3 main categories of rocks Flashcards
Forms when magma or lava cool to solid form, either glass or masses of tightly intergrown mineral crystals
Igneous Rocks
Completely or partly molten rocks inside the earth’s crust
Magma
solid – _____________
melt – ions
volatiles – vapors
silicate minerals
solid – silicate minerals
melt – __________
volatiles – vapors
ions
solid – silicate minerals
melt – ions
__________ – vapors
volatiles
Magma that reached the surface
Lava
Crystals are large if they had a long time to grow in a _____________.
slowly cooling magma
Crystals are small if they formed quickly in _____________.
rapidly
cooling lava
Formed from magma and tends to take a long time to solidify into rock
Intrusive or Plutonic
Igneous rock that has phaneritic texture
Intrusive or Plutonic
Formed from lava
and tends to solidify quickly
Extrusive or Volcanic
Igneous rock whose common
textures include aphanitic and porphyritic
Extrusive or Volcanic
granitic: >65% silica, generally
light-colored
Felsic
andesitic: 55-65% silica,
generally medium colored (medium gray)
Intermediate
basaltic: 45-55% silica, usually
dark colored
Mafic
<45% silica, generally very
dark colored
Ultramafic
The overall appearance of rock based on size, shape, and crystal arrangement
Texture
Factors affecting the texture of Igneous rocks:
1. Rate of cooling
2. Amount of Silica
3. Amount of __________
Volatiles
Rocks that have large crystals embedded in a matrix of smaller crystals
Porphyritic
Large crystals in Phorphyritic rocks
Phenocrysts
The matrix of smaller crystals in Phorphyritic rocks
Groundmass
Texture that is produced when magma cools slowly at depth
Phaneritic (course-grained)
Texture of a rock that consists of a mass of intergrown crystals that are roughly equal in size and are large enough so that it can be identified without an aid of a microscope
Phaneritic (course-grained)
Texture that is produced when lava cooled quickly on or near the Earth’s surface
Aphanitic (fine-grained)
Aphanitic
a = not
phaner = __________
visible
Crystals that are so small that they can only be distinguished through the use of microscope
Aphanitic (fine-grained)
Texture of a rock produced by slow then rapid cooling
Porphyritic
Texture of a rock produced by very rapid cooling
Glassy
Texture of a rock produced from the debris of an explosive eruption
Pyroclastic
Texture of a rock with air bubbles trapped inside
Vesicular
Texture of a rock with unusual large crystals
Pegmatitic
Category of rock that formed at or near the surface of the Earth
Sedimentary Rocks
Formed when mineral crystals and clasts of plants, animals, or rocks are compressed or naturally cemented together.
Sedimentary Rocks
The process of breaking down or
dissolving rocks
Weathering
The process by which the soil and rock particles are driven by a transport agent
Erosion
The laying down of sediment carried by any transport agent
Deposition
The process wherein the sediments are turned into sedimentary rocks.
Lithification
Sedimentary rocks formed from the eroded parts of other rocks
Clastic
Components of Clastic rocks
grains, matrix, cement
Grains, matrix and cement are the
components of __________ rocks.
Clastic
Sedimentary rocks formed from the accumulation of materials that originated and is transported as solid particles derived from both chemical and mechanical weathering
Detrital
Sedimentary rocks that form via evaporation and precipitation from solution or lithification of organic matter
Non-Clastic
Classified as evaporites (halite, gypsum, and dolostone), precipitates (limestone), and bioclastics (coal, coquina)
Non-Clastic Sedimentary Rocks
Sedimentary rock that forms when a soluble material produced by chemical weathering are precipitated by either organic or inorganic processes
Chemical
Sedimentary rock that forms from the accumulation and lithification of organic debris, such as leaves, roots, and other plant or animal material
Organic
_____________, which means to “change form,” is a process that leads to changes in the mineral content, texture, and sometimes the chemical composition of rocks.
Metamorphism
Takes place where preexisting rock is
subjected to new conditions, usually elevated temperatures and pressures, that are significantly different from those in which it initially formed
Metamorphism
The most important factor driving metamorphism
Heat
Provides the energy needed to drive the chemical reactions that result in the recrystallization of existing minerals and/or the formation of new minerals
Heat
Like temperature, it also increases with depth as the thickness of the overlying rock increases
Pressure
Mostly, the fluid is water that contains ions in the solution, thus hydrating the minerals during the process
Chemically Active Fluids
2 Textures of Metamorphic Rocks
Foliated and Nonfoliated
The term foliation refers to any planar (nearly flat) arrangement of mineral grains or structural features within a rock.
Foliated Texture
The term __________ refers to any planar (nearly flat) arrangement of mineral grains or structural features within a rock.
foliation
Typically develop environments where deformation is minimal and the parent rocks are composed of minerals that exhibit equidimensional crystals, such as quartz or calcite
Nonfoliated Texture
Type of Metamorphism that has heat and reactive fluids as main factors
Contact Metamorphism
Occurs when a pre-existing rock gets in contact with magma
Contact Metamorphism
Create nonfoliated metamorphic rocks
Contact Metamorphism
Type of Metamorphism that has pressure as main factor
Regional Metamorphism
Occurs in areas that have undergone considerable amount of mechanical deformation and chemic recrystallization during orogenic event which are commonly associated with mountain belts
Regional Metamorphism
Type of Metamorphism that occurs in a regional/large scale
Regional Metamorphism
Create foliated metamorphic rocks
Regional Metamorphism
Rocks that are altered at high temperatures and moderate pressures by hydrothermal fluids
Hydrothermal Metamorphism
Type of Metamorphism that is common in basaltic rocks that generally lack hydrous minerals
Hydrothermal Metamorphism
When an extraterrestrial body, such as meteorite or comet impacts with the Earth or if there is a very large volcanic explosion, ultrahigh pressures can be generated in the impacted rock.
Shock Metamorphism
These ultrahigh pressures can produce minerals that are only stable at very high pressure, such as the SiO2 polymorphs coesite and stishovite.
Shock Metamorphism
They can produce textures known as shock lamellae in mineral grains, and such textures shatter cones in the impacted rock.
Shock Metamorphism
