Geology - Exam 2

Which of the following is a biochemical sedimentary rock?

Chalk

What kind of melting do you expect at subduction zones?

Flux-induced melting

With increasing P, inside the Earth:

High density minerals are formed

Dikes and sills are:

High-angle and low-angle igneous intrusions

Would you expect olivine as a mineral fragment in the sandstone?

No

What does sorting of a clastic sedimentary rock indicate?

Number of sources involved

What is the primary factor that keeps the mantle rocks from melting at very high temperatures of ~3000C?

Overburden pressure

Metamorphic grad implies:

P, T conditions of a rock environment

Metamorphism implies:

P, T, Stress, Fluids conditions of a rock environment

A vesicular texture is one in which:

Pores are abundant

Burial metamorphism is common is:

Sedimentary basins

The Grand Canyon carved out by the Colorado River exposes:

Sedimentary, igneous, and metamorphic rocks

What would you call a very-fine clastic grained sedimentary rock with clay minerals?

Shale

Bowen's Reaction Series:

Shows that minerals in a cooling magma crystallize in a predictable order

Which is the correct sequence for increasing grain size inside the Earth?

Slate-Phyllite-Schist-Gneiss

Which of the following is a possible metamorphic temperature?

480C

Alluvial fan is a type of depositional environment where the following happens:

A change in rive flow velocity, a change in slope of the land, and deposition of sediments eroded from mountain tops

Which of the following situations are impossible in nature?

A granite frock with olivine and a metamorphic rock with marine shell fragments

Which of the following metamorphic rocks are coarse-grained? (quartzite, gneiss, schist)

All of them

Which of the following processes can turn a sedimentary rock into a metamorphic rock? (contact, burial, or subduction)

All of them

Which of the following rocks may be a protolith of gneiss? (schist, shale, granite)

All of them

Extrusive igneous rock textures can be:

Aphanitic or glassy or fragmental texture

Which of the following words may be used to describe portions of rock with porphyritic texture?

Aphanitic, Phenocrysts, and Groundmass

Cross beds indicate:

Average flow direction

Which of the following melt compositions do you expect to travel long distances?

Basalt melts

Where would you expect a chemical sedimentary rock like rock salt to be deposited?

Beach

What would you call a rock that has pebble-size angular clasts?

Breccia

Which of the following arrangements represent a correct sequence of deposition away from the source?

Breccia<Conglomerate<Sandstone<Shale

Lithification involves:

Burial, compaction, and cementation

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?

C is younger than B and A, A and B are older than I, and C is younger than I

Which of the following pairs of minerals are part of the continuous reaction series in Bowen's Reaction Series?

Ca-rich plagioclase and Na-rich plagioclase

What is the dominant mineral composition of marble?

Calcite

Which of the following is a dominant mineral in limestone?

Calcite

Two magma chambers of similar size are undergoing crystallization. Chamber A is tabular. Chamber B is spherical. Which chamber cools faster?

Chamber A

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?

Chamber Y

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 neo-crystallization?

Chlorite

Name an organic sedimentary rock

Coal

Which of the following rock can be ignited?

Coal

All phaneritic textures are:

Coarse-grained, derived from magma, and cooled slowly

Give an example of a LIP in continental US

Columbia River Flood Basalts

List 3 tectonic and/or mantle processes that trigger decompression melting

Continental rifting, sea-floor spreading, and mantle plumes

Which of the following rocks is made up entirely of shells or marine organisms?

Coquina

Ripple marks on a sandstone indicate:

Current flow conditions

Mafic igneous rocks tend to have -color shades

Dark

What kind of melting do you expect in a continental rift tectonic setting?

Decompression melting

What kind of melting do you expect just under a mid-ocean ridge?

Decompression melting

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

Give an example of a place currently undergoing continental rifting

East African Rift

Quartzite and marble lack foliation because they have:

Equant mineral grains

Which of the following tectonic processes cools rocks inside the Earth?

Exhumation

Pyroclastic flow occurs in:

Felsic melts flows and extrusive settings

All aphanitic textures are:

Fine-grained, derived from lava, and cooled faster

Principle of uniformitarianism states that:

Geologic processes occurring now happened throughout Earth's history

The characteristic mineral for subduction zone metamorphism which imparts a blue hue to the subduction zone metamorphic rocks is:

Glaucophane

Which of the following rocks contain banded foliation? (gneiss, migmatite, schist, slate)

Gneiss and migmatite

During metamorphic recrystallization, there is a change in:

Grain-size of the protolith minerals, and texture

A coarse-grained magmatic igneous rock with 65% SiO2 and containing minerals like quartz, K-feldspar may be called:

Granite

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

Great Barrier Reef

Porphyritic rocks are named for the size of:

Groundmass grains

Sediments eroded from the Putnam County by the Caney Fork river may be deposited in:

Gulf of Mexico

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

Hawaii

The rock-type produced by contact metamorphism is called:

Hornfels

Intra-plate volcanism is seen at:

Hotspots

Chemical alteration of ocean floor basalts is an example of:

Hydrothermal Metamorphism

Three sedimentary rocks layers A, B, and C are arranged inlayers 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?

