Rocks Materials of the Solid Earth Flashcards
The rock cycle is a good model for thinking about the transformation of one rock to another due to Earth processes. . Given the right conditions, any kind of rock can be transformed into any other kind of rock.
Rock Cycle
form when hot, molten rock crystallizes and solidifies
Igneous rocks
Completely or partly molten rock that is below Earth’s surface. It consists of a liquid
melt that contains gases (volatiles) such as water vapor, and it may contain solids (mineral crystals).
Magma
Completely or partly molten rock that is on the Earth’s surface
Lava
Molten rock cools and solidifies
Crystallization
When molten rock solidifies at the surface
Extrusive or Volcanic rock
Most magma loses its mobility before reaching Earth’s surface and eventually crystallizes deep below the surface.Igneous rocks that form at depth
Intrusive or Plutonic rock
If the molten material is cooled almost instantly, there is insufficient time for the ions to arrange themselves into a crystalline network. Solids produced in this manner consist of randomly distributed atoms.
Glass
Instant quenching sometimes occurs during violent volcanic eruptions that produce tiny shards of glass
Volcanic ash
Igneous rocks in which is composed almost entirely of light colored silicates such as quartz and potassium feldspar and contain about 10 percent dark silicate minerals
Granitic or Felsic
Rocks that contain at least 45 percent dark silicate minerals and calcium-rich plagioclase feldspar (but no quartz)
Basaltic or mafic
rocks with a composition between granitic and basaltic rocks and contain at least 25 percent dark silicate minerals, mainly amphibole, pyroxene, and biotite mica, with the other dominant mineral being plagioclase feldspar.
Andesitic or intermediate
Igneous rocks that has very low silica content and composed mostly of olivine minerals.
Ultramafic
the overall appearance of a rock, based on the size, shape, and arrangement of its mineral grains
Texture
Igneous rocks that form at Earth’s surface or as small intrusive masses within the upper crust, where cooling is relatively rapid. The crystals that make up fine-grained igneous rocks are so small which can be distinguished only with the aid of a polarizing microscope or other sophisticated techniques
Fine-grained texture
When large masses of magma slowly crystallize at great depth. Consist of a mass of intergrown crystals that are roughly equal in size and large enough so that the individual minerals can be identified without the aid of a microscope
Coarse-grained texture
developed when magma that has been slowly cooling and crystallising within the Earth’s crust is suddenly erupted at the surface, causing the remaining uncrystallised magma to cool rapidly.
Porphyritic texture
The large crystals in porphyritic rocks
Phenocryst
The matrix of smaller crystals wherein larger crystals are embedded.
Groundmass
Igneous rocks that have voids left by gas bubbles that escape as lava solidifies.
Vesicular texture
Nearly spherical openings as lava solidifies
Vesicles
Molten rock that is is quenched and cools quickly to become a solid.
Glassy texture
Formed from the consolidation of individual rock fragments ejected during explosive volcanic eruptions.
Pyroclastic (fragmental) texture
As magma cools, certain minerals crystallize first at relatively high temperatures. At successively lower temperatures, other minerals begin to crystallize.
Vowen’s reaction series
Occurs when the earlier formed minerals are more dense (heavier) than the liquid portion and sink toward the bottom of the magma chamber
Crystal settling
The formation of one or more secondary magmas from a single-parent magma
Magma settling
Created by accumulating existing rocks or fragments of extinct organisms on the Earth’s surface. These are compacted and cemented sediments
Sedimentary rock
indicates the nature of these rocks, for it is derived from the Latin sedimentum, which means “settling,” a reference to a solid material settling out of a fluid.
Sedimentary
Rocks are created from weathered and eroded fragments of pre-existing rock. These eroded pieces are transported, deposited, compacted, and cemented into sedimentary rocks in a process known as lithification.
