ESC Chapter 7
Terms
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- A usually nonfoliated metamorphic rock made up mainly of amphibole and plagioclase feldspar. Foliated ones can be produced by deformation.
- Amphibolite
- A metamorphic rock formed under conditions of high pressure and moderate temperature, often containing glaucophane, a blue amphibole.
- Blueschist
- Changes in the mineralogy and texture of a rock resulting from the heat and pressure in a small area, such as the rocks near and in contact with an igneous intrusion
- Contact metamorphism
- A metamorphic rock formed under very high pressure and moderate to high temperature, typically containing minerals such as coesite (a very dense, high pressure form of quartz)
- Eclogite
- A process in which subducted metamorphic rocks rise to the surface because of buoyancy and circulation in the subduction zone
- Exhumation
- A metamorphic rock that displays foliation. Include slate, phyllitle, schist, gneiss.
- Foliated rock
- A set of flat or wavy parallel planes produced by deformation
- Foliation
- A light-colored, poorly foliated rock with coarse bands of segregated light and dark minerals throughout, produced by high-pressure, high-temperature metamorphism
- Gneiss
- A nonfoliated metamorphic rock composed mainly of crystals that grow in equant shapes, such as cubes and spheres, rather than in platy or elongate shapes. Include hornfels, quartzite, marble, greenstone, amphibolite, granulite.
- Granoblastic rock
- A medium to coarse grained granoblastic rock formed under conditions of relatively high pressure and temperature
- Granulite
- A schist containing chlorite and epidote(green) and formed by low pressure, low temperature metamorphism of mafic rocks
- Greenschist
- A granoblastic rock produced by the low grade metamorphism of mafic rock. Chlorite accounts for the greenish cast.
- Greenstone
- Metamorphism occurring at high pressure (8-12 kbar) and ultra high pressure (greater than 28 kbar)
- High Pressure and Ultra High Pressure Metamorphism
- A granoblastic rock of uniform grain size that has undergone little or no deformation. Usually formed by contact metamorphism and high temperatures.
- Hornfels
- Metamorphism in which buried sedimentary rocks are altered by the progressive increase in pressure exerted by overlying sediments and sedimentary rocks and by the increase in heat associated with increased depth in the Earth
- Low grade (burial) metamorphism
- A granoblastic rock produced by the metamorphism of limestone or dolostone
- Marble
- A heterogeneous mixture of rock materials produced by high pressure and low temperature metamorphism, found where a plate carrying a continent on its leading edge converges with a subducting oceanic plate
- Melange
- Groupings of metamorphic rocks of varyious mineral compositions formed under different grades of metamorphism from different parent rocks
- Metamorphic facies
- The history of the changing conditions of pressure and temperature that occurred during metamorphism. Can be a sensitive recorder of many important factors that influence metamorphism.
- Metamorphic P-T Path
- A rock formed by the transformatio of preexisting solid rocks under the influence of high pressure and temperature
- Metamorphic Rock
- A type of metamorphism in which a rock's bulk composition changes only because of fluid transport of chemical substances into or out of the rock
- Metasomatism
- A mixture of igneous and metamorphic rock produced by incomplete melting. Badly deformed and contorted, penetrated by many veins, small pods and lenses of melted rock.
- Migmatite
- Mountain building, particularly by the folding and thrusting of rock layers
- Orogeny
- A foliated rock that is intermediate in grade between slate and schist. Small crystals of mica and chlorite give it a glossy sheen.
- Phyllite
- A large crystal surrounded by a much finer grained matrix of other minerals in a metamorphic rock.
- Porphyroblast
- A very hard, white granoblastic rock derived from quarz rich sandstone
- Quartzite
- Metamorphism caused by high pressures and temperatures that extend over large regions, as happens where plates collide
- Regional metamorphism
- A metamorphic rock characterized by pervasive coarse, wavy foliation
- Schist
- Metamorphism associated with mid ocean ridges, in which changes in a rock's bulk chemical composition are produced by fluid transport of chemical components into or out of the rock
- Seafloor metamorphism
- Metamorphism that occurs when minerals are subjected to the high pressures and temperatures of meteorites hitting the Earth
- Shock metamorphism
- The lowest grade of foliated rock, easily split into thin sheets; produced primarily by the metamorphism of shale
- Slate
- The force per unit area acting on any surface within a solid body. Consists of confining pressure and directed pressure.
- Stress
- A class of silicate minerals containing water in cavities within the crystal structure and formed by metamorphism at very low temperatures and pressures
- Zeolite