Chapter 3 - ESC1000 Flashcards
What is the rock cycle?
A model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes.
What is magma?
Molten rock that occurs within the Earth’s crust and upper mantle.
What is lava?
It’s basically magma that reaches the surface.
What is crystallization?
When molten rock cools down and solodifies.
What is weathering?
The slow disintegration and decomposition of rocks by the daily influences of the atmosphere.
What is sediment?
Rock particles and dissolved substances resulting from weathering.
What is lithification?
When sediment that has been deposited undergoes a process that converts it into rock by cementation or compaction.
What is metamorphism?
The changes in mineral composition and texture of a rock subjected to high temperature and pressure within Earth.
Explain the rock cycle.
Melting > Magma > Lava > Crystallization > Weathering > Deposition > Lithification > Metamorphism > Melting.
What is an igneous rock?
A rock formed by the crystallization of molten magma or lava.
What are the 2 types of igneous rock?
Extrusive and Intrusive.
What are extrusive or volcanic rocks?
Igneous rock formed when lava solidifies at Earth’s surface.
What are intrusive or plutonic rocks?
Igneous rock formed when magma solidifies below Earth’s surface.
What determines the crystal’s size?
The rate of cooling.
What happens when the rate of cooling is slow?
It results in the formation of fewer, larger crystals.
What happens when the rate of cooling is fast?
It results in the formation of a solid mass of small intergrown crystals.
What are igneous rocks composed of?
Silicon and oxygen are the main components expressed as silica (SiO2) as well as Aluminum (Al), Calcium (Ca), Sodium (Na), Potassium (K), Magnesium (Mg), and Iron (Fe) make up 98% of the magma’s weight. The other 2% are trace minerals such as gold, silver, and uranium.
What are the 4 groups of igneous rocks by composition?
Granitic (Felsic), Andesitic (Intermediate), Basaltic (Mafic), and Ulatramafic.
What is granitic composition?
A compositional group of igneous rocks that indicates a rock is composed almost entirely of light colored silicates.
What is andesitic composition?
A compositional group of igneous rocks that contains at least 25% of dark silicate minerals and the other dominant mineral is plagioclase feldspar.
What is basaltic composition?
A compositional group of igneous rocks indicating that the rock contains substantial dark silicate minerals and calcium rich plagioclase feldspar.
What is ultramafic?
A compositional group of igneous rocks composed mainly of iron and magnesium rich minerals.
What is peridotite?
An igneous rock of ultramafic composition thought to be abundant in the upper mantle.
What is texture?
The size, shape and distribution of the particles that collectively constitute a rock.
What are the 6 types of texutre?
- Coarse-grained
- Fine-grained
- Porphyritic
- Glassy
- Vesicular
- Pyroclastic
What is fine-grained texture?
A texture in which crystals are too small for individual minerals to be distinguished with the unaided eye.
What is coarse-grained texture?
A texture in which crystals are roughly equal in size and large enough that individual crystals can be identified with the unaided eye.
What is porphyritic texture?
A texture consisting of large crystals (phenocrysts) embedded in a matrix of much smaller crystals groundmass).
What is vesicular texture?
A term applied to igneous rocks that contain small cavities called vesicles, which are formed when gases escape from lava.
What is glassy texture?
A term used to describe the texture of certain igneous rocks that contain no crystals.
What is pyroclastic texture?
A texture resulting from the consolidation of individual rock fragments that are ejected during a violent volcanic eruption.
What is granite?
An abundant, coarse-grained igneous rock, composed of 10-20% quartz and 50% potassium feldspar; it is used as a building material.
What is rhyolite?
The fine-grained equivalent of the igneous rock granite, composed primarily of light-colored silicates.
What is obsidian?
A volcanic glass of felsic composition.
What is pumice?
A light-colored, glassy vesicular rock commonly having granitic composition.
What is andesite?
A gray, fine-grained igneous rock and commonly exhibiting a porphyritic texture.
What is diorite?
A coarse-grained intrusive igneous rock primarily composed of plagioclase feldspar and amphibole minerals.
What is basalt?
A fine-grained igneous rock of mafic composition.
What is gabbro?
A dark-green to black intrusive igneous rock composed of dark silicate minerals.
What is the Bowen’s reaction series?
A concept proposed by N.L. Bowen that illustrates the relationships between magma and the minerals crystallizing from it during the formation of igneous rocks.
What is crystal settling?
During the crystallization of magma, the settling of the earlier-formed minerals that are denser than the liquid portion sink to the bottom of the magma chamber.
What is magmatic differentiation?
The process of generating more than one rock type from a single magma.
What are sedimentary rocks?
Rocks formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified.
What are the 4 types of sedimentary rocks?
- Detrital
- Chemical
- Biochemical
- Organic
What is a detrital sedimentary rock?
Rock formed from the accumulation of material that originated and was transported in the form of solid particles derived from both mechanical and chemical weathering.
What are the 3 types of composition in detrital sedimentary?
Gravel, sand, and silt or clay.
What is a conglomerate?
A sedimentary rock composed of gravel-size particles.
What is breccia?
A sedimentary rock composed of angular fragments that were lithified.
