Trachytic eruptions of the Chaine des Puys and the "man of Marsat" .

The 38th World Heritage Committee will decide soon on the registration of the Chaîne des Puys and the Limagne fault (Massif central / France) of 15 to 25 June 2014 folder.

In this context, where the Limagne is associated , research for 25 years at the foot of the volcanic area of Chaîne des Puys helped to identify four pyroclastic formations attributed to acid magma volcanoes .

The Marsat formation , identified in 1995, covers two prehistoric archaeological levels . It is related to the eruption of Puy Chopine , dated there 9479 (+ / - 49 ) years.

Massif Central - Puy des Gouttes and Puy Chopine - aerial photos paramotor / Puy de Dome, courtesy of Damien Bouyssi

The Puy des Gouttes and the Puy Chopine are associated morphologically and historically

Puy des Gouttes gets its name from the Latin gutta , meaning source ... exceptional in the Chaîne des Puys , this volcano had two sources. One located in the iron-horse, embracing the puy Chopine has long fueled a pond, called Choupina . The other to the outside Lemptéguy , was captured in the 18th century by the Benedictines of St Alyre to fuel "Fountain of the Fathers ." These sources emerge in favor of a fault line on which eight volcanoes, from Lemptéguy to Raviole . The Puy des Gouttes - 1.134 m - in the shape of a crescent open to the north , is a cinder cone with outer gentle slopes and barrancos , radial ravines and steep inner slopes. It is dated to 30,000 years and lapilli covered a large area , among which are bombs crust . A black trachybasalt flow with olivine and pyroxene phenocrysts is effused towards the west and the village of Fontêtes .

The trachytic crater of explosion of Puy Chopine notch the Puy des Gouttes .

Puy Chopine - 1.181 m - . Forming a large pyramid of trachyte , 600 m. basal diameter and 150 m. height , dominating the puy Drops of about 50 meters. Puy Chopine consists of gray trachyte with feldspar , pyroxene and black mica , but also signs of the crystalline basement - granite, diorite , corneal - who is now 200 m. above their usual level and are especially visible on the southern slope of the needle.

Its name may come from the Latin campus , referring to farmland extending at his foot and gives Campina in 1313 . Another source comes from the Gallic Suppe or Supia designating a wetland, or a lake reported in the literature between the two wells , but now its gone ... the local pronunciation gave choupina .

Puy Chopine , seen from puy des Gouttes - photo Fcarcena .

Evolution of the Gouttes-Chopine system - doc . Parc des Volcans publ . 8 / Guide volcanoes in Europe.

The history of the Gouttes-Chopine is written in two periods:

- There 30,000 years , a fissure eruption lets out a trachybasaltic casting , which flows westward and then, a series of explosions will form the cinder cone of Puy des Gouttes.

- There are about 9,500 years , an explosion crater opens and forms a trachytic maar 600 m. diameter , leaving only the southern part of Puy des Gouttes in crescent and a flap in the north. This will generate phreatomagmatic trachytic clouds which will cover more than 20 km ² ... the Gouttes cone is buried under deposits of clouds which descend to share its outer flanks and will dig gullies that give the characteristic appearance. At the end of the eruptive cycle , granitic basement panels slide into the crater. Degassed magma will rise like a piston in the chemney, pushing back the products that clog to build the needle of Puy Chopine ( in a similar pattern to the needle of Mount Pelee ) . The main slab of granite is 150 m. long, 100 m. wide and high ... imagine the force to lift the mass . A fumerolienne activity will close the eruptive cycle.

The Puy Chopine notching the puy des Gouttes - Winter picture / aerial photos paramotor / Puy de Dome, courtesy of Damien Bouyssi .

The history of the "man of Marsat" :

at the edge of the Mirabel strem in the Limagne fault, a hunter-gatherer camp is held in the spring / early summer.

After a rain of ashes, despite the distance, due to the collapse of the eruptive column in the Pelean phase of the eruption of Puy Chopine, a mudslide will invade the camp. The water accumulated in various dams will take rocky debris, blocks of trachyte, mixed with tree trunks, forming a destructive lahar. After the lahar, the valley is covered by a thin layer of trachyte ash.

This is the first time we watch that a Mesolithic hunting camp was a direct witness an eruption of the volcanos, though placed at considerable distance - more than 11 km - from the eruptive source.

Sources :

- Eruptions trachytiques de la Chaîne des Puys (France) et leurs impacts sur les environnements - par Gérard Vernet et Jean-Paul Raynal - link

- Domenicus malleotus - le Puy Chopine - link

- Volcan Terre d'éveil - link

- Guide des volcans d'Europe et des Canaries - M.Krafft & de Larouzière - éd. Delachaux & Niestlé

- Chaîne des Puys - le Puy Chopine - l'aiguille de protusion par B.Dichamp - link

- Les photos aériennes du Puy de Dôme - merci à Damien Bouyssi pour son autorisation de diffusion -   link