Revised Chronology of the Youngest Volcanoes of the Chaîne Des Puys (French Massif Central)

Quaternaire, 23, (4), 2012, p. 283-290

REVISED CHRONOLOGY OF THE YOUNGEST VOLCANOES OF THE CHAÎNE DES PUYS (FRENCH MASSIF CENTRAL)

Didier MIALLIER1,6, Thierry PILLEYRE6, Serge SANZELLE6, Pierre BOIVIN2,3,4 & Philippe LANOS5

ABSTRACT

The chronology of major, young (< 15 ka) volcanoes of the central part of the Chaîne des Puys has been revised by means of tephrostratigraphy, thermoluminescence dating and radiocarbon dating. The previously assumed relative chronology between volcanoes like Pariou and Chopine was inverted; more accurate numerical ages were obtained, as exampled in the case of Côme volcano. This revision also includes previously unknown eruptions. Compilation of all available data suggests that an active volcanic period, marked by about two to three eruptions per millennium, terminated about 7 ka ago. This is an issue for interpreting the volcanism of the Chaîne des Puys during both Upper Pleistocene and Holocene. It seems to mark the end of a cycle, initiated about 80 ka ago, of feeding from a deep reservoir before magma differentiation in a system of shallow level magma chambers.

Keywords: Chaîne des Puys, volcanoes, tephrochonology, radiocarbon, thermoluminescence

RÉSUMÉ

RÉVISION DE LA CHRONOLOGIE DES VOLCANS LES PLUS JEUNES DE LA CHAÎNE DES PUYS (MASSIF CENTRAL FRANÇAIS) La chronologie relative et absolue de volcans majeurs et récents (< 15 ka) du centre de la Chaîne des Puys a été révisée par une approche téphrostratigraphique combinée à la datation par thermoluminescence et par radiocarbone. La chronologie relative précédemment admise entre certains volcans comme le Pariou et le Chopine a été inversée ; des âges plus précis ont été obtenus, par exemple pour le Côme ; enfin, la révision introduit des éruptions qui n’avaient pas encore été repérées. Le schéma chronologique permet de mettre clairement en évidence le fait qu’une période de volcanisme actif, comprenant autour de deux à trois éruptions par millénaire, s’est achevée il y a environ 7 000 ans. C’est un élément de réflexion pour l’interprétation du volcanisme pléistocène supérieur et holocène de la Chaîne des Puys. Ce volcanisme semble à la fin d’un cycle commencé il y a environ 80 000 ans par une alimentation profonde suivie par une différentiation magmatique dans un système de chambres intermédiaires.

Mots-clés : Chaîne des Puys, volcans, téphrochonologie, radiocarbone, thermoluminescence

1 - INTRODUCTION nature, presence or absence of external (i.e., non- magmatic) water and pre-existing topography (either The Chaîne des Puys is a small Quaternary volcanic volcanogenic or not). The principal volcanic types are field situated in the northern part of the continental basaltic (s.l.) scoria cones accompanied by lava flows, intraplate volcanic area of the French Massif Central basaltic or trachytic maars, as well as trachytic lava- (Boivin et al., 2009). It is basically composed of about domes and protrusions. The magma diversity resulted hundred monogenic volcanoes aligned westwards along from differentiation occurring in intermediate cham- the boundary between the Plateau des Dômes uplifted bers, where magma possibly stayed for long periods Palaeozoic block and the rift formed by the Limagne before rising up to the surface. Crustal contamination Graben (fig. 1). The volcanic centres display a variety of may also have played a role in the evolution of the types resulting from different combinations of magma magma composition (Condomines et al., 1982).

