Geology Test 2
Which of the following rocks contain banded foliations?
Gneiss Migmatite
Which of the following is a biochemical sedimentary rock?
Chalk
Give an example of a place currently undergoing continental rifting.
East African Rift
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
What does sorting of a clastic sedimentary rock indicate?
Number of sources involved
Which of the following is a chemical sedimentary rock?
Oolitic limestone
What is the primary factor that keeps the mantle rocks from melting at very high temperatures of ~3000°C?
Overburden pressure
Metamorphic grade implies
P, T conditions of a rock environment
Metamorphism implies:
P, T, Stress, Fluids condition of a rock environment
A vesicular texture is one in which:
Pores are abundant
Burial metamorphism is common in:
Sedimentary basins
The grand canyon carved out by the Colorado river exposed:
Sedimentary rocks Igneous rocks 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 is the correct sequence for increasing metamorphic grade inside the Earth?
Slate- phyllite- schist- gneiss
Which of the following is a possible metamorphic temperature?
450 °C
Alluvial fan is a type of depositional environment where the following happens:
A change in river flow velocity A change in slope of the land Deposition of sediments eroded form mountain tops
Which of the following situations are impossible in nature?
A granite rock from olivine A metamorphic rock with marine shell fragments
Which of the following words may be used to describe portions of rock with porphyritic texture?
Aphanitic Phenocrysts Groundmass
Extrusive igneous rock textures can be:
Aphanitic or glassy of fragmental texture
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 (i.e. closest to farthest)?
Breccia- Conglomerate-Sandstone-Shale
Lithification involves:
Burial Compaction Cementation
Three sedimentary rock layers A, B, 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 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
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. 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 rocks can be ignited?
Coal
All phaneritic textures are:
Coarse-grained Derived from magma Cooled slowly
Give an example of LIP in continental US.
Columbia River Flood Basalts
Which of the following processes can turn a sedimentary rock into a metamorphic rock?
Contact metamorphism Subduction metamorphism Burial metamorphism
List 3 tectonic and/or mantle processes that trigger decompression melting
Continental rifting Sea floor spreading Mantle plume
Which of the following rocks is made up entirely of shells of marine organisms?
Coquina
Ripple marks on a sandstone indicate:
Current flow conditions
Mafic igneous rocks tend to have ____ color shaded
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
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 Mafic melt flows
All aphanitic textures are:
Fine-grained Derived from lava Cooled faster
Principle of uniformitarianism states that:
Geologic processes occurring now happened throughout the Earth's history
The characteristic mineral for subduction zone metamorphism which impacts a blue hue to the subduction zone metamorphic rocks is:
Glaucophane
During metamorphic recrystallization, there is a change in:
Grain-size of the protolith minerals 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 the NE Australia known as?
Great Barrier Reef
Porphyritic rocks are named for the size of:
Groundmass grains
Sediments eroded from the Putman County by the Caney Fork river may be deposited in:
Gulf of Mexico
Give an example of a location experiencing hotspot-induced volcanism?
Hawaii
1.) 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, 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?
I is older than both B and C
A dike intrudes into:
Igneous rock Sedimentary rock Metamorphic rock
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
Flood basalts are characteristic of:
LIPs
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?
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
Felsic igneous rocks tend to have ____ color shades
Light
The dominant rock-type in coral reefs is:
Limestone
What is the parent rock for marble?
Limestone
Hot rock melt inside the Earth is called_____
Magma
Match the P/T conditions with the corresponding rock environment pair.
Low T/High P metamorphism - Accretionary Prism High T/ Low P metamorphism - Volcano tops High P/ High T metamorphism - Deeper parts of subduction zones Dynamic metamorphism - 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
Which of the following is a dominant mineral in limestone?
Marble
How would you get an igneous rock form another igneous rock?
Melting
Which of the following rocks would you expect to react with acid?
Micrite Fossiliferous limestone Chalk
Which of the following is a mixed rock?
Migmatite
Which of the following rocks have banded foliations?
Migmatite
During metamorphism is 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
In Q29., would you expect olivine as a mineral fragment in the sandstone?
No
Regional metamorphism is typical of:
Mountain belts
A small stream in an arid region which is experiencing sever 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 Amphibole
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 in sandstone?
Quartz
When a sandstone is metamorphosed, it turns to:
Quartzite
Which of the following metamorphic rocks are coarse-grained?
Quartzite Gneiss Schist
What does a black shale tell about its depositional environment?
Reducing marine conditions
How would you gat a gneiss from phyllite?
Reheating
How would you get a metamorphic rock from and 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 subangular sand grains, while a sandstone sample B has rounded sand grains. Which of the following statement are true?
Sample B traveled more distance than sample A
Which of the following metamorphic rocks have visible mineral grains?
Schist
Which of the following rocks may be a protolith of gneiss?
Schist Schale Granite
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 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 then the metamorphic terrain. The combined source region dominant mineralogy (i.e., considering both the terrians together) is quartz, feldspar, biotite, muscovite
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 had 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 They may contain sedimentary structures
Which of the following rocks is not derived form an igneous rock melt?
Tuff
Shock metamorphism is associated with:
Ultrahigh P/ High T
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 lava Volcanic rock debris
In a flux-induced melting, which of the following can act as flux?
Water vapor carbon dioxide sulfur dioxide
How would you get a conglomerate from 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