burial metamorphism (p.250)
metamorphism due only to the consequences of very deep burial
contact metamorphism (p.250)
develops in response to heat without a change in pressure and without differential stress
differential stress (p.238)
if a material is squeezed (or stretched) unequally from different sides, we say that it is subjected to differential stress.
dynamic metamorphism (p.250)
occurs as a consequence of shearing alone under metamorphic conditions
dynamothermal metamorphism (p.252)
metamorphism with heat, compression, and shearing
exhumation (p.256)
process where deeply buried rocks end up back at the surface
gneiss (P.241)
a compositionally layered metamorphic rock, typically comprised of alternating dark-colored and light colored-layers that range in thickness from millimeters to meters.
hornfels (p. 243)
a fine-grained nonfoliated rock that contains a variety of metamorphic minerals (some equant and some inequant).
hydrothermal metamorphism (P.253)
fluid then rises through the crust, near the ridge, causing hydrothermal metamorphism of ocean-floor basalt.
index mineral (p.249)
a rock indicates the approximate metamorphic grade of the rock
metaconglomerate (p.241)
pressure and cobbles of the rock into pancake-lie shapes.
metamorphic aureole (p.250)
the distinct belt of metamorphic rock that forms around an igneous intrusion
metamorphic facies (p.248)
a set of mineral assemblages inductive of a certain range of pressure and temperature.
metamorphic foliation (p.235)
the parallel alignment of platy minerals (such as mica) and/ or the presence of alternating, light-colored and dark colored layers.
metamorphic grade (p.245)
a somewhat informal way to indicate the intensity of metamorphism, meaning the amount of degree of metamorphic change.
metamorphic mineral (p.235)
new minerals that grow in place within the solid rock only under metamorphic conditions.
metamorphic rock (p.234)
one that forms when pre-existent rock, or protolith, undergoes a solid-slate change in response to the modification of its environment at depth in earth.
metamorphic texture (p.235)
defined by the arrangement of mineral grains
metamorphic zone (p.249)
regions between isograds;
metasomatism (p.240)
hydrothermal fluids passing through a rock during metamorphism pick up ions of one element and drop off ions of another, thereby changing the overall chemical composition of the rock.
migmatite (p.242)
under certain conditions, gneiss may begin to melt, producing felsic magma and residual, still-solid mafic rock. If ther melt freezes again before flowing out of the source area, a mixture of igneous rock and relict metamorphic rock forms.
mylonite 250
is extremely fine grained and has a strong foliation that roughly parallels the fault.
241 phyllite
fined-grained metamorphic rock with a foliation caused by preferred orientation of very grained white mica
238 preferred orientation
pancake shaped grains become roughly parallel with one another, and cigar-shaped grains become aligned with one another.
234 protolith
A protolith is the original, unmetamorphosed rock from which a given metamorphic rock is formed. For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other rock and thus have a wide variety of protoliths.
244 quartzite
???
241 schist
medium to coarse grained metamorphic
257 shield
a broad region of long-lived, stable continental crust where Phanerozoic sedimentary cover either was not deposited or has been eroded away so that Precambrian rocks are exposed.
253 shock metamorphism
changes in rock due to the passage of a shock wave
241 slate
the finest grained foliated metamorphic rock
250 thermal metamorphism
local metamorphism caused by igneous intrusion
240 vein
mineral-filled cracks, commonly consist of milky-white quartz
How are metamorphic rocks different from igneous and sedimentary rocks.
metamorphism produces new minerals that did not occur in the protolith, and/or produces a new texture that is distinct from that of the protolith.
What two features characterize most metamorphic rocks?
possession of metamorphic minerals and
What is metamorphic foliation, and how does it form?
layering of metamorphic rocks. the parallel alignment of platy minerals (such as mica) and/ or the presence of alternating, light-colored and dark colored layers.
How does slate differ from a phyllite? How does phyllite differ from a schist? How does a schist differ from a gneiss?
slate/phyllite: slate is phyllite when slate is subjected to a temp high eough to poroduce a new assemblage of metamorphic minerals out of clay.
phyllite/schist: schist formed at even higher levels than phyllite.
How is hornfels nonfoliated?
it does not display a preferred orientation.
lack of foliation means either metamorphism occurred in the absence of compression and shear or that most of the new crystals are equant.
Describe the geologic settings where thermal, dynanmic, and dynamothermal metamorphism take place?
thermal: develops in response to heat without a change in pressure and without differential stress.
dynamic: shearing alone under metamorphic conditions without requiring a change in temperature or pressure.
dynamothermal: involves heat, compression and s
Why does metamorphism happen at the site of meteor impacts and along mid-ocean ridges?
Because water permeates the earth's crust and hot water chemically reacts with rock