Earth- An Introduction to Physical Geology #3

Which of the following factors describe the metamorphic conditions in a subduction zone?

-low temperature -high pressure

Which of the following factors describe the metamorphic conditions at a mid-ocean ridge?

-low temperature -low pressure -hot, watery fluids

Which of the following describes the orientation of slaty cleavage and mineral grains in relationship to the stress applied?

-slaty cleavage is parallel to the direction of the weakest stress applied.-mineral grains are oriented parallel to the direction of the weakest stress applied.

What is the temperature range over which hydrothermal metamorphism will occur?

0-400 degrees celsius

1.____ are two examples of building minerals, whereas 2.____ are two examples of industrial minerals.

1. gypsum and calcite; 2. sulfur and sylvite

Rank from youngest = 1 (most recent) to oldest = 4.

1.) Intrusion of light colored igneous rock2.) Metamorphism of rock that became the dark colored metamorphic3.) Lithification (the creation of sedimentary rock) from sediment4.) Deposition of Sediments

What is the half-life of potassium-40?

1.3 billion years

A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many total atoms will be in the container after 3 months?

100 atoms

What is the minimum depth at which subduction zone metamorphism will occur?

13km

If 235U has 92 protons, how many neutrons does it have?

143

Each isotope has a unique half-life. The half-life of an isotope is the time taken for half of the starting quantity to decay (with a ratio of 1:1). After two half-lives, there will be one-fourth of the original parent sample and three-quarters would have decayed to the daughter product (with a ratio of 1:3). After three half-lives, the ratio becomes 1:7, and so forth. The graph, for instance, shows that assuming the half-life of a sample is 4 months, then in 4 months, there will be 0.5 gram of the parent element and 0.5 gram of the daughter element will be produced. In month 8 (which is two-half-lives), there will be only 0.25 gram of parent element left and 0.75 gram of daughter element; that is, one-fourth of the parent sample (in red) is left, and in month 12, there is only one-eighth of the parent element. You attend a geology lab where you are asked to estimate the age of a fossil. The ratio of parent to daughter elements in the fossil sample is 1:7. You know that fossils are the remains of living organisms, which have some amount of C-14 isotope. The C-14 isotope, which has a half-life of 5730 years, begins to decay as the organism dies. What would be your estimation of the fossil's age?

17,190

What is the effective maximum range for carbon-14 dating?

70,000 years

What is the definition of an inclusion?

A fragment of one rock unit enclosed in another rock unit

Which of the following is an example of a numerical date?

A meteorite impacted the Earth sixty-five million years ago.

Replaced

A molecule of mineral replaces molecule of the fossil.

What would the presence of a fault breccia tell you about the history of an area?

A transform fault was present. Brittle deformation occurred.

Match the nonmetallic resource with its main category (building material or industrial mineral) and its main use:

A. garnet1. industrial mineral - abrasiveB. calcite/limestone2. building material AND industrial mineral - used widely in many areasC. apatite3. industrial mineral - fertilizer, specifically phosphateD. diamond4. industrial mineral - abrasiveE. gypsum5. building material - plaster, sheetrockF. sylvite6. industrial mineral - fertilizer, specifically potash

What is meant by the statement "Every metamorphic rock has a parent rock"?

All metamorphic rocks are created only through the change of preexisting rock.

If a rock contains ten different kinds of fossils, which of the following must be true?

All of the organisms had to be alive when the rock was deposited

If a sequence of sedimentary units is cut by a fault, what does the principle of cross-cutting relationships tell a geologist?

All of the sedimentary units must have been deposited and lithified before being cut by the fault.

Bauxite is an ore of what metal?

Aluminum

Prolonged tropical weathering of specific kinds of bedrock can produce deposits of which ore?

Aluminum

What is an isotope?

An atom that has more or fewer neutrons than it should

Which of the following statements accurately contrasts an index fossil with a fossil assemblage?

An index fossil is an individual fossil used to correlate different rock layers of the same age; a fossil assemblage is a specific combination of fossils that is used to more precisely date a rock layer.

What is an ore?

An ore is a useful metallic mineral that can be mined at a profit.

What is an index fossil?

An organism that was geographically widespread but limited to a short span of geologic time

What characteristic most directly DISTINGUISHES an angular unconformity from a nonconformity?

Angular unconformities separate rock layers along nonparallel surfaces.

Mineral resource

Any deposit on earth that could be mined

Inclusions

Any geologic material included in another must be older than the other.

cross cutting

Any geologic material that cuts across a rock must be the younger material.

What is the main mineral source of phosphorous in phosphate fertilizers?

