Lesson 5 Questions: Igneous Rocks

Match the aphanitic extrusive rock type with its phaneritic intrusive compositional equivalent below 1. andesite 2. rhyolite 3. basalt diorite gabbro granite

1. diorite 2. granite 3. gabbro

Match the rock types below with their textural states: 1.phaneritic 2. aphanitic andesite granite basalt diorite gabbro rhyolite

1. granite 1. diorite 1. gabbro 2. andesite 2. rhyolite 2. basalt

List the minerals in the order in which they crystallize from a melt.

1. olivine 2. pyroxene 3. amphibole 4. biotite 5. potassium 6. feldspar 7. muscovite 8. quartz

Magma that is forcefully ejected into the atmosphere as particles is known as:

a pyroclastic material

What is supposed to be in box C?

amphibole

Pegmatite refers to

an extremely coarse texture

What is supposed to be in box P?

andesite

Igneous rocks with a texture that is so fine-grained that the crystals are too small to see is:

aphanitic

What is supposed to be in box M?

basalt

What is supposed to be in box D?

biotite

A sill is a

concordant, tabular body of intrusive igneous rocks.

Natural glass, such as obsidian, forms when magma:

cools too rapidly for crystals to form

What is supposed to be in box O?

diorite

If early-formed crystals settled out of a magma, the magma would tend to be

enriched in silica.

Any individual volcano will always erupts magmas of the same type.

false

At a linear volcanic chain, such as the Hawaiian Islands, the rocks are oldest over the hot spot and become progressively younger away from the hot spot.

false

Dikes are concordant and sills are discordant.

false

It has been found that the minerals will crystalize starting at the top of the Bowen's diagram, but will start weathering at the bottom of the diagram.

false

Magma chambers generally exist at depths of 100's of km beneath spreading ridges.

false

Phaneritic textures indicate that the rock formed under extrusive conditions as the lava cooled and crystallized on Earth's surface.

false

Plutons form within the peaky structure of a volcano.

false

Rhyolite forms when a mafic magma cools on Earth's surface.

false

The discontinuous branch of Bowen's reaction series includes various compositions of plagioclase, from calcium-rich to sodium-rich.

false

Volcanoes always erupt magmas of the same type.

false

A magma composed of more than 65% silica is referred to as:

felsic

What is supposed to be in box Q?

felsic

What is supposed to be in box K?

mafic

What is supposed to be in box F?

muscovite

Plutonic igneous rocks:

solidify below the surface of the ground AND form by crystallization of magmas intruded into surrounding rocks.

Most igneous rocks are classified by:

texture and composition

Bowen's Reaction Series explains the order of mineral formation with decreasing temperature.

true

Bowen's Reaction Series explains why Si-rich minerals are the last to crystallize from a magma.

true

Felsic lavas would tend to be slow moving, thick, and move only short distances.

true

Geologists generally agree that batholiths are emplaced by forceful injection.

true

In igneous rocks with porphyritic texture, the larger minerals are phenocrysts, and the smaller minerals collectively make up the groundmass.

true

Laccoliths are more similar to sills than they are to dikes.

true

Mafic magma is silica poor and may be derived from melting of Earth's upper mantle.

true

Magma composition may change by crystal settling.

true

Magmas formed at subduction zones are mostly intermediate or felsic

true

Pegmatites are composed of very large crystals that formed from water-rich magma.

true

Porphyritic textures suggest a complex cooling and crystallization history. one that includes at least two rates of crystallization.

true

The process of assimilation includes the incorporation of felsic country rock.

true

The process of assimilation partly explains why felsic intrusive rocks are much more common than mafic intrusive rocks

true

The process of assimilation results in the cooling of an intruding magma.

true

Tuff is made up of pyroclastic materials.

true

What is supposed to be in box I?

ultramafic

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-plutonic igneous rock -formed from the crystallization of Mafic magma or lava -gabbro

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-plutonic igneous rock -formed from the crystallization of Ultramafic magma -peridotite

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-plutonic igneous rock -formed from the crystallization of a Felsic magma or lava -granite

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-plutonic igneous rock -formed from the crystallization of an intermediate magma or lava -diorite

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-volcanic igneous rock -formed from the crystallization of Felsic magma or lava -obsidian

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-volcanic igneous rock -formed from the crystallization of Felsic magma or lava -pumice

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-volcanic igneous rock -formed from the crystallization of Felsic magma or lava -rhyolite

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-volcanic igneous rock -formed from the crystallization of Mafic magma or lava -basalt

Select all that help identify this Igneous Rock along with the name of the Igneous Rock

-volcanic igneous rock -formed from the crystallization of an intermediate magma or lava -andesite

Place the minerals in the correct sequence that occurs during Bowen's Reaction Series as the magma cools, from first (1) the first mineral in the Discontinuous Branch to the last (8) mineral to form (Note the Continuous Branch is not in this listing).

1. olivine 2. pyroxene 3. amphibole 4. biotite 5. potassium feldspar 6. muscovite 7. quartz

Match the following igneous rock types with the correct type magma/lava 1. ultramafic 2. mafic 3. intermediate 4. felsic gabbro rhyolite granite basalt andesite peridotite diorite

1. peridotite 2. gabbro 2. basalt 3. andesite 3. diorite 4. rhyolite 4. granite

Match the following images to the correct igneous texture type.

1. porphyritic texture 2. vesicular texture 3. aphanitic texture 4. phaneritic texture 5. glassy texture 6. pyroclastic texture

Match the intrusive igneous rock body with the appropriate adjective describing the relation of the rock body with the country rock. 1. discordant 2. concordant batholith laccolith stock dike sill

Discordant- stock, batholith, dike Concordant- sill, laccolith

The most widely accepted explanation for chains of volcanoes in the oceans is that they formed at:

Hot spots, not interactions of plate boundaries

intrusive igneous rocks:

Solidify below the surface of the ground AND form by crystallization of magma intruded into surrounding rocks

A granite would form under conditions that included

a felsic magma cooling in the subsurface

A basalt would form under conditions that included

a mafic magma cooling on Earth's surface

What is supposed to be in box L?

gabbro

What is supposed to be in box R?

granite

The process of assimilation

includes the inclusion of country rock in an intrusive magma, the melting and incorporation of inclusions, can explain some of the felsic mineral enrichment of a mafic magma and results in the cooling of a magma body.

A porhyritic texture indicates that the rock or rock body

initially cooled slowly, then more rapidly.

What is supposed to be in box N?

intermediate

What is supposed to be in box A?

olivine

What is supposed to be in box J?

peridotite

Batholiths typically contain

phaneritic rocks composed predominantly of non-ferromagnesium silicates.

What is supposed to be in box H?

plagioclase feldspar

Igneous rocks with a two-stage intrusive-extrusive origin are recognized by a texture that is:

porphyritic

What is supposed to be in box E?

potassium feldspar

A vesicular felsic rock is called a:

pumice

Igneous rocks formed by explosive volcanic activity have a texture that is termed:

pyroclastic

What is supposed to be in box B?

pyroxene

What is supposed to be in box G?

quartz

According to Bowen's reaction series, you would not find a mineral assemblage containing

quartz and olivine

A dark colored igneous rock with no visible crystals cooled:

quickly on the Earth's surface.

Aphanitic, phaneritic, and porphyritic are textural terms that:

refer to fine-grained, course-grained, and mixed-grained crystal sizes, respectively, refer to formation by slow cooling, fast cooling, and mixed cooling rates, respectively, and are indicative of volcanic, plutonic, and mixed plutonic-volcanic origins, respectively

What is supposed to be in box S?

rhyolite