Geology 1040 Exam 2
(Know This) Sedimentary rocks are usually layered or stratified
(Know This)
Foliation is the alignment of _________ in a metamorphic rock.
(Minerals) (not correct)
Clay minerals within a slate are changed into mica minerals due to the application of heat to a rock. This is an example of ___________.
(Pressure solution) (not correct)
Geologists classify metamorphic rocks according to ___________.
(The size of their crystals) (not correct)
What are the 4 sedimentary rock formations/ classes?
1. Cement looses clasts (Clastic) 2. Cement loose shells and fragments (Biochemical) 3. Accumulation of organic (Organic) 4. Precipitation of minerals in water (Chemical)
Clastic sedimentary rocks are created by :
1. Course clastics - gravel sized clasts - Breccia - Conglomerate - Arkose - Sandstone
Locations where sediments accumulate. They differ in;
1. Energy regime 2. Sediment delivery, transport and depositional conditions 3. Chemical physical, and biological characteristics
What are the 4 major types of magma and their significance?
1. Felsic 2. Intermediate 3. Mafic 4. Ultra-mafic Felsic has the most Silica and ultra-mafic has the least
Magmas vary chemically due to:
1. Initial source composition 2. Assimilation 3. Partially melting 4. Magma mixing
Melting is caused by :
1. Pressure release 2. Volatile addition 3. Heat transfer
What is the metamorphic process?
1. Recrystallization,- minerals change size and shape. Mineral identity does not change 2. Phase Change,- new minerals form with; - the same chemical formula = polymorph - Different crystal structure 3. Neocrystallization,- the creation of new crystals from old crystals, new mineral structure 4. Pressure Solution,- Mineral grains partially dissolve
Igneous activity takes place in 4 plate tectonic settings
1. Volcanic arcs, bordering deep ocean trenches 2. Isolated hot spots 3. Continental rifts 4. Mid-ocean ridges (mostly here)
To show topography in a rugged, mountainous are, the most appropriate counter interval would be
100 feet
A series of concentric contour lines may indicate
A hill and depression
The degree of edge or corner smoothness
Angularity
Alters magma composition
Assimilation
Where do sedimentary rocks form?
At or near Earth's crust
Plutons may amass into a ____________
Batholith
Because the velocity of sediment setting (deposition) is positively related to grain size for waterborne sediments, fluvial deposits are more likely than glacial deposits to ___________
Be well sorted
Geologists call individual layers of sedimentary rocks __________, whereas several of them together are called __________.
Beds; Strata
Sedimentary rocks are arranged in planar, close to horizontal ____________. Several beds together constitute ______________
Beds; Strata
Marble and quartzite are nonfoliated rocks because ___________.
Both are dominated by minerals that produce equant grains
Contour lines on a topographic map
Cannot be drawn below sea level
Meta = ____________ Morphe = ____________
Change Form
Have minerals precipitating from a water solution. Have a interlocking crystalline structure
Chemical sedimentary rocks
__________________ - The diameter of fragments or grains
Clast Size
__________________ - The mineral make-up of sediments
Clast composition
Lithified detritus (breakdown products of preexisting rocks) forms which kind of sedimentary rock?
Clastic
Classification is based on ________ and _________
Composition; Texture
Intrusion of granite into layers of sedimentary rock would cause
Contact metamorphism
The presence of vesicles in an igneous rock is evidence that the source melt ______________
Contained dissolved volatiles
Plagioclase changed from Ca rich to Na rich
Continuous
Slow cooling, crystals have time to grow, intrusive
Course grained
Created by ripple and dune migration
Cross Beds
Interlocking crystals fit like a jigsaw puzzle
Crystalline
If the volatile content of magma is increased, its viscosity will __________
Decrease
Small tick marks (hachure) on contour lines indicate
Depressions
Cuts across rock layers
Dike (dominate in the extrusive setting)
Minerals start and stop crystallizing
Discontinuous
Similar triples except much larger
Dunes
Roughly equal in all dimensions
Equant
The datum on which all latitudes are based is the
Equator
The removal of detritus from weathered rock at an outcrop is termed _________
Erosion
What are the 5 ways sedimentary rocks are created?
Erosion Weathering Transportation Lithification Deposition
What are evaporites?
Evaporated rock from the Sea or Lake
Igneous rocks that cool quickly at the Earth's surface, chills to fast to grow crystals
Extrusive
Lower viscosity
Faster movement
Si rich minerals melt first which is why ______ melts first
Felsic
Which type of magma has the greatest silica content?
Felsic
Removing a partial melt from its source creates..........
Felsic magma and magic residue
Rapid cooling, crystals don't have time to grow, extrusive
Fine grained
___________ melting occurs at subduction zones because the down-going plates ____________
Flux; Contains abundant water
What are the 2 major metamorphic rock subdivisions?
Foliated and Non-foliated
Metamorphism often creates __________
Foliation
Parallel surfaces or layers in metamorphic rocks
Foliation
Distinct rock packages can also be called
Formations
Pieces of pre-existing rock, often shattered
Fragmental
Made of solid glass or glass shards
Glassy
Result from rapid cooling of lava, Fracture os conchoidal
Glassy textures
Distinct compositional bands, often contorted
Gneiss
What are some examples of Hot Spots
Hawaii, Iceland, and Yellowstone
What are the agents of metamorphism?
