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22 Cards in this Set
- Front
- Back
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What type of Rock forms when magma cools and solidifies?
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Igneous Rocks
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What forms when lava cools at the surface?
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Extrusive or Volcanic Igneous Rocks
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Magma that solidifies at depth produces __________________.
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intrusive or plutonic igneous rocks
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crystallization:
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As magma cools, the ions that compose it arrange them¬selves into orderly patterns
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Slow cooling:
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large crystals
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Rapid cooling:
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solid mass consisting of tiny intergrown crystals.
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Igneous rocks are most often classified by:
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Texture
mineral composition |
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Texture refers to:
what is the most important factor for texture? |
overall appearance of the rock based on the size and arrangement of its interlocking crystals
most important factor for texture: rate at which magma cools |
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3 Types of Texture:
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Aphanitic: grains too small to be distinguished without the aid of a microscope
Phaneritic: intergrown crystals that are roughly equal in size and large enough to be identified with the unaided eye Porphyritic: which has large crystals (phenocrysts) interbedded in a matrix of smaller crystals (groundmass); and glassy. |
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Composition of an igneous rock is due to:
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the chemical makeup of the parent magma and the environment of crystallization.
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Igneous rocks are divided into broad compositional groups based on the________________
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percentage of dark and light colored minerals they contain
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Granite and rhyolite are composed mostly of the ____________silicate minerals
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light-colored
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Mafic rocks (e.g., basalt and gabbro) are high in iron, magnesium, and calcium, low in silicon, and are _________________
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dark gray to black in color
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As magma cools those minerals with _________ melting points crystallize before minerals with _________melting points.
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higher
lower |
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crystal settling
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During the crystallization of magma, if the earlier-formed minerals are denser than the liquid portion, they will settle to the bottom of the magma chamber
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magmatic differentiation
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The process of developing more than one magma type from a common magma
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assimilation
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Once a magma body forms, its composition can change through the incorporation of foreign material, a process termed assimilation, or by magma mixing.
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Magma originates from essentially solid rock of the __________sphere
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asthenosphere
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What determines if Magma is a solid or liquid?
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rock's composition
temperature depth (confining pressure) water content |
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A _____________in pressure can cause decompression melting
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decrease
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What type of important accumulations of metals are formed by igneous processes?
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gold
silver lead copper |
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The best-known and most important ore deposits are generated from ___________________
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hydrothermal (hot-water) solutions
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