Geology Exam #3

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What set of processes is written in order of increasing temperature?

Sedimentation, Diagenesis and Metamorphism.

In what sedimentary environments would gravel most likely be deposited?

Alluvial.

In what environments would gravel be least likely to be deposited?

Deep-sea.

What sedimentary environments is dominated by river currents and waves?

Deltaic.

In what environments are siliceous sediments deposited?

Deep-sea.

What is not a sedimentary structure?

Vesicles.

What is the term for the process by which organisms burrow through muds and disrupt the sedimentary bedding?

Bioturbation.

What is the approximate temperature of sediment that is buried to a depth of 4 km?

120 degrees Celsius.

What process occurs during lithification?

Recrystallization of unstable minerals, Compaction and Cementation.

Burial of sediments results in __________.

Increasing pressure and Increasing temperature.

What is the porosity of newly deposited mud?

Greater than 50%.

What term describes the alteration of sediments to sedimentary rocks after deposition?

Diagenesis.

True or False: Cementation and compaction both decrease porosity.

True.

Write in order decreasing particle size.

Conglomerate, sandstone, siltstone.

What is an example of a clastic sedimentary rock?

Shale.

What rocks are composed of clay-sized clastic sediment?

Shale.

What fine-grained sedimentary rocks is clastic and displays blocky fracture and little or no bedding?

Mudstone.

A clastic sedimentary rock composed of medium-grained (1 mm across) particles is called a ______.

Sandstone.

What sedimentary rock groups are most abundant?

Siltstones, mudstones, and shales.

In which sedimentary rocks would it be easiest to determine the type of rocks from which the sediment was derived?

Conglomerates.

What types of sandstones is most likely to form by the rapid mechanical weathering of a granite?

Arkose.

What type of sandstone contains abundant rock fragments?

Lithic sandstone.

What type of sediments are accumulations of solid fragments produced by weathering?

Clastic sediments.

What kinds of sandstone is the most poorly sorted?

Arkose.

The most abundant chemical/biochemical sedimentary rocks are ______.

Carbonates.

Most of the carbonate sediments of the ocean are derived from _________.

Foramnifera.

What is the most abundant non-clastic sediment?

Carbonate.

The Bahamas are an example of a(n) __________.

Carbonate platform.

Where do atolls form?

On subsiding volcanic islands.

What mineral does not precipitate directly from seawater?

Dolomite.

The conversion of limestone to dolostone involves the replacement of calcium ions with __________.

Magnesium ions.

What is not a clastic sedimentary environment?

Evaporite.

What mineral is least likely to occur in a marine evaporite environment?

Quartz.

What mineral would be most concentrated at a site containing heavily weathered sediments?

Quartz.

What is deposited only by non-biological, chemical precipitation?

Halite.

What minerals precipitate directly from water in evaporite deposits?

Gypsum.

What sedimentary rock is composed of biochemically precipitated silica?

Chert.

Oil and gas are found mainly in ___________.

Sandston and limestone.

What process is not an important cause of subsidence during the development of a sedimentary basin?

Erosion of sediments.

Coral reefs are generally limited to waters approximately ________ deep or less.

20m.

What type of sedimentary basins is most likely to develop where two plates pull apart?

Rift basins.

Sedimentary processes take place ____________.

At or near the Earth's surface.

Physical weathering involves the breakdown of rocks at the Earth's surface through ____.

Mechanical processes.

The type of weathering whereby rocks may be dissolved is called _______.

Chemical weathering.

How fast are moderate-strength river currents that carry and deposit sand?

20 to 50 cm/s.

The study of sedimentary rocks helps geoscientists determine ______.

Ancient ocean environments, former plate tectonic events, and history of climate change.

The three main types of sediment are:

Siliciclastic, biological, chemical.

Abrasion of sediment particles results in what?

They become smaller and more rounded.

Sedimentary basins are formed by a process called _________.

Subsidence.

The type of sedimentary basin that forms as a result of one tectonic plate overriding another, causing the plate to bend downward, is called a _______.

Flexural basin.

At what temperature does organic matter begin to convert to oil and gas?

90 degrees Celsius.

Coal is produced from the diagenesis of ______.

Swamp vegetation.

True or False: Smaller particles settle faster than larger particles.