Apatite

Percents help us understand how the parts of something, like a pizza slice or a natural event, relate to the entirety of the pie or Earth's history. Calculate the length of time of the following events as a percent of Earth's age. Round the age of Earth to 5 billion years old.

Assume the length of recorded history is 5,000 years. It is correct to say recorded history represents 0.0001 percent of geologic time.Evidence of abundant fossils date back to 540 million years ago. It is correct to say this represents 10.8 percent of geologic time.If human-like ancestors have been around approximately 5 million years, it is correct to say this represents 0.1 percent of geologic time.

Prolonged tropical weathering of specific kinds of bedrock can produce deposits of which mineral?

Bauxite

What is the primary ore of aluminum, and how does it form?

Bauxite is the primary ore of aluminum. Bauxite forms in tropical conditions when aluminum-rich source rocks undergo prolonged chemical weathering.

Non-metallic resources are generally divided into two broad categories, name one of them:

Building

________ metamorphism tends to occur in regions where massive amounts of sedimentary or volcanic materials accumulate in a subsiding basin.

Burial

Which of the following minerals does not form as a result of magmatic segregation?

Calcite

John is assisting a geologist who has traveled across the world and collected a few samples. He asks John to classify the samples that can be dated using carbon-14 and uranium-235 (or U-235). All organic materials contain carbon and are dated using C-14; inorganic materials are dated using any radioactive element, such as uranium, rubidium, potassium, and thorium, except carbon. Now, help John group the samples.

Carbon-14 dating: wood piece, Egyptian mummies U-235 dating: gneisses, volcano ash, granite

How do minerals accumulate in placers, and what are two examples of such minerals?

Certain heavy minerals, such as cassiterite and gold, are mechanically concentrated by currents due to their specific gravities. These concentrations are called placer deposits.

What role do chemically active fluids play in metamorphism?

Chemically active fluids can bring new atoms into the rock or take atoms out of the rock, thus altering the rock's composition.

Why are mineral bands in metamorphic rocks light and dark colored?

Dark minerals rich in iron and magnesium separate from light minerals rich in silica and aluminum.

Which of the following minerals does not form as a result of magmatic segregation?

Diamond

Which kind of stress (confining pressure or differential stress) is responsible for creating the texture visible in this rock?

Differential stress Submit

How do black smokers get their name?

Dissolved minerals are ejected from chimneys and rapidly precipitate out of solution, creating a dark color.

What is a fossil?

Evidence of past life that can include skeletal as well as trace material

An igneous dike cuts through limestone, but not through the overlying sandstone. Which of the following statements is most accurate?

First, the limestone was laid down, then intruded by the igneous dike, and lastly the sandstone was deposited.

Which of the following describes the principle of original horizontality?

Folded sedimentary layers were originally laid down flat and later deformed.

What are the two main categories of metamorphic texture?

Foliated and nonfoliated

Which of the following best describes the principle of faunal succession?

Fossil organisms succeed one another in a specific and identifiable order.

What is the principle of "fossil succession"?

Fossil organisms succeed one another upward through rock layers in a definite and determinable order; therefore, any time period can be recognized by its fossil content.

What is the principle of fossil succession?

Fossil organisms succeed one another upward through rock layers in a definite and determinable order; therefore, any time period can be recognized by its fossil content.

Which of the following is an example of a trace fossil?

Gastroliths

List three economic materials that can be profitably extracted from placer deposits.

Gold, platinum, and tin

Which mineral resource is the main component for plaster and drywall?

Gypsum

Which of the following is a nonmetallic mineral resource that is used as a building material?

Gypsum

What is the most important factor driving metamorphism?

Heat

Which agent of metamorphism was primarily responsible for generating the rock in the image above?

Heat

Return to the Gigapan image. Closely examine the rocks for evidence of metamorphic agents. Determine the metamorphic agent(s), or main metamorphic process(es), of the dark metamorphic rock in the Gigapan image.

Heating and pressure in one main direction

How can contact metamorphism result in the deposition of ore deposits?

Hot fluids in contact with the country rock can result in chemical reactions that facilitate the migration of metallic ions

How can contact metamorphism result in the deposition of ore deposits?

Hot fluids in contact with the country rock can result in chemical reactions that facilitate the migration of metallic ions.

________ deposits such as gold and silver are generated from hot, ion-rich fluids.

Hydrothermal

__________ naturally concentrate(s) the less common elements of Earth's crust.

Hydrothermal solutions

How do diamonds form?

In ultramafic rocks called kimberlites

Distinguish between building materials and industrial minerals.

