GEOL 100 Lecture Notes - Lecture 11: Shock Metamorphism, Continental Crust, Protolith
Document Summary
Shock metamorphism: explosions and meteorites striking the earth"s surface. Contact metamorphism: molten material come up into existing rocks, bakes rocks around it. High-pressure metamorphism: margin where subducting plate grinds overriding plates. Burial: rocks are buried under overlying sediment. Seafloor: lots of heat and hot active fluids change rocks. Regional metamorphism: most common, affects rocks over thousands km length and 100s km width. When two pieces of continental crust slam together, fold and buckle to create mountain ranges. Entire mountain regions are composed of varying degrees of metamorphosed rock. Appalachians were as tall as the himalayas. Below surface: folding, warped rocks that are remaining roots. High degree metamorphosed rocks at surface from erosion. Fluid filled seams that crystallize into quartz. Swirled bands--metamorphosed in more than one episode. Cleavage with folds--squeezed minerals will rotate until perpendicular to stress point and bedding. Metamorphism: a change in the solid state, so there is no melting.
