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42 Cards in this Set
- Front
- Back
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The change (at depth) from one rock to another- due to:
Pressure Increases Temperature increase Influences by the presence of fluids Geologic Time |
Metamorphism
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Includes reactions of mineralsto changes @ depth
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Response to Equilibrium
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Metamorphism change takes place in a ____ state.
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solid
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Composition of Parent Rock
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the starting point
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Maybe confining pressure aka Lithostatic pressure
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Pressure at Depth
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-Composition of Parent Rock
-Temperature -Pressure at Depth |
Factors controlling the characteristics of Metamorphic rocks
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Geothermal gradient _____ with ____
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increases, depth
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Temperature of meta rocks may be heated by friction from
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Plate Tectonics
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Temperature of meta rocks may be cooled by
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igneous masses
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Like Bowen's Reaction Series as far as temperature...
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some minerals may melt
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= Directed Pressure
-the influence that changes texture |
Stress (the force)
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Differential Stress is
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Directed Pressure
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Differential Stress / Directed Pressure can include:
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-compressive stress
-shearing |
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equal and opposite
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compressive stress
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opposite but parallel
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shearing
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alignment of rock fabrics or minerals; in response to Directed Pressure
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Foliation
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Slaty Cleavage
Schistose Gneissic texture |
examples of foliation
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Differential Stress causes...
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Strain
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Strain results in
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Foliation
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Type of metamorphic rock formed from directed pressure of mountain building processes or other tectonism (earth movements)
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Regional
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Type of metamorphic rock formed from contact with cooling igneous masses (magma or lava)
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Contact
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Type of metamorphic rock formed in association wih hot fluids (most commonly water)
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Hydrothermal
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-hot water may carry ions from place to place
-trigger metamorphic chemical reactions |
controlling factor of fluids-hydrothermal
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can only happen in Geologic time
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time
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-Not aligned
-named on the basis of its composition -ex: quartzite and marble |
Non-foliated rock texture
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-Aligned minerals or rock fabric
-Determine type of foliation -ex: schist |
Foliated Rock texture
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Progressive Metamorphism =
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Regional
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-Progressively greater temperature and pressure
-shale (the sedimentary rock) ~Slate -> Phyllite -> Schist -> Gneiss -> Migmatite |
Progressive Metamorphism
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-Hydrothermal Minerals
-Hydrothermal Activity at Diverging Plate -Ore Deposits at Diverging Plate Boundaries -Metasomatism |
Hydrothermal Processes
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from wet to dry
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metasomatism
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In metasomatism water exchanges ions from...
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rock to rock
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minerals emplaced in cracks, joints, faults
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veins
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minerals emplaced in pores or vesicles
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disseminated
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-Ground Water
-Water Trapped in Sediments -Hydrous Minerals |
Sources of water
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like the copper ore in Michigans UP- the most economically valuable ore type
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disseminated ore deposits
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May take place at considerable depth and high temperatures
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Regional Metamorphism
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Regional Metamorphism is aka
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dynamothermal metamorpshism
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minerals include actinolite (new, asbestos min) and sodium rich plagioclase
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basalt -> greenschist
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minerals include hornblede, plagioclase feldspar, and garnet (another new mineral!)
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Basalt -> amphibole schist
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contact metamorphism is aka
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thermal metamorphism
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-Narrow zone of contact of country rock with cooling igneous mass...
-Forms a non-foliated MetaRx |
Contact Metamorphism
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Shale -> Hornfels
Limestone -> Marble Sandstone -> Quartzite (Quartz grains welded together) |
examples of nonfoliated contact MetaRx
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