Benjamin van Wyk de Vries, Michael S Petronis, Daniel Garcia

Acidic lava domes are a special monogenetic volcano type with explosive eruption hazards. Such domes raise questions about the nature of monogenetic volcanism. We study the iconic Puy de Dôme (Chaîne des Puys, Auvergne) that gave its name to dome landforms. It is asymmetric with one side more rugged and steeper than the other. Using mapping and paleomagnetism we find that it was tilted by ~20° south-westwards by bulging from a shallow intrusion, the Petit Puy de Dôme. The Puy de Dôme grew rapidly from this surface-bulging intrusion in one simple pulse, solidified, and was then tilted. During the tilting, there were landslides and the was a final small phreatomagmatic eruption. The domes history is verging on polygenetic, spanning several hundred years of intrusion and eruption, extending hazard periods. We find other uplifts with paired domes and tilted cones in the Chaîne des Puys and also others in polygenetic systems.