GSCI 1051 Lecture Notes - Lecture 9: Migmatite, Mica, Gneiss
Document Summary
Types of metamorphic rocks: nonfoliated- rocks lack foliation, hornfels- rocks baked by intrusions. Type varies depending on the protolith: quartzite- fused, interlocking quartz grains. Glassier than protolith sandstone: marble- interlocking calcite grains. Fossils from limestone protolith are destroyed or distorted: foliated, metaconglomerate- conglomerate with flattened clasts due to compressions, pressure solution and plastic deformation, slate- forms when shale is mildly metamorphosed strongly foliated due to realignment of clay minerals. Used for roofing due to layering: phyllite- metamorphosed slate- clay becomes fine-grained mica, making rock metallic. Mica is wavy: schist- medium to coarse grained rock with large, scaly mica flakes; foliation called schistosity . forms at higher grade than phyllite. Has metallic luster: gneiss- alternating light and dark mineral layers, known as gneissic banding, gives the rock a striped appearance. Geology 1051: migmatite- part metamorphic, part igneous; forms when felsic minerals melt and recrystallize.
