EOSC 114 Lecture Notes - Lecture 9: Gabbro, Basalt, Viscosity

• School: UBC
• Department: Earth and Ocean Sciences
• Course: EOSC 114
• Professor: Brett Gilley

Document Summary

Form where magma and gas leak out from the earth"s crust and mantle. Magma, created by melting pre-existing rock below the earth"s surface, reaches the surface through fractures and extrudes as lava or explodes as pyroclastic material. Pyroclastic material a cloud of ash that is very hot and very fast at travelling miles from volcano. Magma melted rock in the earth, below the earth"s surface. melt + crystals + bubbles. Magma density: 2. 5-3. 3 g/cm^3 (water: 1 g/cm^3) Magma viscosity: 10-10^15 pa s (water: 10^-3 pa s) Depends on temperature, gas content, crystal content. Silica (sio2) content (high silica content vs low silica content) Felsic igneous rocks: 65-75% sio2 light colour rich in k, na, al, si. Mafic igneous rocks: 45-55% sio2 rich in mg, fe. Magma temperature (600-1200 degress c) in general: Hot magma = low viscosity, low silica (mafic) Cool magma = high viscosity, high silica (felsic) Magma gas content: volatiles (dissolved gas: h2o, co2, so2)