Chapter 07 Vocab Flashcards
Compression
A push or squeezing felt by a body.
Contact Metamorphism
Metamorphism caused by heat conducted into country rock from an igneous intrusion.
Dynamic Metamorphism
Metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure.
Dynamothermal Metamorphism
Metamorphism that involves heat, pressure, and shearing.
Exhumation
The process (involving uplift and erosion) that returns deeply buried rocks to the surface.
Foliation
Layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock.
Gneiss
A compositionally banded metamorphic rock typically composed of alternating dark- and light-colored layers.
Hornfels
Rock that undergoes metamorphism simply because of a change in temperature, without being subjected to differential stress.
Marble
A metamorphic rock composed of calcite and transformed from a protolith of limestone.
Metamorphic Aureole
The region around a pluton, stretching tens to hundreds of meters out, in which heat transferred into the country rock and metamorphosed the country rock.
Metamorphic Facies
A set of metamorphic mineral assemblages indicative of metamorphism under a specific range of pressures and temperatures.
Metamorphic Foliation
A fabric defined by parallel surfaces or layers that develop in a rock as a result of metamorphism; schistocity and gneissic layering are examples.
Metamorphic Rock
Rock that forms when preexisting rock changes into new rock as a result of an increase in pressure and temperature and/or shearing under elevated temperatures; metamorphism occurs without the rock first becoming a melt or a sediment.
Metamorphic Zone
The region between two metamorphic isograds, typically named after an index mineral found within the region.
Metamorphism
The process by which one kind of rock transforms into a different kind of rock.
Metasomatism
The process by which a rock’s overall chemical composition changes during metamorphism because of reactions with hot water that bring in or remove elements.
Migmatite
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.
Mylonite
Rock formed during dynamic metamorphism and characterized by foliation that lies roughly parallel to the fault (shear zone) involved in the shearing process; mylonites have very fine grains formed by the nonbrittle subdivision of larger grains.
Phyllite
A fine-grained metamorphic rock with a foliation caused by the preferred orientation of very fine-grained mica.
Preferred Orientation
The metamorphic texture that exists where platy grains lie parallel to one another and/or elongate grains align in the same direction.
Protolith
The original rock from which a metamorphic rock formed.
Quartzite
A metamorphic rock composed of quartz and transformed from a protolith of quartz sandstone.
Regional Metamorphism
Metamorphism of a broad region, usually the result of deep burial during an orogeny.
Schist
A medium-to-coarse-grained metamorphic rock that possesses schistosity.
Shield
An older, interior region of a continent.
Shale
Fine-grained, low-grade metamorphic rock, formed by the metamorphism of shale.
Thermal Metamorphism
Metamorphism caused by heat conducted into country rock from an igneous intrusion.
