Physical Geology Lecture Exam 2

Shock metamorphism is associated with: a. High P/T b. Intermediate P/T c. Low P/T d. Ultrahigh P/High T

D

The Grand Canyon carved out by the Colorado River exposes: a. Sedimentary rocks b. Igneous rocks c. Metamorphic rocks d. All of them

D

Mylonites

Dynamic metamorphism

List 3 Tectonic and/or Mantle Processes that trigger decompression melting:

1. Continental Rift Valleys: -P is decreased as continental crust is under extension by plate tectonic forces (pulled apart) 2. Mid-ocean ridges -P is decreased as new, thin, oceanic crust is produced and is being pushed away (seafloor spreading) by ridge-push forces 3. Mantle Plumes -P is decreased as plumes move up through the mantle

List the 4 tectonic settings where igneous activity occurs:

1. Subduction Zones -Produce volcanic arcs on Earth's surface (conv. boundaries where melt is present, FIM) 2. Mid-ocean ridges -Oceanic crust is moving apart (div. boundaries, DM) 3. Continental Rifts -Continental crust is thinned (DM) 4. Hot Spots -Intrude the Earth's surface through a plate (no boundaries involved, DM)

A coarse-grained magmatic igneous rock with 65% SiO2 and containing minerals like quartz, K-feldspar may be called: a) Granite b) Gabbro c) Diorite d) Basalt

A

A low-grade metamorphic rock containing chlorite-biotite-muscovite is subjected to higher P/T conditions. Which of the following minerals will be replaced first during neocrystallization? a. Chlorite b. Biotite c. Muscovite d. All of them at the same time

A

A metamorphic rock contains the minerals coesite and diamond. What can you infer about the P/T conditions of the rock? a. Very high P b. High P, Low T c. Low P, High T d. Any of the above

A

A phaneritic texture is one in which: a) Individual crystals can be seen with the naked eye b) Individual crystals cannot be seen with the naked eye c) Individual crystals are a mix of coarse and fine-grained crystals d) Pores are abundant

A

All intrusive igneous rocks have: a) Phaneritic texture b) Porphyritic texture c) Glassy texture d) Vesicular texture

A

Alluvial fan is a type of depositional environment where the following happens: a. A change in river flow velocity b. A change in slope of the land c. Deposition of sediments eroded from mountain tops d. All of them

A

Bowen's Reaction Series: a) Shows that minerals in a cooling magma crystallize in a predictable order b) Shows that as magma crystallizes, the remaining melt is depleted in silica c) Explains why some igneous rocks phaneritic, and others aphanitic

A

Dikes and sills are: a) High-angle and low-angle igneous intrusions b) High-angle and low-angle felsic intrusions c) Low-angle and high-angle igneous intrusions d) Low angle and high-angle felsic intrusions

A

During metamorphism in a compressive stress field, how does the minerals acquire preferred orientation? a. Mineral long axes align normal to the direction of maximum compressive stress b. Mineral long axes align parallel to the direction of maximum compressive stress c. Mineral long axes are oblique to the direction of maximum compressive stress d. Mineral long axes may align normal or parallel depending on direction of stress

A

How would you get a gneiss from phyllite? a. Reheating b. Melting c. Weathering d. All of them

A

How would you get a metamorphic rock from an igneous rock? a. Reheating b. Melting c. Weathering d. All of them

A

Metamorphic grade implies: a. P, T conditions of a rock environment b. T conditions of a rock environment c. P, T, Stress conditions of a rock environment d. P, T, Stress, Fluids conditions of a rock environment

A

Quartzite and marble lack foliation because they have: a. Equant mineral grains: -Roughly equal in all dimensions b. Inequant mineral grains: -Dimensions are not the same

A

Regional metamorphism is typical of: a. Mountain belts b. Continental rifts c. Accretionary prisms d. Volcanoes

A

Sediments eroded from the Putnam County by the Caney Fork river may be deposited in: a. Gulf of Mexico b. Pacific Ocean off the Californian coast c. Atlantic Ocean off the coast of North Carolina d. All of the them

A

The dominant rock-type in coral reefs is: a. Limestone b. Sandstone c. Shale d. Conglomerate

A

Two magma chambers of similar size are undergoing crystallization. Chamber A is tabular. Chamber B is spherical. Which chamber cools faster? Note: Tabular flows/chambers cool faster than spherical chambers.