Industrial minerals are less abundant than building minerals; their deposits are far more restricted in distribution and extent, and they need to undergo a considerable amount of processing before the desired material can be used. On the other hand, building materials are more abundant than industrial minerals; they generally require less transport and less processing before use.

________ is a high-pressure ultramafic rock, often containing diamonds, that is carried to the surface in tapered volcanic pipes.

Kimberlite

________ is a high-pressure ultramafic rock, often containing diamonds, which is carried to the surface in tapered volcanic pipes.

Kimberlite

Primates have existed for approximately 1.3 percent of geologic time. The Phanerozoic eon, the present Eon, is 10.84 percent of geologic time. Life has existed on Earth approximately 76 percent of geologic time. Label the accompanying geologic time scale for when these historical events began. The labels that you will place on the scale include events in Earth's history and number of years (in millions of years) before present. Round the age of Earth to 5 billion years. Note that the years indicated are millions of years ago. For example, the most recent age on the chart is 65.5 million (65,500,000) years ago.

Life began about 4 billion years ago, around the start of the Eoarchean era. Primates have existed for only a flicker of time, about 65.5 million years, compared to the age of Earth. The Phanerozoic eon began about 542 million years ago.

How do ore deposits relate to contact metamorphism?

Materials susceptible to contact metamorphism, such as limestone, experience chemical reactions as the hot fluids from the igneous rock move through the limestone. This often results in the creation of metal-rich deposits surrounding the plutons that have invaded the limestone.

In what era is the Jurassic period?

Mesozoic

Which of the following phrases describes brittle deformation?

Metamorphic rocks are broken. It occurs at cold temperatures.

________ is the process by which a rock changes form or mineral content as a result of environmental changes such as heat and pressure.

Metamorphism

How can a rock change during metamorphism?

Metamorphism can change the mineralogy, texture, and/or chemical composition of a rock.

Which of the following statements regarding radioactive decay is true?

More daughter products accumulate over time.

Which scientist is credited with developing the law of superposition?

Nicholas Steno

Could metamorphic rocks reach the surface of a planet without rock-uplifting processes?

No, metamorphic rocks must be uplifted and exposed by erosion.

What is the texture of this rock?

Nonfoliated

A ________ is an economically important material that cannot be replenished in a reasonable time frame, so once it has been consumed, there will not be any more.

Nonrenewable resource

Name the two types of "geologic time": (each is a single-word, separate them with a single space only)

Numerical, and Relative

Which of the following would make the best index fossil: olenellus (522-510 million years ago), flexicalymene (~490-418 million years ago), and phacops (~418-360 million years ago).

Olenellus

________ is the scientific study of fossils.

Paleontology

What happens during radioactive decay?

Parent isotopes turn into daughter isotopes.

Petrified wood is an example of what type of fossilization?

Permineralization

________ is a term used to define 88% of Earth's history prior to the start of the Paleozoic era.

Precambrian

How are metamorphic rocks formed?

Preexisting rock is altered through heat and pressure.

Which of the following best describes the conditions of contact metamorphism?

Pressures are fairly low, the rock is in the upper part of the crust, and heat is supplied from a nearby magma body.

What is the definition of relative dating?

Putting events in order from first to last

How might pyrite play a role in creating an ore deposit?

Pyrite chemically weathers into sulfuric acid, which allows percolating water to dissolve ore metals. The dissolved metals migrate downward through the primary ore body until they are precipitated.

Which two conditions are the most important in order for an organism to become fossilized?

Rapid burial and possession of hard parts

How is quartz sandstone metamorphosed into quartzite during contact metamorphism?

Sand grains are fused together because of high temperatures

Which of the following would describe a placer deposit?

Sediments are segregated by running water, leading to areas of high concentration of useful minerals

Who is credited with the "principle of fossil (faunal) succession"? He was the English engineer and canal builder who observed that sedimentary strata in widely separated areas could be identified by their distinctive fossil assemblages. (LAST name only, please)

Smith

What is the definition of a placer deposit?

Sorting of particles by a water current according to a material's specific gravity

The figure below shows a hypothetical orientation of slaty cleavage. Place the thick arrows in the direction of maximum stress and the thin arrows in the direction of minimum stress. If stress is equal in all directions, place all thin arrows.Drag the appropriate labels to their respective targets. Labels may be used only once.

Starting from the top and moving counterclockwise:Thick Arrow Pointing Down and RightThin Arrow Pointing Up and RightThick Arrow Pointing Up and LeftThink Arrow Pointing Down and Left

Who is the Danish anatomist and geologist that is credited with the principle of superposition? (last name only)

Steno

Which of the following is an example of a relative date?

