Chapter 6: Metamorphism: Modification of Rocks by Temperature and Pressure

5 Written Questions

1. a large crystal surrounded by a much finer grained matrix of other minerals in a metamorphic rock
2. the history of the changing conditions of pressure (P) and temperature (T) that occurred during metamorphism; the p-t path can be a sensitive recorder of many important factors that influence metamorphism and thus may provide insight into the plate tectonic settings responsible for metamorphism
3. metamorphism caused by high pressures and temperatures that extend over large regions, as happens where plates collide
4. mountain building, particularly by the folding and thrusting of rock layers, often with accompanying magmatic activity
5. a set of flat or wavy parallel planes produced by deformation

5 Matching Questions

1. amphibolite
2. slate
3. hornfels
4. metamorphic facies
5. migmatite

1. a groupings of metamorphic rocks of various mineral compositions formed under different grades of metamorphism from different parent rocks
2. b a granoblastic rock of uniform grain size that has undergone little or no deformation; usually formed by contact metamorphism at high temperatures
3. c a usually non-foliated metamorphic rock made up mainly of amphibole and plagioclase feldspar; foliated amphibolites can be produced by deformation
4. d a mixture of igneous and metamorphic rock produced by incomplete melting; migmatites are badly deformed and contorted, and they are penetrated by many veins, small pods, and lenses of melted rock
5. e the lowest grade of foliated rock, easily split into thin sheets; produced primarily by the metamorphism of shale

5 Multiple Choice Questions

1. metamorphism occurring at high pressure (8 to 12 kbar) and ultra-high pressure (greater than 28 kbar)
   1. low-grade (burial) metamorphism
   2. high-pressure (and ultra-high-pressure) metamorphism
   3. regional metamorphism
   4. seafloor metamorphism
2. a rock formed by the transformation of preexisting solid rocks under the influence of high pressure and temperature
   1. metamorphic rock
   2. metamorphic p-t path
   3. metamorphic facies
   4. granoblastic rock
3. a granoblastic rock produced by the low-grade metamorphism of mafic rock; chlorite accounts for the greenish cast
   1. greenstone
   2. granulite
   3. greenschist
   4. zeolite
4. a metamorphic rock that displays foliation; foliated rocks include slate, phyllite, schist, and geniess
   1. foliated rock
   2. foliation
   3. slate
   4. granoblastic rock
5. metamorphism in which buried sedimentary rocks are altered by the progressive increase in pressure exerted by overlying sediments and sedimentary rocks and by the increase in heat associated with increased depth of burial in the Earth
   1. contact metamorphism
   2. low-grade (burial) metamorphism
   3. seafloor metamorphism
   4. regional metamorphism

5 True/False Questions

1. melange → a heterogeneous mixture of rock materials produced by high-pressure, low-temperature metamorphism, found where a plate carrying a continent on its leading edge converges with a subducting oceanic plate

   True        False

2. quartzite → a very hard, white granoblastic rock derived from quartz-rich sandstones

   True        False

3. phyllite → a class of silicate minerals containing water in cavities within the crystal structure and formed by metamorphism at very low temperatures and pressures

   True        False

4. granulite → a medium- to coarse-grained granoblastic rock formed under conditions of relatively high pressure and temperature

   True        False

5. stress → the force per unit area acting on any surface within a solid body; stress consists of confining pressure and directed pressure

   True        False