1 Clermont Université, Université d’Auvergne, LPC, CNRS/IN2P3, F-63177 AUBIERE cedex. Courriel : [email protected] 2 Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 CLERMONT-FERRAND. Courriel : P.Boivin@[email protected] 3 CNRS, UMR 6524, LMV, 5 rue Kessler, F-63038 CLERMONT-FERRAND 4 IRD, R 163, LMV, 5 rue Kessler, F-63038 CLERMONT-FERRAND 5 CNRS UMR 5060 Institut de Recherche sur les Archéomatériaux (IRAMAT), Centre de Recherche en Physique Appliquée à l’Archéologie (CRPAA), Université Bordeaux 3. Esplanade des Antilles, F-33607 PESSAC, Courriel : [email protected] 6 Clermont Université, Université Blaise Pascal, LPC, CNRS/IN2P3, F-63177 AUBIERE cedex

Manuscrit reçu le 10/09/2011, accepté le 19/06/2012

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quoted at ± 95 %. Quoting a single mean age with error limits is not exactly correct for radiocarbon because age distributions are quite complex, but this simplification gives homogeneity and clarity to the text.

2 - THE VOLCANOES AND TEPHRAS OF INTEREST

2.1 - VOLCANOES

The volcanoes of interest are succinctly presented below (details and map in Boivin et al., 2009). Puy de Côme and Puy Pariou (fig. 1) are both trachyandesitic cones accompanied by important lava flows. The construction of Puy Pariou comprised a first phreatomagmatic phase and a final strombolian phase. The first phase magma was trachyte and turned to trachyandesite in the course of eruptions, indicating the existence of a zoned reservoir (Camus, 1975; El Arabi, 1987). The eruptions were trig- gered or enhanced by interaction of magma with water, resulting in a tuff-ring and in thick distal tephra deposits characterised by phreatomagmatic features (Camus, 1975; El Arabi, 1987; Miallier et al., 2008). The cone was finally constructed by trachyandesitic strombolian projections, Fig. 1: General map of the Chaîne des Puys. For details, see Boivin while lava flows were emitted eastwards and attained the et al. (2009). Limagne plain. Puy de Dôme, the most prominent volcano Fig. 1 : Carte générale de la Chaîne des Puys. Pour les détails, voir Boivin et al. (2009). of the Chaîne des Puys, is a trachytic lava-dome of which the erection was characterised by numerous but low energetic pyroclastic flows. Puy Chopine is a rhyolithic protrusion. Its eruptions were violent and affected a large Assessing both numerical and relative chronologies area all around the volcano, eventually developing mud- of these volcanoes has been an issue for a long time flows downwards to the Limagne Graben, as far as 11 km and this chronology has been periodically revised (e.g., away from the eruption centre (Vernet et al., 2001, Vernet Juvigné & Gilot, 1986; Juvigné, 1987a, b; Juvigné et al., & Raynal, 2002). Puy Sarcoui, Aumône and Clierzou are 1988, 1992, 1994, 1996; Raynal et al., 1994; Vernet & trachytic cumulo-domes of which the growth has been Raynal, 2000; Miallier et al., 2004a, b, c). As a conti- quite calm, without significant pyroclastic flows. Vasset nuation, the present paper gives a revised chronology for and Kilian are both trachytic volcanoes of which the erup- the youngest volcanoes of the centre of the Chaîne des tions gave rise to violent pyroclastic flows initiated yb Puys, based on recent field observations and new dating phreatomagmatic eruptions. Today, they both show only results. It focuses on three major volcanoes, namely Puy small and hidden dome remains but their tephras are thick de Côme, Puy Pariou, and Puy Chopine. Other volcanoes and widespread all over the central area of the Chaîne des and tephra layers are also considered, where appropriate. Puys (Boivin et al., 2009). Thin layers of ashes attributed The approach was based on tephrostratigraphy, thermo- to either Vasset or Killian, which respective products luminescence dating (TL) and radiocarbon dating. Only still cannot be discriminated from each other (Michon, new data will be presented in detail. 1996), were observed at long distance, as far as in Swiss The present work focuses on proximal tephras, sampled lake-sediments (Martini & Duret, 1965). The Nid de la on the volcanoes themselves or in their immediate vici- Poule is a 50 m wide basaltic maar, half surrounded by nity. Actually, a substantial amount of data has already a crescent-shaped tuff ring. It is situated in the middle of been obtained from long distance airborne tephras, the still poorly understood strombolian ensemble of Petit trapped in various sediments (e.g., Reille et al., 1985; Puy de Dôme. The twin volcanoes La Vache and Lassolas, Juvigné, 1987b; Gewelt & Juvigné, 1988; Juvigné, 1991; situated at the south of the Chaîne des Puys, are trachyba- Raynal et al., 1994; Vernet & Raynal, 2000; Fourmont saltic cones that erupted simultaneously and produced a et al., 2006). However, although the latter distal deposits 16 km long lava flow. have been characterized and dated, many of them could not yet be connected to specific volcanoes. 2.2 - ORPHAN TEPHRA LAYERS In this paper, calibration of radiocarbon data was performed based on Reimer et al. (2004). Calibrated In some cases, the chronological relationship between radiocarbon and TL ages are given as elapsed time before identified tephra layers implies intermediate tephras of today (see discussion in Duller, 2011) with error limits unknown origin. Such tephras are briefly presented below.