The Silurian period came before the Devonian period.

This Gigapan image shows a dark metamorphic rock in contact with a lighter igneous rock (granite). Review the statements below, and determine which are correct about the dark metamorphic rock on the left in the Gigapan image.

The metamorphic rock shows foliation.

What is the best definition of fossil range?

The period of time when an organism first and last appears in the sedimentary record.

How is the geologic time scale related to the fossil record?

The periods of the time scale were constructed based on ranges of fossil organisms

Which of the following is a characteristic of a mineral deposit?

The profitability of a deposit can change if the market price of that metal changes.

Two containers hold the same radioactive isotope. Container A contains 1000 atoms, and container B contains 500 atoms. Which of the following statements about containers A and B is true?

The rate of decay of atoms (half-life) in container B is the same as the rate of decay of atoms (half-life) in container A.

What is the definition of a half-life?

The time it takes for half of the parent isotope to decay to the daughter

Which of the following statements describes a mylonite?

They are formed through ductile deformation.

________ occurs when weathering concentrates minor amounts of metals scattered through unweathered rock into economically valuable concentrations.

Secondary enrichment

Match the parent isotope with the correct daughter isotope.

Thorium-lead, rubidium-strontium, potassium-argon, uranium-lead, Carbon-Nitrogen

A worm burrow is an example of which type of fossilization?

Trace fossil

Radioactive decay in mineral shows that two half-lives have elapsed, giving an age of approximately 1.4 billion years. Using the table in the video as a reference, what is the correct radioactive parent and stable daughter isotope pair?

U235, Pb207

How is confining pressure different from differential stress?

When a rock is under confining pressure, all of the forces are applied to the rock equally in all directions. However, pressure applied to a rock by differential stress is greater in a single direction than in all of the other directions.

________ was the English engineer and canal builder who observed that sedimentary strata in widely separated areas could be identified by their distinctive fossil assemblages.

William Smith

What does the term unconformity mean?

a missing rock layer in a sequence that represents a period of erosion or nondeposition

What is a metamorphic aureole?

a ring of metamorphic rocks adjacent to an igneous intrusion

Which of the following includes all common types of radioactive decay?

alpha particle emission, beta particle emission, electron capture

If a sample of rock is radiometrically dated and it is later discovered that some of the parent isotope may have been removed from the sample by weathering, the absolute age date that was obtained will be:

artificially old

What is foliation?

banding in metamorphic rocks that results from the reorientation of minerals

Aluminum laterite is also known as the mineral ________.

bauxite

Where do most metamorphic rocks form?

between a few and many kilometers beneath Earth's surface

Graphite deposits typically form geologically ________.

by regional metamorphism of organic-rich, black shales

Which substance listed below could serve as either a building mineral or an industrial mineral?

calcite

Inclusions

chunks of weathered rock are older than the rock they are contained in.

What does quarts sand make?

concrete

When rocks are __________, several adjacent layers were deposited without interruption.

conformable

Which type of plate boundary is associated with regional metamorphism?

continental-continental convergent boundary

Nonmetallic minerals used for abrasives include ________.

corundum and garnet

What is the source of natural carbon-14?

cosmic ray collisions and nuclear changes involving atmospheric nitrogen

Which of these IS NOT a required criteria for considering something a resource;

currently exploitable

Following the deposition of a sequence of sedimentary rocks, which event is the first to occur to produce an angular unconformity?

deformation

What are the four agents that drive metamorphism?

directional stress, pressure, heat, and chemically active fluids

A(n) __________ exhibits sedimentary layers that are parallel to each other above and below an erosive surface.

disconformity

Which processes result in mineral flattening during metamorphism?

dissolution followed by crystallization

In order of longest to shortest, what are the four basic units that make up the geologic time scale?

eon, era, period, epoch

Which of the following is a common feature that all unconformities exhibit?

erosive surface

Cross-Cutting Relationships

faults, fractures are younger than the rocks they cut through.

Which mineral resources are associated with magmatic differentiation?

feldspar, which can form as a pegmatite deposit platinum, which can form by the differentiation of basaltic magma

Carbonization

fine sediment encases plant remains, leaving behind an organic residue

What is the name for minerals of little value that are associated with the ore minerals? (single-word expected)

gangue

What would you call a granite that has undergone metamorphism and now exhibits foliation?

gneiss

Which of the following is a metamorphic rock?

gneiss

Which of the following materials the highest concentration factor?

gold

Detrital grains of ________ are not likely to be concentrated in placer deposits.

gypsum

Using the geologic cross section below, put the rock layers in order from oldest to youngest. Use the blanks to the right of the figure for your answers.