Detrital sedimentary rock
sediments that originated as solid particles from weathered rocks
Detritus
Coarse (over 2mm) and rounded gravel-sized particles
Conglomerate
Coarse (over 2mm) and angular gravel-sized particles
Breccia
Medium (1/16 to 2mm) and rocks that sand-sized particles prevail
Sandstone
Medium (1/16 to 2mm) If abundant feldspar is present in the rock
Arkose
Fine (1/16 to 1/256mm) and composed mostly of clay-sized sediments intermixed with slightly larger silt-sized grains (0.0625-0.0039)
Siltstone
Very fine (less than 1/256mm) the most common sedimentary rock, is made of very fine-grained sediment and composed mainly of clay minerals
Shale/Mudstone
Form by chemical precipitation that begins when water traveling through rock dissolves some of the minerals. These minerals are carried away from their source and eventually redeposited, or precipitated, when the water evaporates away.
Chemical sedimentary rock
These rocks are formed from precipitation indirectly through life processes of water-dwelling organisms
Biochemical sedimentary rock
an abundant sedimentary rock, is composed chiefly of the mineral calcite (CaCO3).
Limestone
Starting at a microscopic scale, the calcium carbonate in the rock begins to crystallize or recrystallize into fine-grained calcite crystals. As the duration and intensity of metamorphism continues, the calcite crystals increase in size.
Crystalline limestone
Rocks that have microcrystalline calcite
Microcrystalline Limestone
A form of limestone deposited by mineral rich springs, especially hot springs, or caves. Travertine often has a fibrous or concentric banded appearance.
Travertine
a coarse rock composed of loosely cemented shells and shell fragments
Coquina
Rocks that have visible fossils in crystalline matrix
Fossiliferous Limestone
a soft, porous rock made up almost entirely of the hard parts of microscopic organisms that are no larger than the head of a pin.
Chalk
A sedimentary rock composed of microcrystalline or cryptocrystalline quartz
Chert
A chemical sedimentary rock and an example of an evaporite. Evaporation causes minerals (gypsum) to precipitate from water
Rock gypsum
A chemical sedimentary rock and an example of an evaporite. Evaporation causes minerals (salt) to precipitate from water
Rock salt
organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. It is formed when a sub bituminous coal is subjected to increased levels of organic metamorphism.
Bituminous coal
Deposits that form from the precipitation of solid mineral crystals from a concentrated solution of salt- or freshwater, in other words, from brine
evaporite deposit
As the water evaporates, dissolved materials left behind as a white crust on the ground
Salt flats
Partially altered plant material and contains less than 40 to 55 percent carbon and lots of moisture
Peat
Soft brown coal and 40 to 55 per cent carbon. Intermediate stage and moisture content is high (over 35 per cent)
Lignite
Soft black coal and 40 to 80 per cent carbon
Bituminous
Hard black coal and 80 to 95 per cent carbon
Anthracite
refers to the processes by which sediments are transformed into solid sedimentary rocks.
Lithification
As sediments accumulate through time, the weight of overlying material compresses the deeper sediments.
Compaction
The cementing materials are carried in a water-rich solution that percolates through the pore spaces between particles. Over time, the cement precipitates onto the sediment grains, fills the open spaces, and acts like a “glue” to join the particles together.
Cementation
the horizontal layers, or beds, present in most sedimentary rocks, that has certain lithologic properties
Strata (beds)
a surface that separates each layer from those above or below it.
Bedding planes
the traces or remains of prehistoric life
fossils
form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors.
Metamorphic rock
which means “to change form,” is a process that leads to changes in the mineralogy, texture (for example, grain size), and sometimes chemical composition of rocks.
Metamorhism
agents of metamorphism include heat, confining pressure, differential stress, and chemically active fluids.
Agents of metamorphism
Thermal energy (heat) is the most important factor driving metamorphism. It triggers chemical reactions that result in the recrystallization of existing minerals and the formation of new minerals. Heat sources are from nearby magma or rocks that are subjected at higher depths which has higher temperature
Heat
Pressure applied equally on all surfaces of a body and causes the spaces between mineral grains to close, producing a more compact rock that has greater density
Confining pressure
If stress is not equal from all directions and stresses are greater in one direction than in others
Differential stress
Fluids that surround mineral grains act as catalysts to promote recrystallization by enhancing ion migration.