False.

The tendency for variations in current velocity to segregate sediments on the basis of particle size is called ______.

Sorting.

The salinity of the ocean ________.

Remains approximately constant.

What environment is an example of a shoreline environment?

Deltaic.

Marble is a metamorphic rock that forms from __________.

Limestone.

What is metasomatism?

A change in the bulk composition of a rock during metamorphism.

What is the primary source of the carbon dioxide in metamorphic fluids?

Sedimentary carbonates.

What type of metamorphism is caused by high temperature and high pressure imposed over a large volume of crust?

Regional.

What type of metamorphism is caused by igneous intrusions?

Contact Metamorphism.

At what depth does low-grade metamorphism begin?

6-10km.

Where does seafloor metamorphism take place?

Divergent plate boundaries.

What is the relation between metamorphic foliation and sedimentary bedding?

There is no general angular relationship between sedimentary bedding and metamorphic foliation.

The parallel alignment of mica in a metamorphic rock is an example of ______.

Foliation.

What type of metamorphic rock was once used to make blackboards because of its ability to split easily into thin sheets along smooth, parallel surfaces?

Slate.

What rock represents the highest metamorphic grade?

Gneiss.

What tectonic settings will be coolest at 30-km depth?

Stable continental lithosphere.

What is not used to classify foliated rocks?

The texture of the parent rock.

What tectonic settings may be characterized by regional, high-pressure, and ultra-high-pressure metamorphism?

Convergent plate boundaries.

True or False: With increasing metamorphism, the grain size of the rock gets smaller.

False.

What sequences describes the metamorphic changes in a shale with increasing metamorphic grade?

Slate-Schist-Gneiss.

Light-colored rocks with coarse bands of segregated light and dark minerals are called ______.

Gneisses.

What metamorphic rocks is incorrectly paired with its parent rock?

Quartzite-Granite.

What metamorphic rocks is always foliated?

Schists.

What rock has granular texture?

Hornfels.

What metamorphic rocks forms from mafic volcanic rocks?

Greenstone.

A non-foliated contact metamorphic rock is called a ______.

Hornfels.

What minerals is diagnostic of metamorphism?

Staurolite.

Granoblastic metamorphic rocks generally contain minerals that are _______ in shape.

Equant.

What metamorphic rocks cannot form from a shale?

Marble.

What type of metamorphic rock has undergone partial melting?

Migmatite.

What rocks can be considered gradational between an igneous and a metamorphic rock?

Migmatite.

What metamorphic minerals commonly forms porphyroblasts?

Garnet.

What is a porphyroblast?

A relatively large metamorphic mineral.

What rocks represents the highest grade of metamorphosed mafic volcanic rocks?

Granulite.

What metamorphic facies occurs at temperatures of 400°C and pressures of 6 kilobars?

Greenschist.

What is the most likely parent rock of a metamorphic rock containing muscovite, biotite, garnet, and quartz?

Shale.

What metamorphic facies represents the highest temperature?

Granulite.

What is the pressure on a rock at 15-km depth in the Earth's crust?

Approximately 4000 times atmospheric pressure.

Under what conditions does zeolite-facies metamorphism occur?

Relatively low pressure and low temperature.

Which mineral is commonly used to determine a metamorphic P-T path?

Garnet.

The prograde part of a metamorphic P-T path occurs during __________.

Burial and heating.

Mélanges and blueschists are characteristic of which tectonic setting?

Subduction zones.

What metamorphic rocks form in the forearc of a subduction zone?

Blueschist.

What metamorphic rock could also be considered a transitional rock between igneous and metamorphic?

Migmatite.

Metamorphic mineral assemblages that can be used as pressure gauges are referred to as _________.

Geobarometers.

What kind of metamorphism would you expect to see in the rocks at a meteorite impact site?

Shock.

Eclogite rocks form during ___________ metamorphism.

Ultra-high pressure.

The parent rock of quartzite is _______.

Sandstone.

A geothermometer is ___________.

A mineral assemblage that reveals the maximum temperature attained by a rock.

The parent rock of granofels is _________.

Shale, impure sandstone and granite.

A metamorphic rock that is described as porphyroblastic has _________.

Large crystals in a fine-grained matrix.