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The Terrenoire tephra was primarily characterized 3 - TEPHROSTRATIGRAPHIC DATA 1,500 m west of the Puy de Dôme (fig. 1). It consists of poorly bedded layers of polygenic lapilli in which 3.1 - UPDATED TEPHROSTRATIGRAPHIC PATTERNS juvenile trachyandesitic lava, under the form of pumice, scoriaceous lapilli and lithics, is mixed with older In the Chaîne des Puys, it is not possible to follow conti- basaltic lava and country rocks. This tephra, which has nuously the ejecta of a volcano because the landscape is clearly a phreatomagmatic origin, is represented by thick largely covered by moors, meadows and woods. Most of units (often > 80 cm) in various places including the SE the outcrops which have provided valuable information flank of the Puy de Barme and the flanks of the poorly are distributed haphazardly by occasional excavations known trachybasaltic volcanoes Salomon and Mont- or natural accidents. Several volcanoes gave quasi-iden- chié (fig. 1). It was probably emitted by the NE crater tical pyroclastites, for example Vasset and Kilian, while of Montchié. Tephra des Chaves has been recognized in some others emitted sequentially different lavas during only one place, as a pluridecimetric unit, between Puy eruptions, such as Nugère and Pariou. These difficulties Filhu and Puy Balmet (fig. 1) (Miallier et al., 2008). induced errors and hesitations in establishing the chro- It has been deposited by surges, oriented S-N, which nology, since the pioneer works of e.g., Brousse et al. produced small U-shaped channels in the ground. Its (1970) or Camus (1975). In the present work, new field polygenic composition indicates the opening phase of observations completed by laboratory characterization a vent. Its unknown origin might be a small crater that enabled to establish localised logs (tab. 1). Cross combi- must be located in the close vicinity of the site, where nation of those logs resulted in the chronological pattern the tephra was discovered. Other orphan tephra layers presented in table 2. However, because the relative chro- are locally intercalated between the identified ones nology between certain volcanoes or tephras remains (tab. 1), without playing a role in the establishment of unknown, it is not yet possible to combine all the data in the relative chronology. a single pattern.

