GLY101 ch 2-12

Which of the following are evidence for continental drift, and which are evidence for plate tectonics?

Continental drift:

• Matching fossils and rocks

• Matching coastlines

• Warm places glaciated

• Cooler places with tropical fossils

Plate Tectonics:

• GPS measurements

• Mid-Ocean ridge found

• Ocean trenches found

• Lined-up earthquakes

• Paleomagnetism showing moving rocks

How did scientists first figure out plates could sink into the interior of the planet, since no one can see this happening?

Lines of progressively-deeper earthquakes near arcs and trenches

Which of the following are NOT evidence Wegener used to construct the idea of Continental Drift?

Earthquake locations lined up with crustal features

Match the layer of the Earth with the description that fits it best!

Crust: Low density layer

Inner Core: Highest density layer

Outer Core: Liquid layer

Mantle: Largest layer by volume

Lithosphere: Layer plates are made from

Asthenosphere: Layer that moves the plates around

Which layer of the Earth can move internally or flow to allow the plates to move around on it?

Athenosphere

What makes continental plates different than oceanic plates?

Continental plates are ductile and can flow internally

What term is used for a boundary between a continent and an ocean basin without relative motion between them?

Passive- no active boundary / no movement

Why do high mountains like the Alps and Himalayas form when continents collide?

The materials of continental plates are similar in density and don't subduct beneath one another

What feature is associated with crustal divergence?

Mid-ocean ridge

Why do continents generally not subduct?*

Continents are too low in density to subduct

Which of these are features found at rift zones?*

Grabens and Faults and rifts at 120° angles

What happens as newly formed oceanic crust moves away from the mid-ocean ridge?

The crust gets colder

Other than midocean ridges, where on Earth is the best example of current (active) rifting?

East Africa

How is magma generated at divergent boundaries?

Decreased pressure

As a rift forms on a continent, what feature can form next?*

Ocean basin

What famous transform fault is known for being the boundary between the Pacific Plate and North American Plate in California?

San Andreas fault

What type of motion occurs at a transform boundary? Plates move ____________.

side to side

What makes transform boundaries different than other boundaries?

Transform has less volcanoes

Why are piercing points important with transform boundaries?

They track movement

What are the ways transform faults move?

Left (sinistral) and right (dextral)

What makes the Hawaiian hot spot different than the Yellowstone hot spot?

Different types of tectonic plates

• The thicker continental plate under Yellowstone causes less frequent, but more destructive, eruptions.

According to the Wilson Cycle, what feature or process is most likely to occur after collision and formation of a supercontinent?

Rifting

What features or processes are common in hot spots?

Volcanism

A line of shallow earthquakes with little or no volcanism is likely evidence of what type of plate boundary?

transform

Which plate boundary has the largest and deepest earthquakes?

Subduction

Why are there not as many earthquakes or volcanoes on the east coast of North America as the west coast of North America?

It is not close to a plate boundary (passive margin).

We are not able to get rocks from deep within the Earth. What is the most direct source of information that allows us to draw conclusions about the interior?

Seismic waves

Of these, what boundary generally produces new liquid magma?

Subduction

What happens to the crust as you move towards the mid-ocean ridge?

the crust gets younger- new ocean floor created

Which plate boundary is least likely to be dangerous to humans?

Mid-ocean ridge: not near humans, no large earthquakes or volcanoes

Which tectonic setting places the asthenosphere farthest from the surface?

Continental collisions

What is the biggest difference between hot-spot volcanism in an island chain and plate tectonic volcanism in an island chain?

Hot spots have age trends

Which of the following does not cause an increase in mineral precipitation?

Heating a fluid

What is the most common mineral formed by life?

Calcite

When a mineral precipitates from solution, it ____________.

crystallizes into a crystal

Why are mica minerals "like a sandwich"?

Because layers of weak bonds cause the platy mineral to easily cleave into sheet

Which of the following is NOT an arrangement of silica tetrahedra in silicate minerals?

Triple chain

What elements are in the silica tetrahedra, the basic unit of silicate minerals?

4 oxygens and 1 silicon

Which mineral group provides important ores of copper, lead, and zinc, among other metals?

Sulfides

Why are only some minerals found as native minerals? For example, iron and aluminum are almost never found as native elements in nature.