Different pressure-temperature zones within a belt of regionally metamorphosed rock are defined by the presence of _______.

Index minerals.

Epidote is a common metamorphic mineral found in ________.

Metamorphosed basalt.

What kind of metamorphism would you expect to find at a convergent plate margin?

Regional, high-pressure and contact.

The process whereby metamorphic rocks rise to the Earth's surface is called _______.

Exhumation.

The flow of metamorphic rocks back to the Earth's surface is controlled by tectonics and _________.

Erosion.

What is the average rate at which temperature increases with depth in the Earth's crust?

30 degrees C/km.

What processes will cause metamorphism?

An increase in pressure, interaction with hydrothermal fluids, and an increase in temperature.

During metamorphism, changes in the bulk composition of a rock occur primarily as a result of __________.

Reaction with hydrothermal fluids.

What is a general pressure in all directions, such as the pressure that the atmosphere exerts?

Confining pressure.

The hypothesis that explains the formation of the solar system is referred to as _____.

Nebular hypothesis.

Why is the Sun's mass decreasing with time?

Because the Sun's nuclear fusion consumes mass.

Under intense pressure and high temperature, hydrogen atoms combine to form helium. This process is called _____________.

Nuclear fusion.

According to the nebular hypothesis, the inner planets are dense and rocky because __________________.

The lighter gases were blown away by the Sun's radiation.

What caused dust and condensing material to accrete into planetesimals?

Gravitational attraction and collisions.

The four inner planets are ________________.

Small, rocky, and relatively lacking in volatile elements.

Nebulae are composed primarily of what elements?

Hydrogen and helium.

What are the outer planets?

Neptune, Uranus and Saturn.

The giant outer planets are composed mostly of ___________.

Hydrogen and helium.

What is the process by which an originally homogeneous Earth developed a dense core and a light crust?

Differentiation.

The heat that caused melting in the Earth's early history was supplied from which of the following events or causes?

A large impact event and radioactivity.

The oldest terrestrial material found on the Earth is approximately _______ old.

4.4 billion years.

True or False: The Earth and Moon are approximately the same age.

True.

The effects of the collision of a large Mars-sized body with the Earth about 4.5 Ga is proposed to have caused __________.

A magma ocean to form at the Earth's surface, an increase in the Earth's speed of rotation and the Earth's spin axis to tilt.

What planet is not geologically active?

Mercury.

The evidence that Mars once had water includes _________.

Dry river beds and valleys.

True or False: Mars has liquid water and a corrosive atmosphere.

False.

What solar system bodies is least likely to have water ice on its surface?

Venus.

The Earth exchanges __________ with the rest of the cosmos.

Energy and mass.

Solar energy energizes all of the following major components of the Earth system except the ____________.

Lithosphere.

What powers the Earth's external heat engine?

Solar energy.

What powers the Earth's internal heat engine?

Radioactivity and heat trapped during the formation of the Earth.

The asteroid belt lies between which two planets?

Mars and Jupiter.

Because of Mercury's proximity to the Sun, the daytime temperatures at its surface are approximately ____°C.

470.

What planet is surrounded by a hot atmosphere comprised of carbon dioxide and clouds of sulfuric acid?

Venus.

Which planet is closest in size to the Earth?

Venus.

The atmosphere of Mars is comprised of ______.

Carbon dioxide.

The time in early solar system history when there were numerous crater-forming impacts is known as the time of _______.

Heavy Bombardment.

The light-colored regions visible on the Moon's surface correspond to the ________.

Lunar highlands.

The dark regions visible on the Moon's surface correspond to the what?

Lunar maria.

What kinds of rocks are found in the lunar maria?

Basalt.

Which planet is also known as the volcanic planet?

Venus.

Because of the dense foggy atmosphere that surrounds Venus, its surface was explored using _______technology.

Radar.

Which planet had shield volcanoes?

Earth, Mars and Venus.

Venus's unique surface is thought to have formed through a process of vigorous mantle convection, volcanic activity, and crustal stretching referred to as _______.

Flake tectonics.

The tallest volcano in the solar system is found on _________.

Mars.

Mars is also called the Red Planet because of _________.

The abundance of iron oxide minerals on the surface gives it a red appearance.

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