Assessed Coordinates chronostratigraphy X Y

Cho/Par 497518 5072259 Cho/Par 499147 5071283 Cho/Par 498134 5071987 Cho/Par 497832 5071622 Cho/Par 497824 5071544 Cha/Cho/Par/Com 495012 5070204 Cho/Sar 498565 5073255 Kil/Par 499257 5070750 Par/X3/Com 495310 5070893 Par/Com 492767 5069139 Par/Com 495119 5071443 VK/Trn/Com/AC 493912 5067851 Vas/Trn/Bar 494130 5064651 Kil/ X4/Trn 495545 5067115 VK/Trn 495214 5066501 Kil/PdD 497098 5068704 Kil/PdD 497267 5067981 Kil/PdD 496646 5068920 Kil/Pou/Par 497287 5069487 Kil/ X1/Pou/Par 497577 5069854 Par/ X2/Clz 496850 5071168 Par/ X2/Aum 496977 5070657 Par/PdD 499117 5068781 Par/PdD 501893 5070100 VaL/Vas 496700 5063572 Tab. 1: Location of the main logs used for establishing figure 1. The youngest volcano/tephra is the left one. Aum: Aumône; Bar: Puy de Barme; Com: Côme; Cho: Chopine; Cha: Les Chaves tephra; Clz: Clierzou; Kil: Kilian; Par: Pariou; Pou: La Poule; PdD: Puy de Dôme; Sar: Sarcouy; Trn; Terrenoire tephra; Vas: Vasset; VaL: la Vache & Lassolas; VK: Vasset

or Kilian (not differentiated). AC: Aumône or Clierzou (not differentiated); Xi: indicates unidentified intermediate tephra layers; X1: strombolian fall of potassic trachy-basalt; X2: fall, polygenic lapilli; X3: strombolian fall of potassic trachy-basalt; X4: trachyandesitic ashes, possibly originated from Montchié. Geographical coordinates are in the UTM (wgs84) system. Tab. 1 : Localisation des principales coupes ayant permis d’établir la figure 1. Les volcans sont indiqués par ordre stratigraphique, le plus récent étant à gauche. Aum : Aumône ; Bar : Puy de Barme ; Com : Côme ; Cho : Chopine ; Cha : téphra des Chaves ; Clz : Clierzou ; Kil : Kilian ; Par : Pariou ; Pou : La Poule ; PdD : Puy de Dôme ; Sar : Sarcouy ; Trn ; téphra de Terrenoire ; Vas : Vasset ; VaL : la Vache & Lassolas ; VK : Vasset ou Kilian (non differenciés).

AC : Aumône ou Clierzou (non différenciés) ; Xi : indiquent des téphras intermédiaires non identifiés : X1 : retombée strombolienne de trachy-basalte potassique ; X2 : retombée de lapilli polygéniques, X3 : retombée strombolienne de trachy-basalte potassique ; X4 : cendres trachyandésitiques, peut-être originaires du Montchié. Les coordonnées sont dans le système UTM (wgs84).

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Upper level Terrenoire Pariou La Poule Chopine Kilian Vasset Chaves La Vache Côme tephra tephra Lower level Terrenoire tephra + Pariou + + + + La Poule + Chopine + Vasset + Côme + + + + Puy de Dôme + + Aumône or + + Clierzou Aumône + + Clierzou + Sarcoui + Barme + + Ta b. 2: Relative chronology assessed by means of tephrostratigraphy. Sign (+) means that the products of the volcano or the tephra mentioned in the first upper horizontal line have been unambiguously observed covering the ones mentioned on the first left column, either in direct contact or with other tephra layers intercalated in between. The association “Aumône or Clierzou” means that the tephra could not be discriminated between these possible sources. Tab. 2 : Chronologie relative déduite de la téphrostratigraphie. Le signe (+) signifie que les produits du volcan ou le téphra mentionné dans la première ligne horizontale ont été observés sans ambigüité au dessus de ceux de la première colonne à gauche, soit en contact direct, soit avec un niveau inter- médiaire entre les deux. L’association « Aumône or Clierzou » signifie que la discrimination entre ces deux sources possible n’a pas pu être faite.

