Volcanism and Plutonism

What is “Aa” (besides being the first word in the geological dictionary)?

 

Question options:

	a)  a basalt lava flow where the lava develops a sharp jagged surface called “clinker”
	b)  a pyroclastic fragment that is larger than ash but smaller than a bomb, found on Cinder Cones
	c)  a type of “obsidian” with conchoidal fractures like broken glass found in a Caldera
	d)  a type of blocky granite that is found on a Cinder Cone such as Mount Lassen in California
	e)  a plutonic landform that is larger than a stock but smaller than a batholith

a basalt lava flow where the lava develops a sharp jagged surface called “clinker”

Name a rock and landform characteristics that occur at a divergent oceanic plate margin

          

Question options:

	a)  these eruptions make high lava plateau at a Mid-oceanic ridge, such as seen at Iceland
	b)  pillow lavas of basaltic composition occur along fissure eruptions on the ocean floor
	c)  scoria and cinder cones occur here because the mafic lava is in a water-rich environment
	d)  granite batholiths occur here because this is where continental crust is being constructed
	e)  tuffs and pyroclastic fragments are generated by the explosive eruptions at divergent margins

pillow lavas of basaltic composition occur along fissure eruptions on the ocean floor

In which ocean is Hawaii found?

Question options:

	a)  Arctic
	b)  Pacific
	c)  Indian
	d)  Atlantic

Pacific

Mark the thing(s) that is/are the DIFFERENT for SHIELD VOLCANOES and LAVA PLATEAUS.

Question options:

Magma composition

viscosity

shape of opening

gas content

All of them

Which texture indicates that the lava/magma had a high gas content?

Question options:

a)

aphanitic

b)

phaneritic

c)

vesicular

d)

glassy

Vesicular

Which type of volcanic landform is the Columbia River Plateau?

Question options:

a)

shield volcano

b)

lava plateau

c)

composite volcano

d)

shield volcano

lava plateau

Which type of lava flow has the slowest moving flow front?

Question options:

	a)  pahoehoe
	b)  aa
	c)  cinder eruptions
	d)  pele's hair

aa

Select the material with the lowest viscosity (on this list).

Question options:

a)

corn syrup

b)

motor oil

c)

water

d)

air

air

What characteristics / features of the magma and the “plumbing” system are required to exist for the development of a landform called a “lava plateau”

Question options:

a)

low viscosity + mafic magma + low gas + erupting from a fissure to form a rock called basalt

b)

high viscosity + felsic magma + low gas + fissure eruption forming a rock called porphyritic andesite

c)

any viscosity and any gas content, only need a fissure eruptions that form granite layering

d)

low viscosity + felsic magma + high gas + erupting from a conduit to form a rock called rhyolite

e)

high viscosity + mafic magma + high gas + erupting from a conduit to form a rock called scoria

low viscosity + mafic magma + low gas + erupting from a fissure to form a rock called basalt

Find the correct characteristic and location for development of a lava called “pahoehoe"

Question options:

a)

b)

a high gas, felsic lava forming on a Lava Dome as seen at Mount Lassen in California

c)

a fissure eruption of rhyolite as seen in the collapse calderas at Yellowstone National Park

d)

a plutonic igneous rock made of granite as seen when you climb Stone Mountain in Georgia

e)

a viscous, fast moving – vesicle rich pyroclastic flow as seen at Mount Pinatubo in the Philippines

a low gas, mafic lava forming on a Shield Volcano as seen in Hawaii

The magma composition for a magma feeding a composite volcanoes changes during an eruption.

Question options:

a) True

b) False

True

The Cascades volcanoes include Mt. Rainier.  This volcano is found in California.

Question options:

	a) True
	b) False

False

Give the correct set of factors that will cause a landform called a “cinder cone” to form?

Question options:

a)

Plutonic Environment + Felsic Magma + a fissure filling + low gas content.

b)

Plutonic Environment + Mafic Magma + a conduit filling + high gas content.

c)

Volcanic Environment + Low Viscosity + High gas content + conduit eruption.

d)

Hypabyssal Environment + felsic magma + low viscosity + fissure filling.

e)

Volcanic Environment + High Viscosity + Low gas content + fissure eruption

Volcanic Environment + Low Viscosity + High gas content + conduit eruption.

