13. Kao
Fuji
Mayan

16. Bali

18. Pinatoubo

21. Pinatoubo

23. Caldera collapse
“normal faults”

24. Stages of the
Yellowstone
Caldera
‘resurgent
caldera”

25. Cinder Cones
Stratovolcanoes
Gas
Content
Fountains: shields and
plateaus
Domes
Viscosity

29. Classification of Igneous Rocks
Figure 2-5. Classification of the pyroclastic rocks. a. Based on type of material. After Pettijohn (1975) Sedimentary Rocks, Harper & Row, and Schmid (1981) Geology, 9, b. Based on the size of the material. After Fisher (1966) Earth Sci. Rev., 1,

32. FeO , MgO, CaO
Wt. %
oxides
Na2O, K2O
H2O
Wt. % SiO2

33. Water Saturation
Exsolution of
a vapor
Water
content
(wt. %)
of a
magma
Basalt Andesite Rhyolite
Composition

34. Fractional Crystallization
Basalt Andesite Rhyolite
low H2O Explosive volcanism ?
50 % SiO % SiO2
Water content of a rhyolitic magma ????

38. Mt. St. Helens

39. Granites

42. Origin of Andesites Fractional crystallization of basaltic magma
Contamination of basaltic magma by continental crust
Both of the above
Partial melting of “special (wet ?) mantle”

44. Origin of Granite/ Rhyolite
Fractional crystallization of basaltic magma ( volume problem for some areas)
Partial melting of continental crust