What is sandstone?
An abundant, durable detrital sedimentary rock primarily composed of sand-size grains.
What is shale?
The most common sedimentary rock, consisting of silt and clay size particles.
What is a chemical sedimentary rock?
Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means.
What is a biochemical sedimentary rock?
Sediment that forms when material dissolved in water is precipitated by water-dwelling organisms. Shells are common examples.
What is limestone?
A chemical sedimentary rock composed chiefly of calcite. Limestone can form by inorganic means or from biochemical processes.
What is coquina?
A coarse rock composed of loosely cemented shells and shell fragments.
What is travertine?
A form of limestone that is deposited by hot springs or as a cave deposit.
What is an evaporite deposit?
A sedimentary rock formed of material deposited from solution by evaporation of water.
What is an organic sedimentary rock?
A sedimentary rock that consists mainly of organic matter.
What is coal?
A sedimentary rock consisting of primarily organic matter, formed in stages from accumulations of large quantities of undecayed plant material.
What are the 2 processes of lithification?
Compaction and cementation.
What is compaction?
A type of lithification in which the weight of overlying material compresses more deeply buried sediment. It is most important in fine-grained sedimentary rocks such as shale.
What is cementation?
One way in which sedimentary rocks are lithified. As material precipitates from water that percolates through the sediment, open spaces are filled, and particles are joined into a solid mass.
What is strata or bed?
Parallel layers of sedimentary rock.
What are the 3 most common cement types?
Calcite, silica, and iron oxide.
What is a metamorphic rock?
Rocks formed by the alteration of preexisting rock deep within the Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids.
What are the 2 grades of metamorphism?
Low-grade metamorphism and high-grade metamorphism.
What is low-grade metamorphism?
Low temperatures and pressures change the parent rock slightly.
What is high-grade metamorphism?
High temperatures and pressures transforms the parent rock substantially.
What are the 2 settings where metamorphism occurs?
In contact metamorphism and regional metamorphism.
What is contact metamorphism?
Changes in rock caused by the heat from a nearby magma body.
What is regional metamorphism?
Is when rocks are subjected to pressures and high temperatures due to large-scale mountain building processes.
What 4 agents drive metamorphism?
Heat, confining pressure, differential stress, and chemically active fluids.
How does heat drive metamorphism?
It triggers chemical reactions that result in the recrystallization of existing minerals and the formation of new minerals.
What are the 2 sources for thermal energy (heat) in metamorphism?
- Magma intrusions.
- Depth; as the depth increases the temperature as well.
What is confining pressure?
Stress applied uniformly in all directions.
What drives confining pressure?
Depth; the more depth more pressure.
How does confining pressure drive metamorphism?
Causes the spaces between mineral grains to close, producing a more compact rock that has greater density; may cause minerals to recrystallize into new minerals that display more compact crystalline forms.
What is differential stress?
Forces that are unequal in different directions.
What happens to rocks when they are subject to differential stress in low temperatures?
The rocks are brittle and tend to fracture.
What happens to rocks when they are subject to differential stress in high temperatures?
Rocks are ductile and tend to flow rather than break forming intricate folds.
How do chemically active fluids drive metamorphism?
Fluids that surround mineral grains act as catalysts that promote crystallization by enhancing ion migration.
What are the 2 types of texture in metamorphic rocks?
Foliated and nonfoliated.
What is foliation?
A texture of metamorphic rock that gives the rock a layered appearance.
What is nonfoliated?
Describes metamorphic textures that do not exhibit foliation.
What are examples of foliated rocks?
Slate, Phyllite, Schists, and Gneiss.
What are examples of nonfoliated rocks?
Marble and Quartzite.
What are the 3 types of resources?
Metallic, nonmetallic, and energy resources.
What are pegmatites?
A very coarse-grained igneous rock commonly found as a dike associated with a large mass of plutonic rock that has smaller crystals. Crystallization in a water-rich environment is believed to be responsible for the very large crystals.
What are vein deposits?
A mineral filling a fracture or fault in a host rock. Such deposits have a sheetlike form.
What is a disseminated deposit?
Any economical mineral deposit in which the desired mineral occurs as scattered particles in the rock but in sufficient quantity to make the deposit an ore.
What are nonmetallic deposits?
A mineral resource that is not fuel and is not processed for the metals it contains.
What are the 2 groups nonmetallic deposits are divided?
Building materials and industrial minerals.
What are building materials?
A category of nonsilicate mineral resources used for building.
What are industrial minerals?
A nonmetallic mineral resource that is used in industry.
What are energy resources?
These are minerals used as resources to produce energy.
What are the 3 most common energy resources?
Coal, oil and gas.
What is a source rock?
The sedimentary rocks in which petroleum and gas originate.
What is an oil trap?
A geologic structure that allows for significant amounts of oil and gas to accumulate.
What is a reservoir rock?
The porous, permeable portion of an oil trap that yields oil and gas.
What is a cap rock?
A necessary part of an oil trap which is impermeable and hence keeps upwardly mobile oil and gas from escaping at the surface.
What are the 4 types of oil traps?
Anticline, Fault trap, Salt Dome, and Stratigraphic.
