Factor controlling metamorphism

Factor controlling metamorphism: - =============================== The main factor that control metamorphic process are; - The mineralogical composition of the parent rock. - The temperature at which metamorphism takes place. - The amount and type of pressure during metamorphism. - The type of fluid that are present during metamorphism. - The amount of time for metamorphism. • Parent rock: - ..--..--..--..--..--.. i. The parent rock or protolith is the rock that exist before metamorphism starts. ii. The important feature of protolith is it’s mineral composition and metamorphism depend on the stability of the mineral. • Temperature: - ..--..--..--..--..--..--.. i. The temperature that the rock is subjected to is a key variable in controlling the type of metamorphism. ii. All minerals are stable over a specific range of temperature. iii. Clay minerals are only stable upto about 150-200 degree celcius above that they transform into mica. iv. Other minerals are 150-1000 degree celcius. v. Some minerals crystallized into different polymorphs (same composition, different str.) e.g.: kyanite, andalusite and sillimanite are polymorphs with the composition Al2SiO5 • Pressure:- ..--..--..--..--.. i. Pressure is important in metamorphic processes for two main reason. First, it is implication for mineral stability. Second, it is implication for the texture of metamorphic rock. ii. One of the results of directed pressure and sheer stress is that rocks become foliated. iii. Rock that are subjected to very high confining pressure are typically denser than other because the mineral grains squeezed together. • Fluid; - ..--..--..-. i. Water is the main fluid present within rocks of the crust, and only that we’ll consider here. The presence of water is important for two main reason. ii. First, water facilitates the transfer of ions between minerals and within minerals, therefore increase the rate of metamorphic reaction. iii. Second, hot water can have elevated concentration of dissolved substances and therefore it is an important medium for moving certain element and continuing metamorphism. • Time: - ..--..--..— i. Most metamorphic reactions takes place at very slow rates, for example the growth of new minerals within a rock has been estimated to be 1mm per million year. ii. For this reason, it is very difficult to study metamorphic processes in lab. 👉join our group telegram https://t.me/Quartz_Academy 👉join our group Instagram https://www.instagram.com/geologyaspirant?r=nametag #factor_controlling_metamorpism #metamorphism #metamorphic_rock #geology #geology_aspirant #Owais_videos