Igneous Rocks

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Ternary

A triangular graph in which the relative proportions of three minerals is used to classify a rock is called a __ diagram.

Vesicles

Basalt in the tops of subaerial lava flows and cinder cones commonly contains lots of:

Air

Basalt which erupts into this medium forms scoria, breccia and lava flows:

Gabbro

Beneath the basalt of the oceanic crust is a layer of what rock type?

Olivine

The first mineral to crystallize out of a melt:

Bowens Reaction Series

The order that minerals crystallize out of a melt:

Volcanic

Extrusive:

Ultramafic

Igneous rock, with more than 90% of dark minerals (mostly olivine), are referred to as:

95%

Igneous rocks make up about __ of the Earth's crust.

Meteorites

Impacts by __ during accretion of the Earth led to extensive melting.

Pegmatite

In some locations extremely course-grained __ masses with beautiful crystals occur with granite.

Divergent Boundaries

In what plate tectonic boundary settings is 3/4 of all extrusive rock produced?

Diorite

Large intrusions in the Andes Mountains are likely what rock type?

Quartz

The last element to crystallize as a magma cools:

Incompatible Elements

The last parts of a melt to crystallize as a magma cools:

Columns

During the cooling of a thick lava flow, contractional fractures form to create basalt:

Basalt

The lava flows of the Deccan Traps in India, the Siberian Traps in Russia, and the Columbia River Plateau of Washington are what rock type?

Silicon, Oxygen, Aluminum, Sodium, Potassium, Calcium, Iron, and Magnesium

The magma from which the minerals crystallize is rich in what eight elements?

Basalt

The most common extrusive volcanic rock:

Andesite

This lava is intermediate between felsic and mafic in composition and quite viscous:

Calcium Rich

This plagioclase composition is the first to crystallize out of a cooling melt?

Viscosity

This property of magma which governs its flow is determined by temperature, composition, and crystal content:

Pyroclastic

This term describes the texture of volcanic airfall rocks like tuffs:

Porphyritic

This texture involves visible crystals within a fine grained matrix:

Igneous Rocks

This type of rock is formed when molten magma cools:

Rhyolite, Andesite, and Basalt

Three types of lava:

Pyroclasts

Volcanic bombs, lapilli and volcanic ash are all called:

Subduction

Water is driven out of the oceanic lithosphere in __ zones, and it causes melting in the overlying mantle.

Diorite

A grey intermediate intrusive igneous rock:

Plutonic

Intrusive:

Conchoidal

Obsidian is easy to sharpen because it breaks with a __ fracture.

Gabbro

A dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt:

Melt

A decrease in pressure, an addition of water, an increase in temperature. Any of these can __ rock.

Batholith, Stock

A large irregular intrusion is a __, whereas a smaller irregular discordant is a __.

Melt

Decrease the pressure, add some water, increase the temperature. These are three ways that can result in this phenomenon:

Dike, Sill

A tubular discordant body is a __, whereas a relatively thin tubular concordant body intruded along bedding planes is a __.

Pumice

A volcanic rock that is a solidified glassy foam that floats:

Volcanic

An extrusive igneous rock can also be called:

Plutonic

An intrusive igneous rock can also be called:

Greenstones

Ancient lava flows, often altered to minerals like chlorite, are known as:

Fractional Crystallization

As magma cools, minerals typically crystallize from the melt at different temperatures. This is called:

Dark

Despite its felsic composition, obsidian is __ in color.

Vesicles

Beautifully crystallized species of zeolites, opal, quartz or calcite are frequently found in basalt:

Countertop

Because of its durability, granite has become a popular kitchen __ in modern houses.

Basalt

Ca-Plag, pyroxene and olivine form this type of lava:

Radon

Cellars sunk into soils formed over uraniferous granites can become a trap for __ gas.

Peridotite

Course-grained ultramafic rock:

Midocean Ridges

Decompression melting creates the ocean crust at what plate boundaries?

Pressure

Decompression melting occurs because of a decrease in __ as solid rock rises toward the surface.

