GEOL 1001 : Test 2
Document Summary
Metamorphic - changed from an original parent or protolith. Not all agents are required; they often do co-occur. Phase change - new minerals form with same chemical formula and different crystal structure. Different minerals are stable as t and p changes. Neocrystallization: initial minerals become unstable and change to new minerals. Therefore, a rock"s composition can serve as a geaothermometer or geobarometer. Pressure solution - mineral grains partially dissolve at surface contacts. Plastic deformation - mineral grains soften and deform . requires elevated temperatures. In temperature ranges between 250c and 850 c. It varies based upon rock mineral composition and water content. The geothermal gradient varies depending on tectonic setting. At active rifts . it is hotter at same depth than young mountange range or old stable continent. 3-. 4 kbars per km (surface ~ 1 bar) Metamorphism occurs mostly in 2 to 12 kbar range. Confining pressure - force applied equally in all directions.