A

What kind of melting do you expect just under a mid-ocean ridge? a. Decompression melting b. Heat-transfer melting c. Flux-induced melting

A

Which is the correct sequence for increasing grain size inside the Earth? a. Slate-phyllite-schist-gneiss b. Gneiss-schist-phyllite-slate c. Slate-schist-phyllite-gneiss d. Gneiss-phyllite-schist-slate

A

Which of the following is a dominant mineral in limestone? a. Calcite b. Quartz c. Olivine d. K-feldspar

A

Which of the following melt compositions do you expect to travel long distances? a) Basalt melts b) Granitic melts c) Rhyolite melts d) Andesite melts

A

Which of the following metamorphic rocks have visible mineral grains? a. Schist b. Phyllite c. Slate d. Shale

A

Why does molten rock move upward through the Earth's mantle? a) Molten rock is less dense than the surrounding solid rocks b) Molten rock is more dense than the surrounding solid rocks c) Molten rock is chemically more homogenous than the surrounding solid rocks d) Molten rock is chemically less homogenous than the surrounding solid rocks

A

With increasing P, inside the Earth: a. High density minerals are formed. b. Low density minerals are formed. c. Pressure inside Earth does not influence which minerals will form at depths.

A

Which of the following rocks contain banded foliations? Check all options that apply. a. Gneiss b. Migmatite c. Schist d. Slate

A and B

A conglomerate sample consists of well-rounded clasts of granite, angular clasts of micaschist, and individual mineral fragments derived from granite and mica-schist. What can you infer about the source region of the sandstone? Check all options that apply. a. The basin where sandstone was deposited received sediments from both igneous and metamorphic terrains b. Igneous terrain was closer to the source than the metamorphic terrain c. Metamorphic terrain was closer to the source than the igneous terrain d. The combined source region dominant mineralogy (i.e., considering both the terrains together) is quartz, feldspar, biotite, muscovite

A, B, and D

A metamorphic rock-specimen contains the minerals muscovite and biotite but no chlorite. What can you infer about the P/T conditions where the rock formed? a. Low P/T b. Intermediate P/T c. High P/T d. Low T/High P

B

A small stream in an arid region which is experiencing severe droughts for a few years continuously is expected to best preserve the following sedimentary structure: a. Ripple marks b. Mudcracks c. Cross beddings d. Dunes

B

An aphanitic texture is one in which: a) Individual crystals can be seen with the naked eye b) Individual crystals cannot be seen with the naked eye c) Individual crystals are a mix of coarse and fine-grained crystals d) Pores are abundant

B

An igneous rock containing <45% SiO2 is called: a. Mafic rock b. Ultramafic rock c. Felsic rock d. Intermediate rock

B

As a mantle rock moves from a depth of 300 km to 150 km, what happens? a. It heats up b. It begins to melt via decompression c. It stays at the same depth inside the Earth d. It does not change its physical state because temperature has not changed

B

Burial metamorphism is common in: a. Volcanoes b. Sedimentary basins c. Deeper parts of subduction zones d. All of them

B

Cross beds indicate: a. Tilt of sedimentary beds b. Average flow direction c. Drought conditions

B

How would you get an igneous rock from another igneous rock? a. Reheating b. Melting c. Weathering d. All of them

B

In most types of metamorphism, bulk element composition of parent rock is: a. Different from that of the parent rock b. Same as that of the parent rock

B

Porphyritic rocks are named for the size of: a) Phenocrysts b) Groundmass grains

B

Principle of uniformitarianism states that: a. Younger rocks are deposited on top of older rocks b. Geologic processes occurring now happened throughout Earth's history c. Sedimentary rocks are deposited in layers

B

Ripple marks on a sandstone indicate: a. Drought conditions b. Current flow conditions c. Flooding conditions

B

Vesicles in vesicular textures are remnants of: a) Melt passages in an igneous rock b) Volatile passages in an igneous rock c) Passages through which crystals settle out from an igneous melt

B

What does a black shale tell about its depositional environment? a. Oxidizing atmospheric conditions b. Reducing marine conditions c. Alternate oxidizing and reducing d. None of them