Chemically active fluids can produce two types of metamorphism, explained below. The first type changes the arrangement and shape of mineral grains within a rock; the second type changes the rock’s chemical composition
Chemically active fluids
metamorphism takes place at low temperatures and relatively low pressure.
Low-grade metamorphism
metamorphism takes place at high temperatures and relatively high pressure.
High-grade metamorphism
Rocks experience a rise in temperature when they are intruded by magma rising from below.
Contact (thermal) metamorphism
a type of metamorphism where rock minerals and texture are changed by heat and pressure over a wide area or region.
Regional metamorphism
the range of metamorphic change a rock undergoes, progressing from low (little metamorphic change) grade to high (significant metamorphic change) grade
Degree of metamorphism
refers to any nearly flat arrangement of mineral grains or structural features within a rock.
Foliation
Rocks that do not display foliation texture and typically develop in environments where deformation is minimal and the parent rocks are composedof minerals that have a relatively simple chemical composition
Non-foliated
a very fine-grained foliated rock composed of minute mica flakes that are too small to be visible and has an excellent rock cleavage, or tendency to break into flat slabs.
Slate
Its constituent platy minerals, mainly muscovite and chlorite, are larger than those in slate but not large enough to be readily identifiable with the unaided eye. It displays glossy sheen and wavy surface.
Phyllite
are moderately to strongly foliated rocks formed by regional metamorphism. They are platy
and can be readily split into thin flakes or slabs.
Schist
the term applied to banded metamorphic rocks in which elongated and granular minerals predominate and exhibit strong segregation of light and dark silicates,
giving them a characteristic banded texture.
Gneiss
a coarse, crystalline rock whose parent rock is limestone. Composed of large interlocking calcite crystals, which form from the recrystallization of smaller grains in the parent rock.
Marble
a very hard metamorphic rock most often formed from quartz sandstone. Under moderate- to high-grade metamorphism, the quartz grains in sandstone fuse.
Quartzite
A rock granitic in composition and consist of large crystals of quartz, feldspar, and muscovite.
Pegmatite
a type of mineral deposit that consist of a localized zone of fracture-filling minerals. They typically form within fractures or fissures in rock and are often found in or near fault zones, where rocks have been fractured and deformed.
Vein deposit
ores are distributed as minute masses throughout the entire rock mass
Disseminated deposit
General term for any hydrocarbon that may be used as a fuel, including coal, oil, natural gas, bitumen from
tar sands, and shale oil.
Fossil fuel
a type of fossil fuel, formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years
coal
generated from the remains of marine plants and animals, mainly microscopic plankton, which died in ancient seas millions of years ago. With increased temperature and burial, chemical reactions gradually transform this organic matter into the liquid and gaseous hydrocarbons
OIl and Natural gas
are commonly shales and lime mudstones, which contain significant amount of organic matter. Any rock that has the capability to generate and expel enough hydrocarbons to form an accumulation of oil or gas
Source rock
A geologic environment that allows for economically significant amounts of oil and gas to accumulate underground
Oil trap
a porous, permeable layer of rock that will yield petroleum and natural gas in sufficient quantities
Reservoir rock
virtually impermeable to oil and gas and halts the upwardly mobile oil and gas and keeps the oil and gas from escaping at the surface.
Cap rock
an uparched series of sedimentary strata
Anticline
This type of trap forms when strata are displaced in such a manner as to bring a dipping reservoir rock into position opposite an impermeable bed. The upward migration of the oil and gas is halted where it encounters the fault.
Fault trap
Such areas have thick accumulations of sedimentary strata, including layers of rock
salt. Because oil and gas migrate to the highest level possible, they accumulate in the upturned sandstone beds adjacent to the salt column
Salt dome
These oil-bearing structures result primarily from the original pattern of sedimentation rather than structural deformation.
Stratigraphic (pinchout) trap
the process of injecting water, sand, and/or chemicals into a well to break up underground bedrock to free up oil or gas reserves.
Hydraulic fracturing
