a mylonite rock is created by what metamorphic event
Mylonite is a fine-grained, compact rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock.It is classified as a metamorphic rock.here are many different mechanisms that accommodate crystal-plastic deformation. In crustal rocks the most important processes are dislocation creep and diffusion creep. Dislocation generation acts to increase the internal energy of crystals. As the temperature and/or pressure increases on a body of rock we say the rock undergoes prograde metamorphism or that the grade of metamorphism increases. Metamorphic grade is a general term for describing the relative temperature and pressure conditions under which metamorphic rocks form.his is common in basaltic rocks that generally lack hydrous minerals. The hydrothermal metamorphism results in alteration to such Mg-Fe rich hydrous minerals as talc, chlorite, serpentine, actinolite, tremolite, zeolites, and clay minerals. Since only a small area surrounding the intrusion is heated by the magma, metamorphism is restricted to the zone surrounding the intrusion, called a metamorphic or contact aureole. Outside of the contact aureole, the rocks are not affected by the intrusive event.his is common in basaltic rocks that generally lack hydrous minerals. The hydrothermal metamorphism results in alteration to such Mg-Fe rich hydrous minerals as talc, chlorite, serpentine, actinolite, tremolite, zeolites, and clay minerals. Mylonite forms along deeply buried fault surfaces by crushing and stretching of rocks under such heat and pressure that the minerals deform in a plastic way (mylonitization).Photo Credit: Photo by Jonathan Matti, US Geological Survey.ylonite forms along deeply buried fault surfaces by crushing and stretching of rocks under such heat and pressure that the minerals deform in a plastic way (mylonitization). Photo Credit: Photo by Jonathan Matti, US Geological Survey. Alteration of the minerals, textures, and composition of a rock that is caused by exposure to severe heat, pressure, and chemical actions. Metamorphism occurs to rocks at convergent plate boundaries, rocks that have been deeply buried, and rocks that have been contacted by migrating magma or hydrothermal fluids.lteration of the minerals, textures, and composition of a rock that is caused by exposure to severe heat, pressure, and chemical actions. Metamorphism occurs to rocks at convergent plate boundaries, rocks that have been deeply buried, and rocks that have been contacted by migrating magma or hydrothermal fluids. The grade of metamorphism increases in all directions toward the intrusion. Because the temperature contrast between the surrounding rock and the intruded magma is larger at shallow levels in the crust where pressure is low, contact metamorphism is often referred to as high temperature, low pressure metamorphism.his is common in basaltic rocks that generally lack hydrous minerals. The hydrothermal metamorphism results in alteration to such Mg-Fe rich hydrous minerals as talc, chlorite, serpentine, actinolite, tremolite, zeolites, and clay minerals. Blueschist, also called glaucophane schist, is a metavolcanic rock that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to ~500 degrees Celsius.uartzite is a metamorphic rock formed when quartz-rich sandstone or chert has been exposed to high temperatures and pressures. Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. 1 Ultramylonites usually have undergone extreme grainsize reduction. 2  In structural geology, ultramylonite is a kind of mylonite defined by modal percentage of matrix grains more than 90% (Sibson, 1977). 3  Ultramylonite is often hard, dark, cherty to flinty in appearance and sometimes resemble pseudotachylite and obsidian.here are many different mechanisms that accommodate crystal-plastic deformation. In crustal rocks the most important processes are dislocation creep and diffusion creep. Dislocation generation acts to increase the internal energy of crystals. Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.uartzite is a metamorphic rock formed when quartz-rich sandstone or chert has been exposed to high temperatures and pressures. Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. Geology 200. Geology for Environmental Scientists. Major Concepts. 1  Metamorphic rocks can be formed from any rock type: igneous, sedimentary, or existing metamorphic rocks. 2  Involves recrystallization in the solid state, often with little change in overall chemical composition.3  Driving forces are changes in temperature, pressure, and pore fluids.inds of Metamorphic Rocks. 1  Slate-low grade metamorphosed shale; very fine grained; slaty cleavage should not be confused with bedding planes. 2  Phyllite-next step up from slate, larger mica grains give the rock a luster. 3  Schist-a strongly foliated rock with large grains of platy minerals.
Since only a small area surrounding the intrusion is heated by the magma, metamorphism is restricted to the zone surrounding the intrusion, called a metamorphic or contact aureole. Outside of the contact aureole, the rocks are not affected by the intrusive event