the Miocene. Magmatism appears to have been in a waning phase for the last 2 m.y., but recent volcanic eruptions (<200 k.y.) indicate that future volcanic activity cannot be unambiguously ruled out.