B

What kind of igneous rocks do you expect at mid-ocean ridges? a) Felsic fine-grained b) Mafic fine-grained c) Intermediate fine-grained d) Felsic coarse-grained

B

What would you call a very-fine clastic grained sedimentary rock with clay minerals? a. Sandstone b. Shale c. Conglomerate d. Rock salt

B

Which of the following is a biochemical sedimentary rock? a. Rock salt b. Chalk c. Rock gypsum d. Coal

B

Which of the following is a chemical sedimentary rock? a. Fossiliferous Limestone b. Oolitic Limestone c. Micritic Limestone d. All of them

B

Which of the following is a dominant mineral in sandstone? a. Calcite b. Quartz c. Olivine d. Plagioclase feldspar

B

Which of the following minerals is found in impact craters only? a. Coesite b. Stishovite c. Rose Quartz d. All of them

B

Which of the following pairs of minerals are part of the continuous reaction series in Bowen's Reaction Series? a) Pyroxene and Amphibole b) Ca-rich plagioclase and Na-rich plagioclase c) Pyroxene and Olivine d) Olivine and Ca-plagioclase

B

Which of the following rocks is not derived from an igneous rock melt? a. Granite b. Tuff c. Basalt d. Obsidian e. Porphyritic andesite

B

Would you expect olivine as a mineral fragment in the sandstone? a. Yes b. No c. Maybe (under specific circumstances)

B

A magma that is rich in volatiles is called: a) Rich magma b) Dry magma c) Wet magma d) Volatile-rich magma

C

A porphyritic texture is one in which: a) Individual crystals can be seen with the naked eye b) Individual crystals cannot be seen with the naked eye c) Individual crystals are a mix of coarse and fine-grained crystals d) Pores are abundant

C

A sandstone sample A has subangular sand grains, while a sandstone sample B has rounded sand grains. Which of the following statements are true? a. Sample B traveled less distance than Sample A b. Sample B received sediments from two source regions while sample A received from one c. Sample B traveled more distance than Sample A d. Sample B received sediments from one source region while sample A received from two

C

Arrange in correct order the set of processes leading to a clastic rock formation. a. Erosion-Weathering-Deposition-Cementation-Compaction-Burial b. Weathering-Erosion-Deposition-Compaction-Burial-Cementation c. Weathering-Erosion-Deposition-Burial-Compaction-Cementation d. Erosion-Weathering-Deposition-Burial-Compaction-Cementation

C

Chemical alteration of ocean floor basalts is an example of: a. Burial Metamorphism b. Dynamic Metamorphism c. Hydrothermal Metamorphism d. Contact Metamorphism

C

Composition of the earth's mantle is: a) Felsic b) Intermediate c) Mafic to ultramafic

C

Flood basalts are characteristic of: a) Subduction Zones b) Mid-ocean Ridges c) LIPs d) All of them

C

How would you get a conglomerate from a granite? a. Higher P/T b. Melting c. Weathering d. All of them

C

Intra-plate volcanism is seen at: a) Subduction zones b) Mid-ocean ridges c) Hotspots d) All of these

C

LIP is: a) Large Intrusive Provinces b) Long Intrusive Provinces c) Large Igneous Provinces

C

Porphyritic textures indicate: a) Slow cooling b) Fast cooling c) Initial slow cooling and then fast cooling

C

What does sorting of a clastic sedimentary rock indicate? a. Distance of transport b. Degree of rounding c. Number of sources involved d. All of them

C

What is the dominant mineral composition of marble? a. Quartz b. Feldspar c. Calcite d. Halite

C

What is the primary factor that keeps the mantle rocks from melting at very high temperatures of ~3000 °C? a) Chemical composition of the rocks b) Crystal structure of the minerals in rocks c) Overburden pressure

C

What kind of melting do you expect at subduction zones? a. Decompression melting b. Heat-transfer melting c. Flux-induced melting

C

What kind of melting do you expect in a continental rift tectonic setting? a. Flux-induced melting b. Heat-transfer melting c. Decompression melting

C

When a sandstone is metamorphosed, it turns to: a. Schist b. Phyllite c. Quartzite d. Slate

C

Where would you expect a chemical sedimentary rock like rock salt to be deposited? a. Deep Marine basin b. Shallow Marine basin c. Beach d. Swamp

