Petrology, Volcanology, & Igneous Rocks

The difference between magma and lava is…

that magma is found below the surface, whereas lava is found above the surface

Which of the following rock types is the MOST viscous?

1. felsic

2. intermediate

3. ultramafic

4. mafic

felsic

The following are all intrusive igneous structures EXCEPT…

1. Batholith

2. sill

3. dike

4. lava tube

lava tube

Tuff is produced in an ___________________ igneous setting under conditions of _________________ viscosity.

1. intrusive; high

2. extrusive; high

3. extrusive; low

4. intrusive; low

extrusive; high

Enormous areas of extrusive igneous rocks which were erupted with low viscosity (flowed readily across the surface) are known as…

1. gabbros

2. sills

3. baccoliths

4. flood basalts

flood basalts

A rock that is phaneritic and felsic is called…

1. gabbro

2. granite

3. basalt

4. komaiiite

granite

A rock is aphanitic and mafic is called…

1. granite

2. rhyolite

3. andesite

4. basalt

basalt

Identify the following extrusive igneous texture.

1. phanaretic

2. glassy

3. porphyritic

4. fragmented

fragmented

Identify the following intrusive igneous texture.

1. glassy

2. aphanitic

3. porphyritic

4. phaneritic

phaneritic

Identify the following intrusive igneous texture.

1. aphanitic

2. fragmented

3. porphyritic

4. phaneritic

porphyritic

When magma crystalizes underground, _______________________ are formed.

1. intrusive igneous rocks

2. extrusive igneous rocks

3. volatiles

4. pyroclastic debris

intrusive igneous rocks

As compared to coarse-grained igneous rocks, all fine-grained igneous rocks…

1. cool and solidify more quickly

2. cool and solidify more slowly

3. solidify at higher temps

4. solidify at lower temps

cool and solidify more quickly

Coarse grained granite is most close in mineral composition to fine-grained ___________________.

1. andesite

2. basalt

3. gabbro

4. rhyolite

rhyolite

Basaltic lava that continues to flow after the surface has frozen, resulting in fragmentation of the solidified rock into sharp, angular fragments is known as _____________________________.

1. pahoehoe

2. andesitic lava

3. a’a

4. rhyolite

a’a

What volcanic feature is shown in the picture?

1. pahoehoe

2. rhyolite dome

3. lahar

4. fissure

rhyolite dome

When andesitic pyroclastics have been lithified (turned into solid rock) it is known as _______________

1. tephra

2. tuff

3. ash

tuff

All of the following are Cascades Range USA volcanoes EXCEPT _________________.

1. Mt. Hood

2. Mt. St. Helens

3. Mt. Tammany

4. Mt. Rainier

Mt. Tammany

What is the volcanic feature pictured here?

1. fissure

2. crater

3. conduit

4. caldera

caldera

What is the volcanic feature pictured here?

1. fissure

2. crater

3. caldera

4. conduit

conduit

Which type of volcano is pictured here?

1. stratovolcano

2. cindercone volcano

3. shield volcano

4. duncecap volcano

stratovolcano

Which of the following is the largest eruption?

1. Krakatoa

2. Pinatubo

3. Tambora

4. Yellowstone

Yellowstone

The hot spot track of the Emperor Seamounts and Hawaiian Islands tells us that _______________________.

1. the Pacific plate has been moving southeastward for the past 30 million years, and was stationary before that time

2. The Pacific plate has been moving northwestward for the past 30 million years, but moved northward before that time.

3. The Pacific plate has been moving northwestward for the past 30 million years, but was stationary before that time.

4. The Pacific plate has been moving southeastward for the past 30 million years, but was moving southward before that time.

The Pacific plate has been moving northwestward for the past 30 million years, but moved northward before that time.

The Colombia Basin igneous deposits are what kind of volcanic product?

1. flood basalts

2. pyroclastic flow

3. andesitic lava flows

4. ashfall

flood basalt

Which volcanic gas product was responsible for the deaths at Lake Nyos in 1986?

