Quiz 7: Metamorphism, Metamorphic Rocks, and Hydrothermal Rocks

Metamorphic rock forms from pre-existing rock when heat and pressure cause solid-state transformations.

Metamorphism includes melting.

The original rocks must have been brittle in order for them to bend and mold under stress.

A migmatite forms when a rock partially melts.

Confining pressure is pressure applied equally on all surfaces of a substance as a result of burial or submergence.

Any new mineral that has crystallized under high-pressure conditions tends to occupy less space than did the mineral or minerals from which it formed.

Differential stress forces constituents of the rock to become parallel to one another.

Minerals that crystallize in needle-like shapes (for example hornblende) grow with their long axis parallel to the plane of foliation.

Contact metamorphism occurs adjacent to a pluton when a body of magma intrudes relatively cool country rock.

If limestone is metamorphosed at relatively low temperatures and pressures it recrystallizes into marble.

Metamorphic rocks owe their texture mostly to temperature.

Shearing causes parts of a body to move or slide relative to one another across a plane.

A metamorphic rock is similar both in mineralogy and texture to its parent rock.

Andalusite, kyanite, and sillimanite are among the best known index minerals that provide information about the temperature and pressure of metamorphism.

Schist forms at higher temperatures and pressure than slate.

Schist is a metamorphic rock characterized by a nonfoliated texture.

Gneissic texture has the minerals separated into distinct (light and dark) layers, or lenses.

Hydrothermal processes are not important along submarine mid-ocean ridges because of the cooling effect of seawater.

Meteor craters show an unusual type of metamorphism called shock metamorphism.

Hot water (or vapor) is the most important fluid involved in metamorphic processes.

___ is pressure applied equally to all surfaces of a substance as a result of burial or submergence. A) Differential stress B) Strain C) Temperature D) Confining pressure E) Magnetism

___ tends to deform objects into oblong or flattened forms. A) Differential stress B) Strain C) Temperature D) Pressure E) Magnetism

The most important factors controlling the characters of metamorphic rocks include ___. A) composition of the parent rock B) temperature C) pressure D) water E) All of the choices are correct.

The deeper a rock is below the Earth's surface ______. A) the hotter it will be B) the cooler it will be C) the cooler it will be except near a pluton or magma chamber D) has no influence on temperature

Metamorphism may involve all of the following except __. A) formation of new minerals B) changes in rock texture: grain size, grain shape, foliation, et cetera C) metasomatism D) complete melting of the rock E) recrystallization

__________ forces the constituents of a rock to become parallel to one another. A) Pressure B) Differential stress C) Strain D) Heat from a nearby pluton E) Starch

Because of the ease with which it can be split into thin flat sheets, this metamorphic rock is used for making chalkboard, pool tables, and roofs. A) granite B) marble C) gneiss D) slate E) quartzite

A _______ is characterized by parallel-orientated minerals, commonly mica. A) schist B) gneiss C) greenstone D) amphibolite E) phyllite

_____ is metamorphism coupled with the introduction of ions (charged atoms) from an external source. A) Metasomatism B) Digitization C) Intrusion D) Differentiation E) Blending

____ is the lowest-grade rock in progressive metamorphism. A) Schist B) Gneiss C) Marble D) Slate E) Phyllite

_______ metamorphism occurs adjacent to a pluton when a body of magma intrudes a relatively cool country rock. A) Sedimentary B) Igneous C) Regional D) Burial E) Contact

_____ are important economic resources for lead, zinc, gold, silver, tungsten, tin, and mercury. A) Meteor impact sites B) Hydrothermal veins C) Marble D) Schists E) Quartzites

The two most common non-foliated metamorphic rocks are _______ and marble. A) slate B) gneiss C) migmatite D) quartzite E) phyllite

_______ forms when a limestone recrystallizes during metamorphism. A) Marble B) Gneiss C) Phyllite D) Quartzite E) Coal

___ is produced when grains of quartz in sandstone are welded together when the rock is subjected to high temperatures. A) Limestone B) Marble C) Quartzite D) Monzonite E) Granite

Low grade metamorphism of _____ forms greenschist, with chlorite as the dominant mineral. A) granite B) basalt C) ocean-floor sediments D) lake sediments E) limestone

In high temperature and pressure metamorphism, if the parent rock is _____ and the dominant mineral is amphibole then the rock is amphibolite. A) granite B) basalt C) ocean-floor sediment D) lake sediment E) limestone