C

Which of the following arrangements represent a correct sequence of deposition away from the source (i.e. closest to farthest)? a. Shale-Breccia-Conglomerate-Sandstone b. Conglomerate-Breccia-Sandstone-Shale c. Breccia-Conglomerate-Sandstone-Shale d. Shale-Sandstone-Conglomerate-Breccia

C

Which of the following is a mixed rock? a. Gneiss b. Schist c. Migmatite d. Slate

C

Which of the following is a possible metamorphic temperature? a. 900 °C b. 90°C c. 450 °C d. 180 °C Note: Most metamorphism occurs between 300°C - 700°C

C

Which of the following melt compositions are arranged in the order of increasing viscosity? a. Ultramafic<Mafic<Felsic<Intermediate b. Mafic<Ultramafic<Intermediate<Felsic c. Ultramafic<Mafic<Intermediate<Felsic d. Felsic<Intermediate<Mafic<Ultramafic NOTE: Viscosity of magma/lava increases with increasing SiO2%

C

Which of the following melt compositions are arranged in the order of increasing volcanic explosivity? a. Ultramafic<Mafic<Felsic<Intermediate b. Mafic<Ultramafic<Intermediate<Felsic c. Ultramafic<Mafic<Intermediate<Felsic d. Felsic<Intermediate<Mafic<Ultramafic REMEMBER: Felsic eruptions are more explosive

C

Which of the following rocks can be ignited? a. Shale b. Sandstone c. Coal d. Limestone

C

Which of the following rocks is made up entirely of shells of marine organisms? a. Micritic Limestone b. Oolitic Limestone c. Coquina d. Fossiliferous Limestone

C

Which of the following tectonic processes cools rocks inside the Earth? a. Geothermal gradient b. Subduction c. Exhumation d. Burial

C

Name an organic sedimentary rock.

Coal

Give an example of a LIP in continental US

Columbia River Flood Basalts

Lithification involves: _____ and _____

Compaction; Cementation

A dike intrudes into: a) Igneous rock b) Sedimentary rock c) Metamorphic rock d) All of them

D

A vesicular texture is one in which: a) Individual crystals can be seen with the naked eye b) Individual crystals cannot be seen with the naked eye c) Individual crystals are a mix of coarse and fine-grained crystals d) Pores are abundant

D

All aphanitic textures are: a) Fine-grained b) Derived from lava c) Cooled faster d) All of these

D

All phaneritic textures are: a) Coarse-grained b) Derived from magma c) Cooled slowly d) All of these

D

During metamorphic recrystallization, there is a change in: a. Mineral composition of the protolith b. Grain-size of the protolith minerals c. Texture d. Both (b) and (c)

D

Extrusive igneous rock textures can be: a) Fragmental or glassy texture b) Glassy or aphanitic texture c) Phaneritic or aphanitic texture d) Aphanitic or glassy or fragmental texture

D

Felsic magma: a) Crystallizes at highest temperatures b) Has ~40% silica c) Forms dark-colored igneous rocks d) Is more viscous than mafic magma

D

Fragmental texture is formed from: a. Volcanic lava b. Volcanic ash c. Volcanic rock debris d. Both (b) and (c)

D

In a flux-induced melting, which of the following can act as flux? a) Water vapor b) Carbon-dioxide c) Sulphur dioxide d) All of them

D

Metamorphism implies: a. P, T conditions of a rock environment b. T conditions of a rock environment c. P, T, Stress conditions of a rock environment d. P, T, Stress, Fluids conditions of a rock environment

D

Pyroclastic flow occurs in: a) Felsic melts flows b) Mafic melt flows c) Extrusive settings d) Both (a) & (c)

D

The characteristic mineral for subduction zone metamorphism which imparts a blue hue to the subduction zone metamorphic rocks is: a. Muscovite b. Biotite c. Chlorite d. Glaucophane

D

The early Cambrian (~500 Ma) rocks in Labrador, Canada contain ancient coral reefs preserved in rocks. What can you infer about the paleo-geographic position of the Labrador region 500 million years ago? a. Labrador, Canada was at the same geographic location in the Arctic as it is today b. Labrador, Canada was a deep marine region close to the Equator c. Labrador, Canada was in between Tropic of Cancer and Arctic Circle d. Labrador, Canada was a shallow marine underwater region close to the Equator