I is older than both B and C

A dike intrudes into:

Igneous, sedimentary, and metamorphic rocks

A porphyritic texture is one in which:

Individual crystals are a mix of coarse and fine-grained crystals

A phaneritic texture is one in which:

Individual crystals can be seen with the naked eye

An aphanitic texture is one in which:

Individual crystals cannot be seen with the naked eye

Porphyritic textures indicate:

Initial slow cooling and then fast cooling

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?

Intermediate P/T

Felsic Magma:

Is more viscous than mafic magma

As a mantle rock moves from A to B (upwards), what happens?

It begins to melt via decompression

Flood basalts are characteristic of:

LIPs

The early Cambrian 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?

Labrador, Canada was a shallow marine underwater region close to the Equator

LIP is:

Large Igneous Provinces

Hot rock melt on the Earth's surface is called

Lava

The dominant rock-type in coral reefs is:

Limestone

What is the parent rock for marble?

Limestone

Match the P/T conditions with the corresponding rock environment pair

Low T/High P - Accretionary Prism High T/Low P - volcano tops High P/High T - Deeper parts of subduction zone Dynamic - Mylonites

What kind of igneous rocks do you expect at mid-ocean ridges?

Mafic fine-grained

Composition of the Earth's mantle is:

Mafic to ultramafic

Hot rock melt inside the Earth is called

Magma

How would you get an igneous rock from another igneous rock?

Melting

Which of the following rocks would you expect to react with acid?

Micrite, fossiliferous limestone, and chalk

Which of the following is a mixed rock?

Migmatite

Which of the following rocks have banded foliations?

Migmatite

During metamorphism in a compressive stress field, how does the minerals acquire preferred orientation?

Mineral long axes align normal to the direction of maximum compressive stress

Why does molten rock move upward through the Earth's mantle?

Molten rock is less dense than the surrounding solid rocks

Regional metamorphism is typical of:

Mountain belts

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:

Mudcracks

Which of the following rocks display a stunningly black glassy texture?

Obsidian

Which of the following minerals crystallize via the discontinuous reaction series?

Olivine, pyroxene, and amphibole

Which of the following is a chemical sedimentary rock?

Oolitic LImestone

All intrusive igneous rocks have:

Phaneritic texture

Coarse-grained crystals in porphyritic textures are called

Phenocrysts

Another name for fragmental texture is

Pyroclastic texture

Which of the following is a dominant mineral is sandstone? (calcite, quartz, olivine, or plagioclase feldspar)

Quartz

When a sandstone is metamorphosed, it turns to:

Quartzite

What does a black shale tell about its depositional environment?

Reducing marine conditions?

How would you get a gneiss from phyllite

Reheating

How would you get a metamorphic rock from an igneous rock?

Reheating

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

Rise and fall of sea-level

In most types of metamorphism, bulk element composition of parent rock is:

Same as that of the parent rock

A sandstone sample A has sub-angular sand grains, while a sandstone sample B has rounded sand grains. Which of the following statements are true?

Sample B traveled more distance than sample A

Which of the following metamorphic rocks have visible mineral grains?

Schist

Which is the correct sequence for increasing metamorphic grade inside the Earth?

Slate-Phyllite-Schist-Gneiss

Which of the following minerals is found in impact craters only?

Stishovite

List the 4 tectonic settings where igneous activity occurs:

Subduction zones, midocean ridges, continental rifts, and hotspots

Where would you expect coal to be deposited?

Swamps

A conglomerate sample consists of well-rounded clasts of granite, angular clasts of mica-schist, and individual mineral fragments derived from granite and mica-schist. What can you infer about the source region of the sandstone?

The basin where sandstone was deposited received sediments from both igneous and metamorphic terrains, igneous terrain was closer to the source than the metamorphic terrain, and the combined source region dominant mineralogy is quartz, feldspar, biotite, and muscovite

Shock metamorphism is associated with:

Ultrahigh P/High T

What does red shale tell us about its depositional conditions?

The environment of deposition was exposed to atmosphere

Formation of migmatite is an indication of:

The rock has just entered the zone of melting the Earth

Which of the following statements are true about sedimentary formations?

They are arranged in layers, they are mappable, and they may contain sedimentary structures

Which of the following rocks is not derived from an igneous rock melt?

Tuff

An igneous rock containing <45% SiO2 is called:

Ultramafic Rock

Which of the following melt compositions are arranged in the order of increasing viscosity?

Ultramafic<Mafic<Intermediate<Felsic

Which of the following melt compositions are arranged in the order of increasing volcanic explosivity?

Ultramafic<Mafic<Intermediate<Felsic

A metamorphic rock contains the minerals coesite and diamond. What can you infer about the P/T conditions of the rock?

Very high P

Vesicles in vesicular textures are remnants of:

Volatile passages in an igneous rock

Fragmental texture is formed from:

Volcanic ash and volcanic rock debris

In a flux-induced melting, which of the following can act as flux?

Water vapor, carbon-dioxide, and sulfur dioxide

How would you get a conglomerate from a granite?

Weathering

Arrange in correct order the set of processes leading to a clastic rock formation

Weathering-Erosion-Deposition-Burial-Compaction-Cementation

A magma that is rich in volatiles is called:

Wet magma

Felsic igneous rocks tend to have -color shades

light