GEOL 2207 Lecture Notes - Andesite, Viscosity, Silicate Minerals
Document Summary
Igneous rocks form as magma cools and solidifies. Forms from partial melting of rocks inside the earth: those that crystallizes at depth are termed intrusive, or plutonic rocks (e. g. granite, magma that reaches the surface is classified as extrusive, or volcanic rocks (e. g. lava) Consists of 3 components (melts, solids, volatiles: a liquid portion (melt) that is composed of mobile ions, solid, if any, are generally silicate minerals that have already crystallised from the melt. Volatile, which are gases dissolved in the melt, including water vapour (h20), carbon dioxide (co2), and sulfur dioxide (so2) also. N2, co and h2s: has influence on impact of explosions. Vents may be yellowish because of sulphur released. Released from volcanic vents, fumaroles & geysers. Explosivity relates to viscosity (fluidity: high viscosity = low fluidity. High viscosity high gas content high explosivity. High sio2 = high viscosity high explosion. More silica, more lighter (colour wise) the rock is.
