chapter 7 metamorphism Flashcards
Thus, every metamorphic rock has a ______ —the rock from which it was formed
parent rock
_______________, which means to “change form,”
Metamorphism
Subducting sediments are metamorphosed due to __________________
increase in pressure and temperature
Shallow crustal rocks are metamorphosed by ____________
heat from rising magma
Deeply buried sedimentary strata are metamorphosed
burial metamorphism
forces that deform rock that are unequal in different directions and are referred to as ______________
differential stress
Pressure, like temperature, also increases with depth as the thickness of the overlying rock increases. Buried rocks are subjected to ____________, which is analogous to water pressure, in which the forces
are applied equally in all directions
confining pressure
When substantial chemical change accompanies metamorphism the process is called _____________
metasomatism
Recall that the term _______ is used to describe the size, shape, and arrangement of grains within a rock
texture
The term _________ refers to any planar (nearly flat) arrangement of mineral grains or structural features within a rock
foliation
__________ textures develop in a wide range of rock types and metamorphic environments when minerals in the parent rock recrystallize to form new minerals.
Porphyroblastic
Notice that the dark biotite crystals and light silicate minerals (quartz and feldspar) have separated, giving the rock a banded appearance called ________ texture.
gneissic
Under higher temperature- pressure regimes, the minute mica and chlorite crystals in slate begin to grow. When these platy minerals are large enough to be discernible with the unaided eye and exhibit a planar or layered structure, the rock is said to exhibit a type of foliation called ________
schistosity
_______ no preferred directional texture
non-foliated texture
Foliation can form in various ways, including:
-Rotation of platy and/or elongated minerals
-Recrystallization of minerals in the direction of preferred orientation
-Changing the shape of equidimensional grains into flattened or elongated shapes with preferred orientation
_______ is a very fine-grained (less than 0.5 millimeter) foliated rock composed of minute mica flakes
that are too small to be visible
Slate
________ represents a gradation in the degree of metamorphism between slate and schist. Its constituent platy minerals are
larger than those in slate but not yet large enough to be readily identifiable with the unaided eye
Phyllite
________ is a coarse, crystalline metamor-
phic rock whose parent was limestone or dolostone
Marble
_______ is a very hard metamorphic rock formed from sandstone , Under moderate- to high-grade metamorphism, the grains in sandstone fuse together.
Quartzite
______________ occurs when rocks immediately surrounding a molten igneous body are “baked
Contact or thermal metamorphism
When hot, ion-rich fluids circulate through fissures and cracks in rock, a chemical alteration called _________ occurs
hydrothermal metamorphism
When the host rock is highly fractured, mineral matter contained in these _________ may precipitate to form a variety of minerals, some of which are economically important
hydrothermal solutions
Most metamorphic rock is produced by ______________ during mountain building when large segments of Earth’s crust are intensely deformed along convergent plate boundaries
regional metamorphism
Rocks and sediments can also be car- ried to great depths along convergent boundaries where oceanic lithosphere is being subducted. This phenomenon, called _________________, differs from burial metamorphism in that differential stresses play a major role in deforming rock as it is metamorphosed.
subduction zone metamorphism