D

Three sedimentary rocks layers A, B and C are arranged in layers with A at the bottom and C at the top. An igneous dike I has intruded the rock layer A but it did not intrude B and C. Which of the following statements about I is true? a. I is older than A b. I is younger than B but not younger than C c. I is older than B but younger than C d. I is older than both B and C

D

Three sedimentary rocks layers A, B and C are arranged in layers with A at the bottom and C at the top. An igneous dike I has intruded the rock layers A and B but it did not intrude C. Which of the following statements is true? a. C is younger than B and A b. A and B are older than I c. C is younger than I d. All of them

D

What would you call a rock that has pebble-size angular clasts? a. Sandstone b. Shale c. Conglomerate d. Breccia

D

Where would you expect coal to be deposited? a. Deep marine basin b. Shallow marine basin c. Coral reefs d. Swamps

D

Which is the correct sequence for increasing metamorphic grade inside the Earth? a. Gneiss-schist-phyllite-slate b. Slate-schist-phyllite-gneiss c. Gneiss-phyllite-schist-slate d. Slate-phyllite-schist-gneiss Note: Increasing T and P = increasing metamorphism = increased grade

D

Which of the following metamorphic rocks are coarse-grained? a. Quartzite b. Gneiss c. Schist d. All of them

D

Which of the following minerals crystallize via the discontinuous reaction series? a) Olivine b) Pyroxene c) Amphibole d) All of them

D

Which of the following processes can turn a sedimentary rock into a metamorphic rock? a. Contact metamorphism b. Subduction metamorphism c. Burial metamorphism d. All of the them

D

Which of the following rocks display a stunningly black glassy texture? a. Basalt b. Andesite c. Scoria d. Obsidian

D

Which of the following rocks have banded foliations? a. Granite b. Slate c. Schist d. Migmatite

D

Which of the following rocks may be a protolith of gneiss? a. Schist b. Shale c. Granite d. All of them

D

Which of the following rocks would you expect to react with acid? a. Micrite b. Fossiliferous Limestone c. Chalk d. All of them Note: all have calcite

D

Which of the following situations are impossible in nature? a. A granite rock with olivine b. A metamorphic rock with marine shell fragments c. A conglomerate containing volcanic glass clasts d. Both (a) and (b) e. All of (a), (b) and (c)

D

Which of the following statements are true about sedimentary formations? a. They are arranged in layers b. They are mappable c. They may contain sedimentary structures d. All of them

D

Which of the following words may be used to describe portions of rock with porphyritic texture? a) Aphanitic b) Phenocrysts c) Groundmass d) All of them

D

Mafic igneous rocks tend to have ___________-color shades.

Darker

Graphite in a metamorphic rock is stable up to a certain P/T condition. Imagine metamorphic rock containing graphite is subjected to more intense P/T conditions, such that the graphite becomes unstable at the new P/T conditions. What will be the resulting new mineral phase?

Diamond

What is the giant reef system along the coast of NE Australia known as?

Great Barrier Reef

Give an example of a location experiencing hotspot-induced volcanism?

Hawaii

Deeper parts of Subduction Zones

High P/High T metamorphism

Volcano Tops

High T/Low P metamorphism

The rock-type produced by contact metamorphism is called:

Hornfels

Hot rock melt on the Earth's surface is called:

Lava

Felsic igneous rocks tend to have __________ -color shades.

Lighter

What is the parent rock for marble?

Limestone (or dolostone)

Hot rock melt inside the Earth is called:

Magma

Accretionary Prism

Low T/High P metamorphism

Coarse-grained crystals in porphyritic textures are called ________________.

Phenocrysts

Another name for fragmental texture is ___________________ texture

Pyroclastic

Alternating red and black shales in a sedimentary sequence indicate that the deposition environment experienced:

Rise and fall of sea-level

Give an example of a place currently undergoing continental rifting

The East African Rift Valley

Two magma chambers of similar size are undergoing crystallization. Chamber X is 10 km below the Earth's surface. Chamber Y is 50 km below the Earth's surface. Which chamber cools slower? Note: Deeper chambers lose heat very slowly and take a longer amount of time to cool than shallower chambers

Y