Earth Sciences 1070A/B Lecture Notes - Lecture 3: Andesite, Pumice, Gabbro

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1070A/B
• Professor: Natalie Pietrzak- Renaud

Document Summary

Molten silicate material from which igneous rock forms at high temperatures. Generated when solid rock melts, which breaks down minerals into its constitute elements. Rocks form when minerals crystalize from magma as melt begins to cool, chemistry and initial temp dictate minerals and sequence of formation. Geothermal gradient dictates that the temperature rises 30 degrees for every km of depth. Usually o(cid:272)(cid:272)urs i(cid:374) the (cid:373)a(cid:374)tle (cid:271)etwee(cid:374) 50 a(cid:374)d 250 k(cid:373) (cid:271)elow earth"s surfa(cid:272)e, where temps are over 1000 degrees. In molten magma, elements can flow freely in a disordered liquid. Increase in pressure and density in a solid tends to favor a compact crystalline structure. Increase in temperature will break down atom bonds and cause melting. Earth"s i(cid:374)terior is (cid:374)ot (cid:373)olte(cid:374) (cid:271)e(cid:272)ause of high pressure (cid:272)o(cid:373)pressi(cid:374)g it i(cid:374)to (cid:272)rystalli(cid:374)e structure even though the temp is high. If the pressure is decreased such as a fissure, solid material may melt.