135
12 10 8 6 4 2 0
0
5
10
15
20
25
Ta
Th
200180 160 140120 100 80 60 40 20 005
10
15
20
25
Nb
Th
140 120 100 80 60 40 20 00
5
10
15
20
25
La
Th
14 12 10 8 6 4 2 0
0
510
15
20
25
Hf
Th
60 50 40 30 20 10 00
5
10
15
20
25
Co
Th
450 400 350 300 250 200 150 100 50 005
10
15
20
25
V
Th
CP-Bas-H
CP M-T
Clierzou
Montcineyre
Montchal-Estivadoux
Plinian Pavin
basement contaminated plinian clast
Bomb Pavin
Basement contaminated bomb
MI Puy Beaunit
Contamination trend
Fig. 7.2
Evolution of trace element compositions (ppm) of Pavin group magmas.
Black dots
:
Montcineyre basalts (lava fl
ows);
circled grey dots
: hawaïites of Montchal (lava fl
ows and scoria
fall) and Estivadoux maar (scoria fall); Pavin benmoreites:
dashed circles
(caulifl
ower bombs),
open circles
(plinian clasts).
Crosses
: basement contaminated magmas (+ bombs, × plinian
clast). Chaîne des Puys magma compositions (unpublished data): symbols as in Fig.
7.1
. Dotted
line
: possible contamination trends of Pavin clasts by xenoliths (basement xenoliths or older
basaltic fragments –unpublished data; not represented-) and emitted during the phreato-mag-matic activity
7 Magmatic Evolution of Pavin’s Group of Volcanoes: Petrology, Geochemistry...