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geo 101 - chapter 7

Terms in this set (30)

rock that forms when preexisting rock changes into new rock as a result of an increase in pressure & temperature &/or shearing under elevated temperatures; metamorphism occurs without the rock first becoming a melt or a sediment
metamorphic rock
the original rock from which a metamorphic rock formed
protolith
the process by which one kind of rock transforms into a different kind of rock
metamorphism
by ___, we mean that a metamorphic rock does not form by solidification of magma - rocks that do, by definition, are igneous
solid state
by ___, we mean that a metamorphic rock contains new minerals that did not occur in the protolith, &/or new texture (arrangement of mineral grains) that differs from that of the protolith
change
by ___ of environment, we mean a change in temperature or pressure, an application of ___ (a directed compression, stretching, or shear), or exposure to ___ fluids (solutions of very hot water)
modification, stress, hydrothermal
rocks undergo metamorphism when they are subjected to such ___ of metamorphism
agents
layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock
foliation
geologists use ___ to refer to the parallel surfaces or layers that can occur in a metamorphic rock
foliation
fine-grained, low-grade metamorphic rock, formed by the metamorphism of shale
slate
a fine-grained metamorphic rock with a foliation caused by the preferred orientation of very fine-grained mica
phyllite
___ forms when slate undergoes metamorphism at a temperature high enough to cause neocrystallization & the growth of white mica
phyllite
a medium-to-coarse-grained metamorphic rock that possesses schistosity
schist
___ forms at a higher temperature than does phyllite, for under hotter conditions, mica crystals can grow larger
schist
a metamorphic rock produced by metamorphism of a conglomerate; typically, it contains flattened pebbles & cobbles
metaconglomerate
a compositionally banded metamorphic rock typically composed of alternating dark- and light-colored layers
gneiss
a rock formed when gneiss is heated high enough so that it begins to partially melt, creating layers, or lenses, of new igneous rock that mix with layers of the relict gneiss
migmatite
rock that undergoes metamorphism simply because of a change in temperature, without being subjected to differential stress
hornfels
a metamorphic rock composed of quartz & transformed from a protolith of quartz sandstone
quartzite
a metamorphic rock composed of calcite & transformed from a protolith of limestone
marble
slate contains a type of foliation called ___; this allows slate to split into thin sheets
slaty cleavage
the texture of phyllite gives it a silky sheen know as ___
phyllitic luster
schist is a medium-to-coarse-grained metamorphic rock containing a type of foliation called ___
schistocity
such compositional layering, or ___, gives gneiss a striped appearance
gneissic banding
protolith of slate
shale
protolith of phyllite
slate
protolith of schist
phyllite
protolith of gneiss
schist
metamorphism caused by heat conducted into country rock from an igneous intrusion
thermal metamorphism (or contact metamorphism)
thermal (contact) metamorphism develops around an igneous intrusion, due to heat from the ___
pluton
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