Which is the largest pyroclastic size (from this list)?

Question options:

	a)  bombs
	b)  cinders
	c)  ash

bombs

Cinder cones are built completely of pyroclastic materials.

Question options:

	a) True
	b) False

True

Porphyritic texture is often formed in composite volcano systems.  Which forms while the magma is still under the surface?

Question options:

	a)  phenocrysts
	b)  glass
	c)  vesicles
	d)  ground mass

phenocrysts

Which igneous rock type is likely to be found in a lava dome?

Question options:

	a)  rhyolite
	b)  diorite
	c)  basalt
	d)  peridotite

rhyolite

Name a “Park” (and State where it is located) where you can see a landform called a “collapse caldera” … and name a rock you can expect to find here.

Question options:

a)

A caldera made of granite is in the Grand Canyon National Park in Arizona (Earth’s largest hole)

b)

A collapse caldera made of rhyolite is seen at Mount Rainer in Washington due to a lahar eruption

c)

A caldera made of tuff is seen at Crater Lake National Park (part of the Cascade Volcanic Range)

d)

A collapse caldera made of basalt is seen at the top of Mauna Loa National Park in Hawaii

e)

A caldera made of gabbro is seen at Elberton Park in Georgia (part of the Appalachian Mountains)

A caldera made of tuff is seen at Crater Lake National Park (part of the Cascade Volcanic Range)

Which is more explosive?

Question options:

	a)  caldera
	b)  lava dome

caldera

Lava domes are fed magma through a conduit.

Question options:

a) True

b) False

True

When a fissure fills with magma and crystallizes into plutonic rock, what is formed?

Question options:

a)

a dike

b)

a sill

c)

a brecciated neck

d)

a columnar neck

a dike

Recall Bowen's Reaction Series. Olivine reacts with the magma to produce which mineral?

Question options:

a)

Muscovite Mica

b)

Biotite Mica

c)

Augite (Pyroxene)

d)

Hornblende (Amphibole)

Augite (Pyroxene)

Columnar jointing found in some plutonic rock is formed due to:

Question options:

a)

fracturing during unloading of overlying rock.

b)

movement of the magma conduit over time.

c)

contraction during the cooling process.

d)

changes in magma composition following Bowen's Reaction series

contraction during the cooling process.

It is possible for different magma compositions to make the same volcanic landforms.

Question options:

a) True

b) False

False

Name characteristics that will distinguish rocks forming in a deep plutonic environment from those forming in a volcanic environment.

Question options:

a)

Plutonic rocks are phaneritic with more hydrous minerals, while volcanic rocks will be aphanitic and can have vesicles

b)

This is a trick question because all igneous rocks can be found in both environments.

c)

Plutonic rocks are usually felsic in composition, while volcanic rocks are usually mafic

d)

Volcanic rocks are composed of minerals like olivine and pyroxene (higher up in Bowen’s reaction series) while plutonic rocks have minerals like feldspar and quartz (lower in Bowen’s series)

e)

Volcanic rocks only have crystalline minerals, while plutonic rocks are often composed of glass

Plutonic rocks are phaneritic with more hydrous minerals, while volcanic rocks will be aphanitic and can have vesicles

In which state is Mt. Rushmore found?

Question options:

a)

Minnesota

b)

South Dakota

c)

Nebraska

d)

Wyoming

South Dakota

What type of pluton is Stone Mountain?

Question options:

a)

Diorite dome

b)

laccolith

c)

batholith

d)

stock

laccolith

In which US state is the Sierra Nevada Batholith found?

Question options:

a)

Oregon

b)

California

c)

Washington

d)

Arizona

California

The magma in a small underground chamber had a small eruption to make a lava dome, and all the remaining magma crystallized in the chamber to form a landform that has an area of 50 sq. miles. This underground landform is..

Question options:

a)

a rhyolite dike

b)

a gabbro batholith

c)

a basalt sill

d)

a granite stock

e)

a pumice-rich collapse caldera

a granite stock

An intermediate rock that can be formed in a deep plutonic environment is

Question options:

a)

peridotite

b)

diorite

c)

gabbro

d)

granite

Diorite