Rheology of magmas Flashcards
1
Q
Controls on eruption style [3]
A
Viscosity
temp
dissolved gases
2
Q
Basalt SiO2
A
48-53 SiO2
less Viscous, Fe, Mg, high temp
3
Q
Andesite SiO2
A
52-63
4
Q
Dacite SiO2
A
63-68
5
Q
Rhyolite SiO2
A
> 68
more viscous, low Fe, Mg and temp
6
Q
Controls on viscosity
A
Network formers increase viscosity
Network breakers decrease viscosity
7
Q
Network formers [3]
A
decrease temp, increase silica, increase solid particles
= increase viscosity
8
Q
Network breakers [2]
A
cations break up tetrahedra, increase water depolymerise melt by breaking SiO2 bonds = decrease viscosity
9
Q
Pahoehoe
A
thin flows, deformable skin