Rhyolite

Felsic lava:

Light, Low

Felsic rocks are usually __ colored, and have a __ density.

Obsidian

Felsic volcanic glass:

Texture

Fine grained vs. course grained is an igneous rock classification based on:

Thin Sections

Generally, the mineral constituents of fine-grained extrusive igneous rocks can only be viewed in:

Phaneritic and Aphanitic

Geology jargon for course and fine grained respectively:

Phaneritic

Geology word for course-grained:

Porphyritic

Geology word for courser-grains in a finer-grained matrix:

Aphanitic

Geology word for fine-grained:

Magma

Geology word for melted rock:

Construction Stone

Granite is nearly always massive, hard and tough, and therefore it has gained widespread use as a:

Continental

Granitic rock is widely distributed throughout which type of crust on Earth?

Concordant, Discordant

If the intrusion is parallel to the country rock, the body is__. While if it cuts across the country rock, it is __.

Granite, Diorite, Gabbro, Peridotite

List four intrusive rocks ranging in order, from felsic to ultramafic:

Rhyolite, Andesite, Basalt

List three extrusive rocks ranging in order, from felsic to mafic:

Dark, High

Mafic rocks are usually __ colored, and have a __ density.

Partial Melting

Magma can be derived from preexisting rocks by this process:

Coarse

Magma cools slowly at depth, and as a result, intrusive igneous rocks are:

Lava

Magma extruded onto the surface either beneath water or air:

Lava

Magma extruded onto the surface is called:

Magmas

Most __ are mixes of melt and crystals, and gas bubbles.

Yellowstone

Most obsidian in archaeological sites in our region probably originated in:

Igneous Rock

Most radiometric dating is done on this general type of rock:

Granite

Name a common and widely occurring type of intrusive, felsic, igneous rock:

Amorphous

Obsidian is not a mineral because it is:

Tephra

Particles falling from the eruption clouds form layers of ash on the ground technically called:

Obsidian

Perhaps the sharpest known natural material:

Diorite

Phaneritic equivalent of andesite:

Gabbro

Phaneritic equivalent of basalt:

Granite

Phaneritic equivalent of rhyolite:

Mode of Occurrance

Plutonic vs. Volcanic is an igneous rock classification based on:

Tuffs

Pyroclastic deposits which have been lithified:

Volcanic

Pyroclastic rocks are clastic rocks composed of __ materials.

Granite

The central cores of major mountain ranges consist of intrusive igneous rocks, usually:

Emplacement

Stoping, assimilation, and forceful injection are three mechanisms that might explain the:

Solidus (Melting Point)

Temperatures can exceed the __ __ __ of a crustal rock due to compression at a plate boundary.

Continents, Oceans

The Earth's crust is about 35km thick under the __, but is only some 7-10km beneath the __.

AA, Pahoehoe

The __ form of lava flow is rough; the __ form of lava is smooth and ropey.

Bowens

The reaction series is important for understanding the idealized sequence of fractional crystallization of a magma:

Particle Size and Mineral Composition

The two most important variables used for the classification of igneous rocks. What are:

Quartz

The very last mineral to crystallize from a melt:

Rhyolite

The volcanic equivalent of plutonic granite is:

Pillows

These are very common in underwater basaltic flows and are diagnostic of an underwater eruption:

Intrusive

These igneous rocks are formed from magma that cools and solidifies within the earth:

Decompression

This cause of melting is responsible for mid-ocean ridges and ocean islands such as Hawaii:

Temperature Increase

This cause of melting is responsible for rhyolitic magmas in continental crust in collision zones such as the Himalayas:

Water

This cause of melting is responsible for the rise of andesitic magmas above subduction zones:

Pumice

This forms the grit in Lava Soap:

Magma

This is most commonly a mixture of melt, crystals, and gas bubbles:

Andesite

This lava is characteristic of subduction tectonic environments in active oceanic margins, such as the western coast of South America:

Igneous Rocks

What we do know about the composition of the mantle is derived from what general type of rocks?


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