Erth201

yas

3 ways to melt a rock

Increase temp, dec pressure, increase volatile contents

volatile contents?

readily vaporized

what kind of rock forms from felsic magma cooled in a large pluton at depth?

granite

When magma stalls in crust and crystallizes, some crystals settle to the bottom of chamber. THis generally leads to?

residual melts becoming more silica rich (more felsic)

Important volatiles in magma?

water and co2

generally when a rock is partially melted, the chemistry of the melt is what compared to the original chemistry

more felsic

if a body of magma becomes more felsic, its viscosity will?

increase

high viscosity?

thick

compared to coarse grained igneous rocks, fine grained cool and solidify?

cool and solody more quickly

Vesicles in an igneous rock are evidence for which of the following?

degassing of volatiles

what kind of rock is felsic?

igneous

felsic rock silica composition

high

felsic rock elements?

feldspar and quartz

mafic elements

magnesium and iron

mafic rock type?

igneous

Intrusive igneous rocks cool?

below ground

extrusive igneous rocks cool?

on earths surface

3 types of earthquakes in cascadia?

subduction zone, deep, shallow

Term

Definition

Intrusive Igneous Rocks

"Igneous rocks that crystallize below ground from magma."

Extrusive Igneous Rocks

"Igneous rocks that crystallize on Earth's surface from lava."

Magma

"A mixture of melt

Lava

"Magma that reaches the Earth's surface."

Decompression Melting

"Melting of rock that occurs when the pressure on the rock is reduced

Flux Melting

"Melting of rock that occurs due to the addition of volatiles (like water)

Volatiles

"Substances that evaporate easily (e.g.

Heat-Transfer Melting

"Melting that occurs when heat is transported into cooler shallow crust by migrating magma

Felsic (Silicic) Magma

"Magma with a high silica content

Intermediate Magma

"Magma with a silica content between felsic and mafic

Mafic Magma

"Magma with a relatively low silica content

Ultramafic Magma

"Magma with a very low silica content

Partial Melting

"The process by which only some parts of a rock melt; the resulting magma is typically more felsic than the source rock because silica enters the liquid more readily."

Assimilation

"The process by which magma incorporates surrounding wall rock

Magma Mixing

"The process where magmas from different sources enter the same magma chamber and mix

Fractional Crystallization

"The sequential formation and settling of crystals from a cooling magma

Bowen's Reaction Series

"A schematic description of the order in which different minerals crystallize from a cooling magma. It includes a discontinuous series (olivine

Viscosity

"A measure of a fluid's resistance to flow. Magma viscosity depends on silica content (lower $SiO_2$ = lower viscosity)

Dike

"A tabular igneous intrusion that cuts across pre-existing layers or rock structures."

Sill

"A tabular igneous intrusion that forms parallel to pre-existing layers in country rock."

Pluton

"A blob-shaped igneous intrusion that ranges in size from tens of meters to tens of kilometers."

Batholith

"A very large intrusive igneous body

Stoping

"A process by which magma rises by dislodging and assimilating blocks of overlying country rock."

Xenolith

"A piece of country rock (wall rock) that has fallen into a magma body but has not completely melted

Crystalline Texture

"An igneous rock texture composed of interlocking crystals. Subdivided into phaneritic (coarse-grained

Porphyritic Texture

"An igneous rock texture characterized by larger crystals (phenocrysts) embedded in a finer-grained matrix (groundmass)

Fragmental Igneous Rocks

"Igneous rocks formed from fragments of volcanic debris

Glassy Igneous Rocks

"Igneous rocks with a glass-like texture due to very rapid cooling

Weathering

"The combination of processes that break up and corrode solid rock

Jointing

"Natural cracks in rocks

Frost Wedging

"Physical weathering process where water freezes in rock cracks

Root Wedging

"Physical weathering process where plant roots grow into cracks in rocks and exert pressure

Exfoliation

"A type of physical weathering where curved sheets of rock are stripped from a larger rock mass

Dissolution

"A chemical weathering process where minerals dissolve in water

Hydrolysis

"A chemical weathering process where water reacts with minerals to form new minerals (e.g.

Erosion

"The separation and removal of detritus (weathered rock material) from its original substrate by agents like wind

Transportation

"The movement of eroded clasts (sediment particles) away from their original locations by wind

Deposition

"The process by which sediment settles out of the transporting medium (wind

Lithification

"The transformation of loose sediment (detritus) into solid rock

Clastic Sedimentary Rocks

"Sedimentary rocks composed of cemented-together fragments (clasts or detritus) of pre-existing rocks and minerals."

