© Springer International Publishing Switzerland 2016 83
T. Sime-Ngando et al. (eds.), Lake Pavin, DOI 10.1007/978-3-319-39961-4_4
Volcanism of the Monts Dore
(French Massif Central)Alain Gourgaud
Abstract
Pavin volcano is located both in the southern part of Chaîne des Puys and in the Monts Dore
volcanic area. According to the very young age of Pavin volcano (about 7000 y BP), Pavin
volcanic area is considered to belong to the Chaîne des Puys, while the activity of the Monts
Dore stratovolcano ended about 200 ka ago.
The Monts Dore composite volcano (maximum elevation: 1886 m) has a surface of
500 km^2 and a volume of about 200 km^3. It is composed of two distinct volcanic
stratovolcanoes:- The Monts Dore s.s. is 3.09–1.46 Ma old. Its activity began with a caldera collapse
resulting from the eruption of a rhyolitic ash-and-pumice fl ow. In the vicinity of the
caldera, domes (and associated nuée ardente deposits) and lava fl ows were emplaced.
They are rhyolitic, trachytic, trachyandesitic, basaltic, tephritic and phonolitic in
composition. - The Sancy stratovolcano is younger, 1.1–0.23 Ma old. It is centred on a small caldera
related to a trachytic ash- and- pumice fl ow eruption, formed about 720 ka ago.
Predominant trachyandesites (75 % in volume) occur as domes, pyroclastic deposits,
lava fl ows and dykes. Basaltic lava fl ows are located on the distal part of this
volcano.
The petrology of the two volcanoes is almost identical and involves the coexistence of
two types of alkaline series, which evolved towards either silica-oversaturated (rhyolitic) or
silica-undersaturated (phonolitic) residual liquids. The main magmatic processes control-
ling this evolution are fractional crystallization, magma mixing and crustal contamination.
Pavin volcano is located within the Sancy area. Therefore, the products of the volcanic
activity of Pavin may include xenoliths derived from the Sancy volcano, e.g. trachyandesite,
basalt, trachyte, and scarce phonolite. According to its young age, Pavin is best regarded as
a satellite of the Chaîne des Puys. But the Pavin volcano was built on the south-east fl ank of
Sancy stratovolcano, which itself was located SE of the previous Monts Dore s.s. Thus, the
Pavin could also be interpreted as witnessing the fi rst activity of a future stratovolcano.
Keywords
Lake Pavin • Monts Dore • Stratovolcano • CalderaA. Gourgaud (*)
LMV, Université Clermont-Auvergne - CNRS - IRD - OPGC ,
Aubière , France
e-mail: [email protected]