Morphometrical and geochronological constraints on the youngest eruptive activity in East-Central Europe at the Ciomadul (Csomلd) lava dome complex, East Carpathians

The timing of Late Pleistocene volcanic activity of the Ciomadul (Csomád) dacitic lava dome complex, site of the youngest eruptions in the Carpathians, has been constrained by morphometric analysis and radiometric chronology. Peléan domes and asymmetric domes/coulées built up the volcano, including the central edifice that hosts the youngest twin craters of Mohoş (Mohos) peat bog and lake St. Ana (Szent Anna). A comparative digital elevation model (DEM)-based morphometric analysis of lava domes (29 worldwide examples including 5 domes from Ciomadul) shows that it is the mean slope of the upper dome flank that correlates best with age. Although the logarithmic relationship is only moderately strong (R = 0.80), slope characteristics of the Ciomadul domes fit to those of 10–100 ka old domes. These young ages contradict the previous K/Ar dates giving as old as 1 Ma ages on a number of domes, but are supported by ongoing U–Pb and (U–Th)/He zircon dating. The latter methods constrain the whole volcanic activity to the past 250 ka and the emplacement of most lava domes within the period of 150–100 ka. lcanism at Ciomadul produced alternating effusive and explosive eruptions including lava dome collapses and successive crater formations. The latest, possibly subplinian explosive event formed the well-preserved St. Ana crater. Radiocarbon dating of organic remains from a sediment core that reached 11 m into the lacustrine infill of St. Ana suggests that the crater was formed prior to 26,000 years BP.