Recent progress in tephrostratigraphy can be illustrated of carbonized wood at 8,580 ± 350 BP (Sa 94, Deli- by the cases of Pariou and Côme. brias et al., 1964). This age was seemingly supported by the TL ages of 8.2 ± 1.6 ka (Guérin, 1983) and 8.7 3.2 - TEPHROSTRATIGRAPHY OF PUY PARIOU ± 1.8 ka (Raynal et al., 1989). But calibration of the Sa 94 radiocarbon result gives an older age of 9.6 The tephras emitted by Puy Pariou are widespread and ± 1.0 ka, also compatible with the TL ages within quite easily recognizable so that they can be considered error limits. Meanwhile, eight radiocarbon dates were as a useful chronological marker (Miallier et al., 2008). obtained for carbonized wood sampled in the Chopine Due to initial misinterpretation of field observations, Puy products and one for peat embedding the Chopine Pariou has long been considered as one of the youngest tephra (compilation in Miallier et al., 2004a). Calibra- volcanoes in the centre of the Chaîne des Puys. It is now tion and averaging of the latter dates by means of a recognized as being older than the Kilian crater as tephras Bayesian approach (see method in Lanos & Dufresne, from the latter are found at the surface of the Pariou 2012) resulted in the age of 9.66 ± 0.17 ka for Chopine, deposits and lava flows (Miallier et al., 2004a). After compatible with tephrostratigraphy and with the age of Camus (1975), it has been admitted that the Puy Chopine Puy Pariou estimated at 9.1 ± 0.8 ka (weighted mean volcano is older than the Puy Pariou, but no evidence of the three results). supporting this assumption has been presented. Recent systematic prospection allowed collecting, in various 4.2 - AGE OF PUY DE CÔME places over the Pariou lava-flows and tephras, trachytic lapilli that could be securely attributed to Chopine. Such The age of the Puy de Côme volcano was previously attribution is based on the prominent occurrence of green estimated to ca. 14-15 ka on the basis of TL measure- pyroxene and yellow sphene (Montiel, 1997; Vernet & ments (tab. 3) and field arguments (Boivin et al., 2009). Raynal, 2002). The last mineral is completely absent from This estimation is confirmed by new results. In the the trachytic nodules of Kilian and Vasset, which have Terrenoire quarry (fig. 1), the Côme deposits verlao y a the same aspect as the Chopine ones. Two first outcrops sediment of which the surface was dated by radiocarbon showing distal ashes of the Puy de Dôme covered by applied to minute carbonized plant remains, to 12,070 Pariou lapilli were meanwhile discovered (tab. 1). As a ± 220 BP (ANNUA-31428, Gif 50024), that is 14.5 ± conclusion, the Pariou eruption is now bracketed between 1.0 ka, when calibrated. In the same outcrop, the Côme both Chopine and Puy de Dôme ones. deposits were covered by the Terrenoire tephra which was dated by red TL of quartz (see method in Pilleyre et al., 1992) to 13.6 ± 1.4 ka. The Terrenoire tephra was also 4 - NUMERICAL DATING dated by red TL in the Barme quarry at 13.7 ± 1.4 ka. All ages were processed by means of a Bayesian approach 4.1 - AGE OF PUY PARIOU including radiocarbon calibration and considering strati- graphic constraints (see method in Lanos, 2004; Lanos & The assumption about the relative young age of Dufresne, 2012). The final age obtained for the Côme is Pariou was also based on a radiocarbon measurement 13.70 ± 0.88 ka.