Heat, Pressure, Hot fluids, Compression of shear
Fine grained Variety of metamorphic minerals
Hornfels
Metasomatism occurs when
Hydrothermal fluids add ions to the rock and/or remove other ions
Formed by cooling from a melt
Igneous rocks
Dimensions are not equal
Inequant
Igneous rocks that cool out of sight, underground. Cooling rate is slower. Grows large crystals
Intrusive
Why does magma rise?
It is less dense than the rock around it and the weight of overlapping rock creates pressure
Within a single mountain range, ____________.
It is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, intermediate0 and low-grade rocks
What does adding volatile do?
It lowers the melting point temperature
________ is on the surface and _________ is below the surface
Lava; Magma
The formation of magma within Earth is NOT caused by which of the following processes
Loss of volatiles to the atmosphere
Hot = __________ and Cool = ___________
Low viscosity; High viscosity
Result is a blob of 1 rock suspended in the other
Magma mixing
The formation of a hotspot is thought to be associated with ____________
Mantle Plumes
Coarsely crystalline calcite or dolomite
Marble
Porphyroblasts are _______________
Metamorphic minerals that have grown larger than the rest of the minerals
____________ can alter any protolith
Metamorphism
Metamorphism changes __________
Mineralogy
No planar fabric evident?
Non-foliated
Thermal (contact) metamorphism produces ________.
Non-foliated rocks only
Contour lines on a map connect points ___________
Of equal elevation
The mantle is made up of ____________ which is ultra-mafic
Peridotite
Fine grained Mica rich rock
Phyllite
An irregular-shaped and blob-like igneous rock body that cooled beneath the surface of Earth is a _____________
Pluton
A mixture of course and fine grained minerals
Porphyritic
An igneous rock with a mixed texture of course crystals (phenocrysts) surrounded by fine crystals (groundmass) is termed _____________
Porphyritic
The primary difference between breccia and conglomerate is that conglomerate ......
Possesses more angular grains than breccia
Cementation of sediments occurs when minerals _____________ the space between sediment grains.
Precipitate in
The application of _______ during metamorphism causes elongated crystals to align parallel with each other. When this happens, the rock develops _______.
Pressure; Foliation
The datum on which all longitude is based is the
Prime Meridian
Preexisting rock that is subsequently altered to form a metamorphic rock is termed a _________.
Protolith
Fragments of violent eruptions
Pyroclastic
Ash, and larger fragments of pumice are all examples of ?
Pyroclastic Debris
Almost put quartz in composition Quartz and sandstone
Quartzite
Collision of two continental plates would cause
Regional metamorphism
Exposure due to sea level fall
Regression
Dynamothermal (regional) metamorphism occurs when ___________.
Rock becomes deeply buried during continental collision and mountain building
Fine to course grain Large micas
Schist
The zero contour line is also known as ___________
Sea level
If mineral grains have been smeared out, the rock was subjected to __________.
Shear
Inject parallel to rock layering
Sill
What makes up an igneous rock?
Size, Shape, and Arrangement
Biochemical limestones are dominantly carbonate mud and fragments of ____________.
Skeletons of marine invertebrates made of calcite and aragonite
Fine grained Low grade metamorphic shale
Slate
The mantle is composed entirely of ___________
Solid peridotite
____________ - The uniformity of grain size
Sorting
The degree to which a class nears a sphere
Sphericity
As compared to metamorphism, diagenesis _______________.
Take place at lower temperatures and pressure
Metamorphic index minerals help geologists determine
Temperature and pressure conditions during metamorphism
Metamorphic changes are due to variations in
Temperature, Pressure, and Reactions with water
Metamorphism changes __________
Texture
Sedimentary rocks are classified on the basis of ____________ and ____________
Texture ; Composition
Protoliths undergo slow solid-state changes in ____________ and _____________
Texture; Mineralogy
The absence of preferred orientation of mineral grains in a metamorphic rock may be due to
The absence of platy minerals like mica, The lack of differential stress (directed pressure) during metamorphism, The absence of elongate minerals like amphibole
The assemblage of minerals in a metamorphic rock helps geologists determine
The chemical composition of the parent rock, The temperature at which metamorphism took place, The pressure at which metamorphism took place
Information on the borders of a topographic map does not include what?
The cost of the map
The term "Metamorphic Grade" refers to
The degree to which it has changed from its original state
The Finer the grain size, _________________
The less energy it took
Foliation and lineation are terms describing
The orientation of minerals in metamorphic rocks
What is an agent that does not cause metamorphism?
Time
Flooding due to sea level rise
Transgression
Grains become rounded primarily during __________
Transportation
This is precipitated from ground water
Travertine
Which of the following does not reflect transport distance?
Type of cement
LIP, or large igneous province's are ..............
Unusually large outpourings of magma
Air pockets
Vesicles
Speed of magma flow governed by ________
Viscosity
A vent where molten rock comes out of Earth
Volcano