h,m,x,p,c,z,t

Which of the following factors describes the conditions at a zone where contact metamorphism is occurring?

high temperature, low pressure

Cast and mold

hollows left by dissolved fossils are filled with mineral matter

A sandstone contains inclusions of metamorphic rock. An igneous dike cuts both the sandstone and inclusions. List the rocks from youngest to oldest.

igneous dike, sandstone, metamorphic rock

Trace Fossil

indirect evidence of fossil life (i.e. tracks, burrows)

Diamonds are typically found in ___.

kimberlite pipes

Pegmatites are igneous rocks with __________ crystals, formed from a __________.

large; wet magma

Deeply weathered tropical soils that develop in warm, rainy climates are called ________.

laterites

At a convergent boundary, which of the following would show the orientation of slaty cleavage?

lines up and down,The maximum stress is being applied from the sides. Slaty cleavage is perpendicular to the maximum stress applied, so at convergent boundaries, slaty cleavage runs vertically.

Which two rock types would you expect to see sitting next to each other after a very long period characterized by only uplift and erosion?

metamorphic and sedimentary rocks

Where is hydrothermal metamorphism common?

mid-ocean ridges

Why do bands of minerals form when rocks are put under normal stress?

minerals dissolve, atoms migrate to new locations, and minerals reform

Unconformities

missing time.

Which of the following best describes confining pressure and the location in which it occurs?

moderate pressures at shallow depths

In the following rock sequence, how much erosion might have occurred between rock layer A and rock layer B?

none or only a very small amount (Time does not equate to erosion.)

In the list below, indicate which of the environments fossilization is likely to occur in. Note that fossils contain organic matter.

ocean floor, swamp, floodplain

What materials are best dated with carbon-14?

organic materials

Permineralization

organic pores are filled with precipitated minerals

Which of the following characteristics is the most desirable for constraining the relative age of rocks?

organisms with overlapping ranges and geologically short lifespans

How will minerals orient when a rock is put under shear stress?

parallel to the direction of the shear stress

In radioactive decay, an unstable ________ isotope will decay into a stable ________ isotope.

parent; daughter

How will foliation in continental metamorphic rocks formed during subduction be oriented?

perpendicular to the direction of plate movement

How will minerals orient when a rock is put under normal stress?

perpendicular to the direction of the greatest stress

The California Gold Rush began because gold was found in a ____.

placer deposit

An undeformed sequence of sedimentary rocks is exposed in a large river canyon. Which two principles would be demonstrated by the rocks?

principles of superposition and lateral continuity

What does cement require?

quarts sand

What special conditions are necessary for presevation of the vast majority of fossils? (select ALL that apply)

rapid burial, hard parts

Lateral Continuity

rocks extend in all directions until they reach the edge of a basin or pinch out.

Which organism from the video is the least useful for relative dating?

scallop

Original horizontality

sedimentary layers/lava flows are deposited in flat layers.

Which of the following metamorphic rocks would form as a result of shale undergoing low-grade regional metamorphism?

slate

Do metamorphic rocks look like the preexisting rock from which they form?

sometimes, but not always

What is the scientific definition of half-life?

the amount of time over which the number of parent isotopes decreases by half

What is secondary enrichment?

the creation of important mineral deposits by concentrating minor amounts of metals that are scattered through unweathered rock into economically valuable concentrations

Superposition

the oldest is on the bottom, the youngest on top.

What is rock texture?

the way a rock looks

How do metamorphic rocks reach Earth's surface?

through removal of overlying rocks

A mineral deposit may lose its profitability due to economic changes such as rising production costs and stock market volatility.

true

When minerals precipitate in a fracture, they are referred to as __________.

vein deposits

Which of the following best describes the water transport path before exiting through a black smoker at the seafloor?

water circulates through the ocean crust, causing it to heat up and become saturated with dissolved minerals

The sedimentary layers above an erosive surface are __________ relative to all rocks present below the surface.

younger

Which of the following is an accurate description of a nonconformity?

younger sedimentary strata overlie uplifted and weathered igneous or metamorphic rocks

What is the ratio of parent atoms to daughter atoms after three half-lives?

1:7

A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many atoms of the radioactive isotope will be in the container after 3 months?

25 atoms

What remains after a sample undergoes two half-lives?

25 percent of the sample is composed of parent atoms, and 75 percent of the sample is composed of daughter atoms.

Quartz sand

2nd more used reasons in the world; most use other than water

Which of the following is a temperature associated with metamorphism?

400 degrees Celsius

If one half-life has lapsed, what is the radioactive parent to stable daughter isotope ratio?

50:50