EAS100 Lecture Notes - Lecture 11: Extrusive Rock, Andesite, Gabbro

• School: University of Alberta
• Department: Earth and Atmospheric Sciences
• Course: EAS100
• Professor: Korhan

Document Summary

Processes of the rock cycle have built the crust. Partial melting in the asthenosphere adds material to the crust. Any molten rock that contains minerals, gasses, and rock fragments. At earth"s surface rocks begin to melt when heated to 800 c-1000 c. Greater pressures occur with depth and cause rocks to resist melting. The presence of water dramatically reduces melting temperature. Rocks are mixtures magma is often a different composition from the rock being melted. Magma is less dense than the solid rock it formed from it rises. Magma starts to push its way up pressure decreases. Process of ascent and the magma characteristics determines the eruptive style of the volcano. Oxygen: most abundant in igneous rocks amount of silica formation felsic. 50 -70 % depth in subduction zones mafic. 45 - 50 % partial melting of the mantle flow viscious moderate low ultramafic. <45 % mantle is ultramafic none in the present day relatively low temperature.