Metamorphism and metamorphic rocks tulane university. Process of mineralogical and structural textural changes of rocks in the solid state in response to physical and chemical conditions which differ from those under which they originated. Metamorphism is a process of mineral assemblage and texture variation that results from the physicalchemical changes of solid rocks, caused by factors such as crust movement, magma activity, or thermal fluid change in the earth. The relative severity of conditions that caused the metamorphism and the amount that rock changed. Hypersthene is a typical index mineral of high grade metamorphism and granulites are the common resulting metamorphic rocks. Quizlet flashcards, activities and games help you improve your grades. A more precise determination of metamorphic grade may be achieved by. Types, grade and facies of metamorphism 5btypes of. This lesson focuses on the properties of metamorphic rocks that help in its identification, most notably characteristics such as banding and foliation. Diastathermal extensional metamorphism at very low grades and.
Eighth grade lesson metamorphic rocks i betterlesson. Regional metamorphism definition is geological metamorphism involving a wide area. Clay minerals like illite, kaolinite and chlorite document processes in lowtemperature environments, such as burial diagenesis, hydrothermal alteration and lowgrade metamorphism e. Grain size reduction typically occurs in the rocks, and a range of rocks.
Low grade metamorphism takes place at temperatures between about 200 to 320oc, and relatively low pressure. Pdf very low grade metamorphism in the precuyano unit. Dislocation metamorphism is a type of metamorphism of local extent, associated with fault zones or shear zones. A model is presented in which the metamorphism develops in response to enhanced thermal gradients generated by extensional processes, and the pressure. A key to determine metamorphic grades and major isoreaction. There is also an exploration of the properties of contact metamorphism, a process of baking the rock from nearby intrusions that result in low to mid grade metamorphism. Request pdf metamorphic grade the intensity of metamorphism and the vigor of metamorphic transformation is expressed by the term metamorphic grade. Metamorphism definition of metamorphism by merriamwebster. Then he made an effort to turn the key in the lock with his mouth. Low grade metamorphic rocks are generally characterized by an abundance of hydrous minerals. The facies series concept suggests that a traverse up grade through a metamorphic terrane should follow a metamorphic field gradient, and may cross through a sequence of facies spatial sequences progressive metamorphism.
With increasing grade of metamorphism, the hydrous minerals begin to react with other minerals andor break down to less hydrous minerals. Granulite at the highest grades of metamorphism all of the hydrous. Examples of granulite facies metamorphism attributed by sandiford and powell 1 to extensional settings may represent the lower crustal analogue of the very low. Metamorphism and metamorphic rocks flashcards quizlet. The metamorphic grade is designated by 3 very general terms.
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