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Stratigraphy Age Method Material Origin Laboratory Site Coordinates reference Younger 13600 TLQ Tephra Montchié Cler 437 Terrenoire 493912 5067851 than Côme ± 1400 (TR) 13700 TLQ Tephra Montchié Cler 383 Barme 494130 5064651 ± 1400 (TR) 11600 TLF lava Côme Cp 23 Pontgibault 489066 5075539 ± 1660 Côme 15900 TLF lava Côme Cp 89 Forêt de 493893 5071225 products ± 3000 Souis 12000 TLQ Tephra Côme Cler 300 Vulcania 495645 5073325 ±2000 12070 14C Carbonized ANNUA- Terrenoire 493912 5067851 ± 220 plant 31428, BP remains Gif 50024 16400 TLF lava Filhu Cp 91 Les Gardes 492123 5071150 ± 3000 or Grand Suchet Older than 17300 TLF lava Filhu Cp 92 Mazayes 489034 5070461 Côme ± 4000 or Grand Suchet 13200 TLF lava Filhu Cp 88 Bois 494034 5069570 ± 2600 or Grand d’Epinoux Suchet 13300 U/Th lava Filhu La Gardette 889620 5068857 ±3500 or Grand Suchet Tab. 3: Age results for Côme, either direct, on the Côme products, or indirect for materials older or younger than Côme. TLQ: TL for quartz grains, measured at Clermont Ferrand; TLF: TL for feldspars, measured by Guérin (1983); U/Th: U-Th method, by Condomines et al. (1982). For the site, see map on figure 1, and Boivin et al. (2009). TR refers to the Terrenoire tephra (see text). Geographical coordinates are in the UTM (wgs84) system. Tab. 3 : Résultats de datations concernant le Côme, soit directes sur les produits du Côme lui-même, soit indirectes sur des produits plus anciens (Older) ou plus récents (Younger). TLQ : TL des grains de quartz, mesurée à Clermont Ferrand ; TLF : TL des feldspaths, mesurée par Guérin (1983) ; U/Th : méthode U-Th, par Condomines et al. (1982). Pour les situations, voir la carte sur la figure 1, et Boivin et al., (2009). TR se réfère au téphra de Terre- noire (voir le texte). Les coordonnées géographiques sont dans le système UTM (wgs84).

5 - COMBINATION OF RELATIVE AND vation when the age gap is large enough compared to the NUMERICAL CHRONOLOGICAL DATA measure uncertainties. Accordingly, table 4 was derived from table 2, by combining numerical and relative chro- The numerical results may give the relative chronology nology. It is not yet possible to display all eruptions in between two volcanoes independently from field obser- a single column by lack of relative chronology between

Volcano or tephra Age (ka) References La Vache La Vache La Vache 8.66 ± 0.32 Boivin et al., 2009 Chaves 9.2 ± 1.1 Miallier et al., 2010 tephra Vasset 9.20 ± 0.36 Miallier et al., 2004-a Kilian 9.40 ± 0.20 Miallier et al., 2004-a La Poule Miallier et al., 2010 Chopine 9.66 ± 0.17 Pariou Pariou Pariou 9.1 ± 0.8 Puy de Dôme Puy de Dôme Puy de Dôme 11.04 ± 0.23 Miallier et al., 2010 Sarcoui Sarcoui 12.6 ± 1.0 Miallier et al., 2004-b Tn. tephra 13.7 ± 1.4 Côme 13.7 ± 0.9 Aumône or Clierzou Tab. 4: Chronology combining measured ages and tephrochronology. Relative chronology in a given column is assessed either by stratigraphy (tab. 2) and/or by the significant gap between measured ages. Unreferenced ages are discussed in the present paper. Uncertainties are quoted at 95 %. For Puy de Dôme, only the main phase was considered (see Miallier et al., 2010). The association “Aumône or Clierzou” means that the tephra could not be discriminated between these possible sources. For Kilian, a new radiocarbon age on carbonised wood of 8,415 ± 40 BP (Ly 15654) was combined with the four given in Miallier et al. (2004a). Tab. 4 : Chronologie combinant datations et téphrochronologie. La chronologie relative dans une colonne est déduite de la stratigraphie (tab. 2) ou d’un écart significatif dans les datations absolues. Les résultats sans référence sont discutés dans le texte. Les âges sont en années réelles, avec une incer- titude à 95 %. Pour le Puy de Dôme, seule la phase principale a été prise en compte (voir Miallier et al., 2010). L’association « Aumône or Clierzou » signifie que la discrimination n’a pas pu être faite entre les deux sources possibles. Pour le Kilian, un nouvelâge radiocarbone sur bois carbonisé de 8 415 ± 40 BP (Ly 15654) a été combiné avec les quatre donnés dans Miallier et al. (2004a).