1. hydrogen sulfide

2. sulfur dioxide

3. methane

4. carbon dioxide

carbon dioxide

Which of the following volcanic hazards is the most dangerous to humans in the vicinity of the eruption?

1. basaltic lava flows

2. pyroclastic flows

3. ashfall

4. tsunamis

pyroclastic flows

All of the following are indications that an eruption MIGHT be imminent EXCEPT ___________________.

1. basaltic lava flows

2. pyroclastic flows

3. ashfall

4. tsunamis

pyroclastic flows

The Mt. St. Helens eruption in 1980 was which type of eruptive style?

1. explosive

2. effusive

3. offensive

explosive

Tuff and tephra differ in what way?

1. tephra is made in ash falls, while tuff is made in pyroclastic flows

2. tephra is silica-rich, while tuff is mafic

3. tephra is unconsolidated material, while tuff has been lithified

4. tephra is weak, while tuff will beat you up

tephra is unconsolidated material, while tuff has been lithified

Minerals that can display multiple habits are called…

1. multifaceted

2. polycrystalline

3. polymorphic

4. pseudomorphic

polymorphic

Which of the following is NOT a part of the definition of a “mineral?”

1. solid

2. faceted

3. homogenous

4. Naturally occurring

faceted

How many 4x symmetry axes does crystal A have?

1. 1

2. 2

3. 3

4. 4

3

Which of the following is NOT an example of luster?

1. Sticky

2. Metallic

3. Silky

4. Resinous

sticky

Gemstones do not display faces, instead they have…

1. facades

2. cleavage planes

3. facets

4. sides

facets

Which of the following exhibits conchoidal fracture?

1. calcite

2. muscovite

3. feldspar

4. quartz

quartz

The mineral pictured is scratched BY corundum but CAN scratch apatite and flourite. What is it likely to be?

1. Topaz

2. Garnet

3. Feldspar

4. Quartz

Garnet

The pictured mineral can be scratched with a penny. What is it likely to be?

1. Calcite

2. Feldspar

3. Quartz

4. Kyanite

Calcite

The following mineral is an example of what kind of silicate?

1. double-chain

2. sheet

3. independent

4. framework

sheet

Galena is an example of what type of mineral?

1. Halide

2. Carbonate

3. Sulfide

4. Native Metal

Sulfide

What simple field test could you perform to definitely identify calcite?

1. smash it into pieces with your rock hammer and examine the cleavages

2. taste it

3. hold it up to a magnet

4. Drip diluted HCl on it and observe fizzing

Drip diluted HCl on it and observe fizzing

The silicate tetrahedron that forms the backbone of all silicate minerals is composed of silicon and what other element?

1. Magnesium

2. Oxygen

3. Iron

4. Carbon

Oxygen

The Single property that can be used to identify any mineral is ________.

1. color

2. luster

3. cleavage

4. hardness

5. none of the above, multiple properties must be considered

none of the above, multiple properties must be considered

Cleavage in minerals refers to …

1. a tendency to break in an irregular pattern

2. a tendency to break along planes of weakness

3. the sharpness of edges between crystal faces

4. the development of distinct crystal faces

a tendency to break along planes of weakness

The New Age practice of surrounding one’s self with crystals has a strong positive effect on…

1. mental health

2. the immune system’s response to illness

3. the prospects for world peace

4. the bank accounts of rock shop owners

the bank accounts of rock shop owners

Name 6 characteristics of minerals?

1. homogenous

2. naturally occurring

3. solid

4. definable chemical composition

5. orderly internal structure

6. inorganic (generally)

1. Euhedral

2. Anhedral

1. WELL developed faces on crystals

2. POORLY developed faces on crystals

Isometric Symmetry

Roughly equal in three dimensions

Tetragonal Symmetry

roughly equal in two dimensions

Orthombic Symmetry

all three dimensions are different values

Monoclinic Symmetry

orthombic, but “bent” in one plane

Hexagonal Symmetry

having two dimensions represented by six faces

What are polymorphic minerals? Give an example:

minerals with the same chemical composition but arranged in a different internal structure

• ex: Diamond & Graphite

Name the different mineral properties

1. color

2. streak

3. luster

4. hardness

5. Specific Gravity

Luster

Defined as the wat the mineral “scatters light”

• Silky, Glassy, Satiny, Resinous, Pearly, Earthy, Metallic

Hardness of a mineral

the mineral’s ability to resist being permanently “scratched”

• Frederich Mohs Scale: higher numbers can leave a “mark” on lower numbers.

