GEOL 101 Lecture 5: Geo 101 Lecture 5
Document Summary
Large continental plateaus built from basalt ows. Igneous rocks: form above and below earth"s surface, classify by mineralogy/chemistry and texture. Texture- intrusive or extrusive: intrusive form below earth"s surface, extrusive form above earth"s surface, granite= intrusive (felsic) (coarse, basalt= extrusive (ma c) ( ne) Felsic >intermediate >ma c >ultrama c: felsic+intermediate= continental crust, ma c= oceanic crust, ultrama c= mantle, ma c= fe and mg, felsic= k, na, al, si, basalt= ma c extrusive, andesite= intermediate extrusive, granite= felsic instrusive. Wednesday, january 25, 2017: often its ascent stops before it reaches the surface, pluton- general term for an intrusive body. Dike: small shallow, discordant (fracturing, often diabase (basaltic, ner grained rock. Formed at great depth, then exhumed or unroofed: stock. Extrusive- formed from cooling of lavas: crystallized from rapidly cooling magma, vesicles- once bubbles in liquid lava. Lava fountains- exsolution of gases from lava. Rhyolite ows are often ignimbrite and often welded tuffs.
