GEOL 001 Lecture Notes - Lecture 24: Sodium Oxide, Phanerite, Mica

• School: College of The Sequoias
• Department: Geology (GEOL)
• Course: GEOL 001
• Professor: Hetherington

Document Summary

Composition of melted rock determines what type of rock will be produced. Erupt, flow, or explode at the earth s surface. May have no crystals (all glass) or small + large crystals. Basalt is the archetype - composed of very fine-grained minerals (chiefly fe- and mg- rich minerals, ~50% sio2), forms mostly on the ocean floor; = 70% of all magma erupted. Volcanic rock that"s mafic moves very quickly (like liquid: felsic. + k2o, al2o3, na2o viscous (doesn"t flow as far as igneous rocks) Intrude at depths of 0. 1"s-10"s of km within the crust mm-cm scale crystals are generally evident. Can form huge masses that likely cool over a million years. Granite is the archetype - composed of k-, na- and si-rich (~70% sio2) minerals and commonly found on the continents: intermediate (andesitic) composition. Contains 55-65 wt% sio2; relative to granitic: more feo & mgo, less na2o & k2o, less volatile, less viscous.