Biochemical Sedimentary Rocks

"Sedimentary rocks formed from the shells or skeletons of organisms (e.g.

Organic Sedimentary Rocks

"Sedimentary rocks formed from carbon-rich relicts of plants or other organisms (e.g.

Chemical Sedimentary Rocks

"Sedimentary rocks formed by the precipitation of minerals directly from surface water solutions (e.g.

Clast/Grain Size

"The diameter of the individual fragments or grains in a clastic sedimentary rock. Categories include boulders (>256mm)

Angularity/Sphericity

"Terms describing the shape of clasts. Angularity refers to the sharpness of edges and corners

Sorting (Sediment)

"The uniformity of grain size in a sedimentary rock. Well-sorted sediments have grains of similar size; poorly-sorted sediments have a wide variety of grain sizes."

Sediment Maturity

"The degree to which a sediment has evolved from its source

Conglomerate

"A coarse-grained clastic sedimentary rock composed of rounded pebbles and cobbles (>2mm)."

Breccia

"A coarse-grained clastic sedimentary rock composed of angular clasts (>2mm)."

Sandstone

"A medium-grained clastic sedimentary rock composed of sand-sized grains (0.06-2mm). Varieties include quartz sandstone

Shale

"A very fine-grained clastic sedimentary rock composed of clay and/or very fine silt (<0.004mm) that breaks into platy sheets."

Mudstone

"A very fine-grained clastic sedimentary rock composed of clay and/or very fine silt (<0.004mm) that does not break into platy sheets."

Limestone

"A biochemical or chemical sedimentary rock primarily composed of calcium carbonate ($CaCO_3$)

Chert

"A microcrystalline or cryptocrystalline sedimentary rock material composed of silicon dioxide ($SiO_2$). Can be biochemical (from silica shells of organisms like radiolarians) or chemical (replacement chert)."

Coal

"An organic sedimentary rock formed from the accumulation and alteration of plant remains in swampy environments."

Oil Shale

"An organic sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil can be produced."

Travertine

"A form of limestone (a chemical sedimentary rock) deposited by mineral springs

Evaporites

"Chemical sedimentary rocks formed by the precipitation of minerals from saline water as it evaporates. Examples include gypsum and halite (rock salt)."

Bedding/Stratification

"Layering in sedimentary rocks. A single layer is a bed

Ripple Marks

"Small

Cross Bedding

"Sedimentary structures consisting of inclined layers within a larger bed

Turbidites

"Sedimentary deposits formed by turbidity currents (underwater avalanches of sediment and water)

Fossils

"Remnants or traces of once-living organisms preserved in rocks

Geologic Column

"A composite chart representing the entirety of Earth's history

Stratigraphic Correlation

"The process of matching up rock layers (strata) in different regions based on similarities in rock type

Transgression

"The inward migration of a shoreline due to a rise in sea level

Regression

"The outward migration of a shoreline due to a fall in sea level

Metamorphic Rock

"A rock that forms when a pre-existing rock (protolith) undergoes a solid-state change in response to changes in its environment (temperature

Protolith

"The original

Metamorphism

"The process of change that a rock undergoes in the solid state due to variations in temperature

Recrystallization

"A metamorphic process that changes the size and shape of mineral grains without changing the identity of the mineral."

Phase Change (Metamorphic)

"A metamorphic process where one mineral transforms into another mineral with the same chemical composition but a different crystal structure (a polymorph) due to changes in temperature or pressure."

Neocrystallization

"A metamorphic process involving the growth of new minerals that are different from those of the protolith

Pressure Solution

"A metamorphic process where mineral grains partially dissolve at points of high stress and the dissolved ions reprecipitate in areas of lower stress

Plastic Deformation

"A metamorphic process where rock is squeezed or sheared at elevated temperature and pressure

Metasomatism

"The change in the chemical composition of a rock due to reactions with hydrothermal fluids that introduce or remove chemical constituents."

Differential Stress

"Stress that is applied unequally from different directions

Foliation

"The parallel alignment of platy minerals (like mica) or the presence of alternating light and dark colored bands in a metamorphic rock

Slate

"A fine-grained

Phyllite

"A fine-grained foliated metamorphic rock