ANSC 2060 Chapter : Ch 17 Part 2
Document Summary
Metamorphic: changed from an original parent rock": parent rocks = protoliths . Metamorphic character: metamorphic rocks have distinctive properties, unique texture: intergrown and interlocking grains, unique minerals: some that are only metamorphic, unique foliation: a planar fabric from aligned minerals. Initial minerals become unstable and change to new minerals: plastic deformation: mineral grains soften and deform (elevated temperatures) Causes of metamorphism: heat (t, the upper temperature limit is melting (varies based upon rock mineral composition and water content, sources, geothermal gradient, magmatic intrusions, compression, pressure (p) Inequant grains align by rotation and new growth: compression and/or shear, hot water. Hydrothermal fluids: hot water with dissolved ions and volatiles: facilitate metamorphism, accelerate chemical reactions and alter rocks by +/- elements, metasomatism: hydrothermal alteration. Light bands of felsic minerals, dark bands of mafic minerals: migmatite -- a partially melted gneiss, 2. Ss quartzite; caco3 marble): metamorphic conditions determine the type of metamorphic rock.
