GEOL 104 Lecture Notes - Lecture 17: Aureola, Mica, Metamorphic Facies

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 104
• Professor: Daniel Layton- Matthews

Document Summary

Geol104 lecture 17 subsurface processes: metamorphic rocks to time. Controlling factors in metamorphism: pressure (stress) as a metamorphic agent. Rock now has a preferred way to break. Clasts used to be round, now oblong in same direction. Layers of sand then mud, then sand, etc. Sand grains and clay minerals line up (foliation: sand grains now oblong and perpendicular to pressure. Will break along bedding plane: now folded and is another foliation, chemically active fluids. At depth, higher temps and pressures cause minerals to dehydrate. Ions are expelled with the water and can travel from to other sites in crystal structure, causing recrystallization. Fluids with different chemical makeup may change composition of surrounding host rock. Random arrangement of quartz, amphibole, biotite, and feldspar. With temp. and pressure feldspar and quartz line up and biotite and amphibole line up. Slate, phylite, schist, to gneiss = increasing temperatures and pressures. Index minerals and metamorphic grade: metamorphic grade and index minerals.