152
bed named Sarliève tephra , but it cannot yet be linked with
any known volcano. Chronological data for Sarliève tephra
are puzzling: the TL-method has given an age of 16 ± 4 kyr
(i.e., emergence from, or fi nal part of, the last glaciation). In
a pollen sequence it is clearly situated in the Atlantic paly-
nozone (i.e., Holocene; Fourmont et al. 2006 : p. 1146, Fig. 3;
see above Fig. 8.2 ). Its position within the increase of Fagus
curve provides an approximate age of 4690 ± 40 B.P. (after
Juvigné et al. 1986 ), and necessarily more recent than
4994 ± 47 B.P. which is the age of the underlying 2 %-point
of the beginning of the continuous curve of Fagus (after
Juvigné et al. 1988a ). Mineralogical composition does not
support any correlation with the other sandy beds described
above. Otherwise, the site is far from the other three ones and
on the opposite side of the Chaîne des Puys in Limagne. The
bed of sandy volcanogenic materials is also clearly younger
than the most recent (primary) tephra found previously in
Limagne including the CF7 trachytic tephra (about 7200
B.C.), the Marsat trachytic tephra (about 7600 B.C.; Vernet
and Raynal 2000 , 2008 ), and the Pariou tephra (about 8000
B.C.; Juvigné et al. 1992 ; Vernet and Raynal 2000 ).
In all sites described above, each sandy bed corresponds
to a single local event. No similar bed has been found even in
a nearby site, so that a volcanic origin is doubtful for most of
them. The sandy beds of Fung and Espinasse were formed
during the vast deforestation of the protohistorical epoch that
has enabled increasing soil erosion by run-off and aeolian
defl ation. Hence the detrital origin of all the sandy beds is
very likely. The tephras of Beaunit and Sarliève predate the
protohistoric period of extensive deforestation in the Massif
Central. In spite of their similar age, around 5000 B.P., they
cannot be linked with any volcanic activity known in the
Massif Central. Otherwise they cannot be correlated with
one another, since neither the mineralogical composition,
nor the palynostratigraphical positions are compatible.
Hence, they cannot be defi nitively assessed as the youngest
tephras of the French Massif Central as long as similar occur-
rences are not found in nearby sites. Currently, therefore, the
eruption of Pavin volcano can be considered as the latest one
in the Massif Central.8.6 Conclusion
Pavin volcano is responsible for the most recent cataclysmic
eruptions in the Massif Central. Among various types of
activity, products of at least two Plinian columns were
injected in the high troposphere then spread northwards and
southwards by the wind. That eruption took place at
4720 ± 170 B.C., i.e. a current age of 6730 ± 170 year, and
activity occurred within a very short time range (days to
weeks). It is the fi nal one of an eruptive epoch which lasted
between 100 and 700 years after the initial Strombolian
eruption of Montcineyre volcano, followed by the phreato-
magmatic activity of the Estivadoux Maar and the
Strombolian eruption of Montchal volcano. Sandy beds
attributed as tephras in some earlier work are likely to be ero-
sion products relating to deforestation.References
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distributions (B.C.) for the
four volcanoes of the MEMP
volcanoes, computed with the
data of Table 8.1 and the
stratigraphic constraints
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E. Juvigné and D. Miallier