Endogenous and exogenous growth of the monogenetic Lemptégy volcano, Chaîne des Puys, France

International audienceThe monogenetic Lemptégy volcano in the Chaîne des Puys (Auvergne, France) was quarried from 1946 to 2007 and offers the possibility to study scoria cone architecture and evolution. This volcano was originally 50–80 m high, but scoria excavation has resulted in a 50-m-deep hole. eginning in the 1980s, extraction was carried out with the advice of volcanologists so that Lemptégy’s shallow plumbing system and three-dimensional stratigraphy have been preserved. Detailed mapping enabled key stratigraphic units to be distinguished and the constructional phases to be reconstructed. The emplacement and evolution of the shallow plumbing system have also been unraveled. The growth of this monogeneticscoria cone included two temporally well-separated eruptions from closely spaced vents. The activity included Hawaiian, Strombolian and Vulcanian explosions, lava effusion, cryptodome and dome formation, partial collapse, satellite vent formation, eruptive pauses, and intrusion emplacement with consequent uplift. The cone shape, structure, and hence the local stress fi eld, plumbing system, and thermal state were continuously hanging,which in turn infl uenced the eruptive style and location. The plumbing system morphology and microtectonic structures both record local stress fi eld and magmatic fl ow directionchanges. Lemptégy volcano’s internal architecture,stratigraphy, and evolution show howcomplex a monogenetic volcano can be