GEOL 1001 Chapter : Chapter 7 Geol 1
Document Summary
Metamorphic = changed from an original parent rock protoliths. Protoliths change in texture and mineralogy due to temperature, pressure, tectonic stresses, and reactions with heated water. Unique foliation: a planar fabric from aligned minerals: these transformations can change the rock completely. Recrystallization: minerals change size and shape (without change in the identity of the mineral constituting the grains). Phase change: new minerals form with same chemical formula and different crystal structure (rearrangement of atoms)e. g. , andalusite -> kyanite. Metamorphic reaction ( neocrystallization ): new minerals with changes in temperature and pressure. Initial minerals become unstable and change to new minerals: original protolith minerals are digested in reactions, elements restructure to form new minerals. Shale transforms into a garnet mica schist this way. Minerals act like plastic, changing shape without breaking. Sources of heat: the geothermal gradient, magmatic intrusions, and compression. Shear stress- operated sideways across surface: causes material to be smeared out .