_______ is a very fine-grained metamorphic rock that splits easily along parallel planes. A) Slate B) Sandstone C) Marble D) Arkose E) Gneiss

___ metamorphism takes place at considerable depth underground (generally greater than 5 km). A) Contact B) Regional C) Burial D) Hydrothermal E) Shock

___ metamorphism is the term used for the process in which rocks are altered by hot water. A) Aqueous B) Tectonic C) Burial D) Hydrothermal E) Shock

Shock metamorphism can occur as a result of ______. A) volcanic eruptions B) meteor impacts C) tsunami D) earthquakes E) tornadoes

When clay minerals in a shale are subjected to elevated temperature and pressure, they may change in the solid state (that is, without melting) to form platy minerals like ___ that are at equilibrium with the new temperature/pressure conditions. A) feldspar B) amphibole C) mica D) carbonate E) pyroxene

The most important factor in controlling the final metamorphic product is __. A) temperature B) pressure/stress C) the composition of the pre-existing rock D) the effect of fluids such as water E) shock

The differential stress responsible for foliation can take place at _____. A) the Gutenberg discontinuity B) hydrothermal locations C) static plate boundaries D) ocean-ocean convergent boundaries E) the continental crust-ocean crust transition zone

A mineral is said to be ____, if after a long time it does not convert to a new mineral. A) fixed B) stable C) invariable D) crystalline E) constant

___ is a fine-grained metamorphic rock whose parent rock was basalt. A) Mica schist B) Phyllite C) Hornfels D) Garnet schist E) Gneiss

The major ____ classification of metamorphic rocks divides them into foliated and non-foliated groups. A) mineral B) genetic C) crystal size D) fabric E) textural

___ is a metamorphic rock with distinct light and dark layers that formed at high temperatures and pressures. A) Slate B) Phyllite C) Schist D) Gneiss E) Greenstone

The zone of contact metamorphism (the aureole), ____. A) extends throughout the surrounding region because rock is such a good conductor of heat B) is commonly broad, as much as several kilometers wide C) is commonly rather narrow, from 1 to 100 meters wide D) is a thin zone, less than 1 meter wide E) is a very thin zone, no more than a few centimeters in width

Metamorphic rocks are prevalent __. A) in continental crust in the middle of a plate, far away from any mountains or active faults B) within volcanoes C) in the oceanic crust away from the mid-ocean ridge D) in intensely deformed portions of large mountain ranges, where the continental crust is subjected to high temperatures, pressures, and tectonic stress E) nowhere on Earth, because regional metamorphism only occurred back when the mountains were forming

The light-color layers within a typical gneiss are formed by __. A) amphiboles B) feldspars C) pyroxenes D) olivine E) calcite

In some instances a single mineral, a ____, suffices for determination of the pressure and temperature under which a metamorphic rock formed. A) metamorphic index mineral B) metamorphic key mineral C) metamorphic trace mineral D) metamorphic mica mineral E) metamorphic pressure-temperature mineral

When a rock is buried to increasing depth it is subject to increasingly greater temperature and pressure and will undergo _____. A) contact metamorphism B) prograde metamorphism C) shock metamorphism D) retrograde metamorphism E) hydrothermal metamorphism

A migmatite is a mixed ___ rock. A) metamorphic and igneous B) metamorphic and pyroclastic C) metamorphic and sedimentary D) contact and regional metamorphic E) contact and hydrothermal metamorphic

Lines connecting points of equal temperature on maps or cross sections are called __. A) thermochrons B) isochrons C) isohyetal curves D) isopleths E) isotherms

If the mineral assemblage in metamorphic rocks is the same, they are regarded as having formed under similar pressure and temperature conditions and belong to the same _______. A) metamorphic rock group B) metamorphic mineral group C) metamorphic facies D) metamorphic temperature/pressure suite E) metamorphic province

______ stress is a type of differential stress. A) Shearing B) Confining C) Lithostatic D) Hydrostatic E) Atmospheric

_________ is the pressure felt by deeply buried rock. A) Shear pressure B) Atmospheric pressure C) Hydrostatic pressure D) Lithostatic pressure E) Differential pressure

When hot solutions emerge from the ocean floor, submarine hot springs called ________ form. A) ophiolites B) geysers C) hydrothermal vents D) mud pots E) fountains

When hot metal-rich solutions contact cold seawater at submarine spreading ridges, _______ are precipitated. A) carbonate B) ore minerals C) oils D) basalts E) silicates