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certain volcanoes, Vasset and Kilian for example. The Finally, one of the topics that can be addressed with tephras of these two volcanoes are too similar for being such results, i.e. looking for cycles (Nowell, 2006), distinguished in the field (Vernet & Raynal, 2002, 2008) can be illustrated by plotting the number of eruptions and their numerical ages are too close (tab. 4). Chronolo- with time. This was achieved by compiling all the gical data obtained from distal tephra deposits were not available results for the Chaîne des Puys and young considered at this stage, because, as outlined earlier, the Cézallier, a small volcanic area located 30 km south correlation is often unsecure. However, no part of the of the Chaîne des Puys (tab. 5). The test was made for interpretation of the distal observations is in contradic- the last 15 millennia only, because the lack of data for tion with the proximal ones. older periods could bias the distribution. The histogram (fig. 2) clearly evidences the termination of a period of active volcanism followed by a completely calm one. 6 - DISCUSSION AND CONCLUSION

The past experience has shown that improvement in establishing such a chronology is inherent in a process of trial and error. Among the main sources of uncertainty and error is the identification of tephra layers or even lava-flows, and their attribution to given eruptions or volcanoes. Wrong attributions induced by the similarity of tephras emitted by distinct volcanoes may result in errors in chronology. Also, the Chaîne des Puys was previously considered as a quite simple case because most of the volcanoes are monogenic. But recent observations have demonstrated that the Puy de Dôme construction was terminated by a minor summit Fig. 2: Distribution of eruptions in both Chaîne des Puys and Cézal- eruption delayed by about 2 or 3 centuries, which renders lier for about 15 ky. the Puy de Dôme chronology less simple (Miallier et al., Dark grey: assessed; light grey: to be confirmed. Data in table 5. Fig. 2 : Distribution des éruptions de la Chaîne des Puys et du Cézal- 2010), and it is now suspected that such a scenario also lier depuis environ 15 ka. En gris foncé: bien attestées; en gris-clair: occurred at Grand Sarcoui. encore énigmatiques. Données du tableau 5.

Age (ka) Eruptions Total References 5 - 4 (Fung ?) (1) Camus, 1975 6 - 5 (Sarliève ?, Beaunit ?) (2) Fourmont et al., 2006 ; Juvigné & Stach-Czerniak, 1998

7 - 6 Pavin 1 Boivin et al., 2009 8 - 7 Montchal, Montcineyre, 3 Boivin et al., 2009 Estivadoux 9 - 8 La Vache/Lassolas 1 10 - 9 Chaves, Vasset, Kilian, Poule, 5 (6) Boivin et al., 2009 Chopine (Mey) 11 - 10 Pariou, Puy de Dôme 2, (Sarcoui 2 (3) 2 ?) 12 - 11 Puy de Dôme 1 13 - 12 Sarcoui, CF2, CF3 (Barme ?) 3 (4) Vernet & Raynal, 2000 ; Guérin, 1983. 14 - 13 Nugère, Terrenoire 2 15 - 14 Côme, Tartaret 2 Miallier et al., 1994

Tab. 5: Number of eruptions per millenium in the Chaîne des Puys and Cézallier. Names and figures in brackets indicate still enigmatic results. References concern only eruptions not cited in the text. Tab. 5 : Nombre d’éruptions par millénaire dans la Chaîne des Puys et le Cézallier. Les noms et les nombres entre parenthèses indiquent des questions non complètement élucidées. Les références ne concernent que les éruptions non citées dans le texte.

It should also be outlined that several volcanoes not This is an issue for the interpretation of Upper Pleis- mentioned here certainly belong to the same period, inclu- tocene and Holocene volcanic activity in the French ding major ones like La Nugère volcano, NE of the Chaîne Massif Central. It may indicate the end of a cycle of des Puys, whose eruptive development was complex with feeding and differentiation, initiated about 80 ka ago by a chronology, around 13 ka, remaining uncertain (Vernet & ascent of primitive basalt from a deep reservoir situated Raynal, 2000; Boivin et al., 2009; Vernet & Raynal, 2012). at the base of the crust (Boivin et al., 2009).

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