What are the different types of Crystal Habits?

1. Bladed: slender and flattened

2. Sheet: muscovite, biotite, lepidolite

3. Columnar: only revealing crystal faces in two dimensions, irregular at edges

4. Fracture: glassy “minerals” like obsidian have no real cleavage, instead they break with what is called “conchoidal fracture”

5. Cleavage: the tendency of a mineral to break along planes (cleavages) of weakness related to the atomic structure of the mineral

Which are the most abundant class of Mineral?

1. Oxides

2. Silicates

3. Sulfides

4. Sulfates

5. Halides

6. Carbonates

7. Native Metals

Silicates

What are the building blocks of all silicates?

silica tetrahedron (SiO4)

What are the 4 types of magma in order from greatest → least amount of silica?

1. Felsic

2. Intermediate

3. Mafic

4. Ultramafic

The MORE volatiles present in magma, the ___________________ (lower/higher) the viscosity. The LESS volatiles present, the ____________________ (lower/higher) the viscosity.

lower; higher

The higher the silica content present in magma, the _________________ (lower/higher) the viscosity.

higher

Intrusive Structure: Dikes

vertical, tubular bodies

Intrusive Structure: sills

horizontal, tubular bodies

Intrusive structures: Laccoliths

essentially a sill which is continuously supplies with new magma, which then bulges upward

Intrusive Structure: Plutons

blob-shaped bodies of magma which rise through the crust as a single entity before (for some reason) stopping their progress and cooling in place

Intrusive Structure: Batholiths

essentially HUGE HUGE plutons

What are the 2 Extrusive Settings?

1. Explosive: Ash fall, Lava domes, Ash flow

2. Non-Explosive: Lava fountain, Lava flow

What three factors control the rate of cooling?

1. Depth: deeper the site of cooling = slower cooling

2. Morphology: more spherical magma body = slower cooling

3. Presence of Groundwater: presence of groundwater = fast cooling

Describe ALL of the 3 Igneous Textures

1. Fragmental: igneous “fragments” that have been welded together. Typically produced by extrusive processes

2. Glassy: have few or no crystals at all

3. Crystalline

   • Phanaretic: large crystals

   • Aphanitic: small crystals

   • Porphyritic: large crystals of one or more minerals “floating” in a matrix of smaller crystals (invisible) of other minerals

Categorize Different Types of Lava Flows

1. Andesitic: glacier like

2. Ryolitic: high viscosity, tend to form domes

3. Columnar joints

4. Basaltic: Lava tubes

   • Pahoehoe

   • a’a

Pyroclastics

1. Andesitic Pyroclastics

   • Ash

   • Pyroclastic Flow

2. Basaltic Pyroclastics

   • Lapilli: formed by popping gas pockets which ejects the material

   • Bombs: big lapilli

   • Pelee’s hair

Deposits

1. Tephra: unconsolidated pyroclastics of all types

2. Tuff: ash mixed with lapilli

3. Ignimbrite: a cohesive sheet of tuff formed from pyroclastic flow

4. Blocks: chunks of previously existing volcano torn loose by the eruption

5. Debris flow: blocks mixed with melted snow

6. Lahar: saturated mixture of debris

Fissure

Crater

Caldera

Shield Volcanos

Cindercone Volcano

Stratovolcanos

1. Eruptive Style: Effusive

2. Eruptive Style: Explosive

1. consisting mainly of low-viscosity lava flows, tends to create shield volcanos

2. consisting of both high-viscosity lava, pyroclastics and ash fall, tends to create cindercones