Most elements are too reactive to occur in native form

What is the most common origin of carbonate minerals in nature?

Made by marine life

Regarding the Mohs Hardness Scale table, if a mineral scratches the copper penny but NOT the glass plate, then the hardness is around ____.

4.5

Which mineral identification property involves making powder of a mineral?

Streak

What luster determination is a good starting point for mineral identification?

Metallic/non-metallic

Cleavage is a product of ____________ in a mineral's atomic structure.

weakness

Which of the following is true about minerals?

Minerals can only be made naturally

What are the two (2) most abundant elements in Earth's crust?

Silicon (Si) & Oxygen (O)

What is the chemical formula of the silica tetrahedra, the building block of all silicate minerals?

SiO4

What makes native elements different than all other minerals?

They contain only one element

Select one process by which minerals are NOT made?

Acid reactions from rain

Which mineral group is composed of a 3-D framework of silica tetrahedra?

feldspar

What controls a mineral's color?

Elements present

Which of these is actually a mineral?

icicle hanging from a pine tree

Why might a single mineral (like pyrite) have several different crystal habits?

Atoms in its structure can be arranged differently

Where do igneous rocks with a coarse-grained (phaneritic) texture form?**

deep under the surface.

How does the silica content affect the behavior of magma?

Higher silica makes the magma more viscous

Which rock composition has the most amount of iron and magnesium?

ultramafic

What causes igneous rocks to develop a fine-grained (aphanitic) texture?

Fast cooling

A basaltic intrusion that cuts across layers of sedimentary rocks is called a _______.

dike

Examine Bowen's Reaction Series diagram. If a rock contains amphibole, potassium feldspar (orthoclase), and quartz, if the rock is heated, which mineral would melt first?

quartz

The Bowen diagram shows that quartz both crystallizes from cooling magma and melts from heated rock at the lowest temperature.

Examine Bowen's Reaction Series diagram. Which mineral has the highest temperature of crystallization?

olivine

Examine Bowen's Reaction Series diagram. As a felsic magma cools, which mineral would be the last to crystallize?

quartz

What is the process by which decompression melting produces magma at divergent plate boundaries?

reduction of pressure at constant temperature

If volatiles such as water vapor and carbon dioxide are added to a rock, what will happen to the melting temperature?

The melting temperature of a rock will decrease.

What does a P-T diagram of the mantle show?

It shows how pressure and temperature increase with depth.

The crystallization process in which a rising magma diapir incorporates some of the surrounding country rock so that the chemistry of the magma changes is called _____.

assimilation

Unmelted pieces of country rock incorporated within the igneous rock mass are called _______.

xenoliths

Crystal settling would be another name for ______.

fractional crystallization

Partially melting an ultramafic rock produces a magma with a(n) _________ composition.

mafic

As magma travels up from the asthenosphere through the lithosphere into continental crust, how will fractional crystallization change the chemistry of an ultramafic magma?

The ultramafic magma will become more mafic.

Explosive silica-rich volcanoes will be located mostly at ______.

convergent plate boundaries with subduction zones

Deep-sea hydrothermal vents (black smokers) are most commonly located at what plate boundary?

divergent boundaries of the mid-ocean ridge

The largest type of volcano is called a _______ volcano and is characterized by broad, low-angle flanks, a small vent or groups of vents at the top, and basaltic magma.

shield volcano

A _______ volcano has steep flanks, symmetrical cone shapes, distinct crater at the top, and a silica-rich magma that results in an explosive eruption style.

stratovolcano (or composite volcano)

Which of these relatively recent volcanic eruptions formed a caldera?

Yellowstone

What kind of volcanoes make up the Hawaiian Island Chain?

shield volcanoes

Most volcanoes on the sea floor erupt ________.*

Quietly with basaltic magma

Why does partial melting occur?

Because some minerals have lower melting points than others

Which of these is NOT a means by which magmas are generated in the Earth?*

Liquid melting

What does the Bowen Reaction Series show about the mineral composition of igneous rocks?*

The minerals in igneous rocks form in separate groups that depend on the temperature at which they crystallize.

Bowen's Reaction Series has been expressed as a Y-shaped diagram containing how many minerals?

8

A rock with aphanitic texture and dark color is best identified as a _______________.*

basalt