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18 Cards in this Set
- Front
- Back
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metamorphic rocks |
rocks that have metamorphosed (changed) due to temp and pressure |
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two main causes of metamorphism |
heat and pressure |
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contact metamorphism |
form in shallower depths highly dependent on high temps near igneous intrusions/plutons (constact with an igneous rock intrusion) |
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regional metamorphism |
deep under the ground high temp, high pressure over broad areas |
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foliation |
observable layering - banding (high pressure - usually regional) |
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non-foliated |
no layered or banded appearance formed around igneous intrusions where temps are high but pressures are relatively low sample may possess some characteristics of the parent rock |
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slaty cleavage |
the rocks split easily along nearly flat and parallel planes, indicating that preexisting, microscopic, platy minerals were realigned during metamorphism (less than .001 mm of space between layers)
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schistosity |
visible minerals are platy or needle-shaped have grown essentially parallel to a plane due to differential stress (for coarser grained rocks - schistosity is used to describe secondary foliation) medium to large grained flakes in a preferred sheetlike orientation |
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layered or gneissic texture |
the rock became very ductile and the new minerals separated into distinct (light and dark) layers or lenses (segregation of light and dark minerals. It is indicative of high-grade metamorphism) |
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protolith |
parent rock |
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foliated texture (flaky to thick, very fine grained) composition - clay minerals, chlorite protolith - shale, tuff regional metamorphism |
Slate
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foliated texture (greater than 1mm wavy bands, fine grained) composition - micas, quartz, chlorite protolith - shale, tuff regional metamorphism |
phyllite |
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foliated (medium grained) composition - micas, quartz, garnet protolith - shale, tuff, shaly sandstone, lavas regional metamorphism |
schist |
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foliated (coarse grained) composition - quartz, micas, garnet, amphibole protolith - schist, igneous rocks regional metamorphism |
gneiss |
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non-foliated (greater than 4mm grains - breaks across grains) protolith - conglomerate regional/contact metamorphism |
metaconglomerate |
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non-foliated (about sand sized grains) protolith -sandstone regional/contact metamorphism |
quartzite |
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non-foliated (crystalline, reacts with HCl) protolith - limestone, dolomite regional/contact metamorphism |
marble |
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non-foliated (clay to silt sized grains) protolith - shale contact metamorphism |
hornfels |
