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Anion
A negatively charged ion
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Aureole
The zone of metatmorphosed rock surrounding an igneous intrusion and showing the effectgs of contact metamorphism
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Bar
A unit of pressure equal to 106 dynes/cm2, approx 1 atmosphere
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Bowen's Reaction Series
The sequence of minerals that form in the process of fractional crystallization of a magma
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Bruial Metamorphism
a type of low-grade regional metamorphism affectin sediments and interlayered volcanic rock that has lower temps (200C to 450C) without any influence of orogenesis or magmatic intrusion
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Cation
A positively charged ion
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Color Index
A number that represents the percent by weight or volume of dark-colored minerals in a rock
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Contact Metamorphism
Metamorphism associated with the intrusion of an igneous mass. Relatively low pressure (<3000 bars) temps range from 200C to 1000C
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Diagenesis
The physical and chemical changes undergone by sediments when compacted and lithified
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Eugeosyncline
The oceanic part of a geosyncline characteriazed by volcanism associated with clastic sedimentatoin
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Extrusive Rocks
Igneous rocks that ahve been erupted on the surface of the earth
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Facies
A mappable, areally restrcited part of a rock body that has different fossils or lithology from other contiguous beds deposited at the same time
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Geosyncline
A major downwarp in the Earth's crust in which sediments accumulate
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Intrusive Rocks
Igneous rocks that have been formed within the Earth by emplacement of magma into pre-existing rock
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Metamorphic Facies
A set of metamorphic mineral assemblages that have reached chemical equilibrium during metamorphism within a restricted range of temperature and pressure conditions
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Metamorphic Grade
The intensity or rank of metamorphism, measured by the amount or degree of difference between the original rock and metamorphic rock
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Metasomatism
The process of mineral replacement whereby a new mineral of a different chemical composition grows in an old mineral. Interstitial liquids or gases must be present for solution and deposition to occur
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Mineral
A naturally occurring, inorganic substance, usually having an internal crystal structure
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Mineral Assemblages
The minerals that compose a rock, including the differnt kinds and their relative abundance
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Plutonic Rocks
Igneous rocks formed from a large intrusion at depth
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Provenance
The place of origin from which the constituent materals of a sedimentary rock or facies
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Regional Metamorphism
Metamorphism acting over a large areas resulting from applied pressures of 3000 to 10000 bars and temperatures of 400C to 800C.
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Regression
The withdrawal of the sea from land
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Rock Stratigraphic Unit
A rock unit that is characterized by a particular homogeneous lithology or combination of lithologies without regard to time boundaries
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Silicates
Compounds whose crystal structure contain SiO4 tetrahedra, either isolated or joined to form groups, rings, chains, sheets or three-dimensional frameworks
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Solid Solution Series
A series of minerals of identical structures that contain a mixture of 2 elements over a range of proportions
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Time Stratigraphic Unit
A rock unti that is characterized by formation during a specific period of time without regard to lithology
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Transgression
The advance of the sea onto land
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Volcanic Rocks
Igneous rocks that are generally finely crystalline or glassy, resutling from volcanic action at or near the earth's surface, either ejected explosively or extruded as lava
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Zeolites
A large group of hydoraluminosilicate minerals that are analogous in composition to the feldspars
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