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Understanding the Earth > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What are the characteristics that fulfill the definition of a mineral?

A

Naturally occurring
Inorganic
Solid
Forms a crystalline structure
Chemically homogeneous

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2
Q

What are the definitions of the common physical properties used for identifying minerals?

A

extrusive - cooled above the surface (volcanic)
intrusive - cooled below the surface (plutonic)

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3
Q

What are the relative abundance of major elements in Earth’s crust?

A

Silicon and oxygen

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4
Q

What is meant by the rock cycle?

A

The rock cycle is the how material in the earth goes through the process of forming into different types of rocks
The life cycle of rock and minerals

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5
Q

What is magma?

A

molten rock below the surface

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6
Q

What is lava?

A

molten rock above the surface

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7
Q

What is the source for magma?

A

water within oceanic crust is brought into the mantle in a subduction zone. water is released into the surrounding hot mantle rock at a depth of about 100km and promotes melting

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8
Q

What are the mechanisms that trigger rock to melt at depth?

A

a decrease in pressure will allow rocks to melt
magma with more water will remain a liquid at a lower temp
heat transfer

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9
Q

What are the different magma types?

A

Mafic
Intermediate
Felsic

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10
Q

How do the different magma types compare in composition?

A

Mafic - dark colored minerals
Intermediate - mix of light and dark minerals
Felsic - light colored minerals

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11
Q

What are the different processes that can affect a magma’s final composition?

A

Assimilation - new minerals are added to the magma from surrounding country rock
Magma Mixing - magma chambers combine together
Partial Melting - induce melting of solid rock
- minerals with higher silica content melt first
Fractional Crystallization - crystals form from magma cooling and settle to floor of chamber

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12
Q

Know major points of Bowen’s Reaction Series

A

dark colored minerals are the first minerals to crystallize
light colored minerals are the last minerals to crystallize

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13
Q

How are igneous rocks classified?

A

Magma types: Mafic, Intermediate, Felsic
Texture: extrusive and intrusive

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14
Q

What are the forms chemical weathering?

A

Dissolution
- minerals dissolve in water
- salts and carbonates are susceptible
- H2O acidity can be important
Hydrolysis
- the replacement of cations in mineral structures using H+ ions
- affects silicates
Oxidation
- minerals react with oxygen to form an oxide

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15
Q

What are the forms of physical weathering?

A

Decrease in pressure - results in expansion
Frost - expansion with water and ice
Roots - can work into the fractures and make them bigger
Salt - mechanical weathering of granite from salt on coastline

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16
Q

What are the major clastic sedimentary rocks?

A

Shale
Siltstone
Sandstone
Conglomerate

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17
Q

How are clastic sedimentary rocks classified?

A

grain size
sorting
roundness

18
Q

What are the major chemical sedimentary rocks?

A

Evaporites - halite, gypsum
Chemical Limestone (travertine)
Biochemical Limestone
Chert - microcrystalline silica
Coal

19
Q

How do chemical sedimentary rocks form?

A

Evaporites - precipitate when water evaporates
Chemical Limestone - precipitation of calcium carbonate from ground and surface water
Biochemical Limestone - calcium carbonate becomes incorporated into marine organism shells and skeletons
Chert -
Coal - a sedimentary rock derived from plant remains

20
Q

What are the sedimentary environments where particular sedimentary rocks are found?

A

Alluvial Fans - poorly sorted
Fluvial (river) Environment
Desert
Delta
Clastic coastlines
Lakes
Glacial Environments
Shallow marine environment

21
Q

What causes rocks to metamorphose?

A

heat and/or pressure of an existing rock(protolith)

22
Q

What are the different things that can happen to a rock when it undergoes metamorphism?

A

Neocrystallization - growth of new minerals that are different from the starting rock; atoms migrate or diffuse through solid crystals and/or dissolve and re-precipitate at grain boundaries
Recrystallization - change the shape and size of grains, but not the mineral identity
Phase changes - mineral changes into another mineral with same composition but different crystal structure
Pressure solution - minerals prefentially dissolve at grain boundaries where stress occurs
Mineral migration/remobilization
Physical changes - deformation, rotation, shearing

23
Q

How are metamorphic rocks classified?

A

Foliated
Non-foliated

24
Q

What is foliation?

A

directed pressure/differential stress
directional/parrallel alignment or banding

25
Q

What is metamorphic grade?

A

is the difference in the amount of heat and pressure occur on a rock

26
Q

What are the different types of metamorphism?

A

Contact - application of just heat
Regional - application of heat and pressure

27
Q

Qualities of the core

A

Outer core
- liquid Fe and Ni
- density 10-12 g/cm^3
Inner core
- solid Fe and Ni
- density 13 g/cm^3

28
Q

Qualities of the mantle

A
  • peridotite composition (~40% SiO2)
  • ~2800 km thick
  • density 3.3-6 g/cm^3
  • ~80% of Earth’s mass and volume
29
Q

Qualities of the crust

A

made up of the continental and oceanic crust
oceanic crust is thinner and more dense than continental crust

30
Q

Qualities of the lithosphere

A

solid (rigid)
crust + upper mantle

31
Q

Qualities of the asthenosphere

A

solid (but deformable)
1-2% molten

32
Q

Qualities of the continental crust

A
  • granitic composition (60-70% SiO2)
  • density ~2.7 g/cm^3
  • 20-70 km thick
33
Q

Qualities of the oceanic crust

A
  • basaltic composition (~50% SiO2)
  • density ~2.9 g/cm^3
  • 4-7km thick
34
Q

What are the concepts of the continental drift hypothesis?

A

Continental fit
Glacial Deposits and evidence of ice sheets on multiple continents
Matching geology (only certain geology can be found in certain areas where the continents are not now)
Matching fossils
Magnetic declination and inclination (with the direction of rocks going towards the magnetic pole and changing)

35
Q

What are the concepts involved in seafloor spreading

A

is the mechanism to move the continents
was discovered through the mid-oceanic ridge
2 oceanic plates moving apart and the space being filled with magma and cooled which forms a ridge
Also the age of the ocean crust

36
Q

What are the characteristics of convergent plate boundaries?

A

Ocean crust subducts beneath continental crust and melts
Forms volcanic chains and produces earthquakes
Continental crust will not subduct
When 2 continental crusts collide, they for a mountain chain

37
Q

What are the characteristics of divergent plate boundaries?

A

Also called spreading boundary, mid-ocean ridge, or ridge
Plates move apart from one another
New ocean crust forms
Forms a mid-oceanic ridge
Results in the formation of ocean basins

38
Q

What are the characteristics of transform plate boundaries?

A

Also, called Transform fault
Plates slide past one another
No ocean crust is consumed or generated
Produce just earthquakes

39
Q

What are the characteristics of hot spots?

A

a stationary mantle plume that has burned a hole in the crust and produces volcanism as the plate drifts over it
Ex) Yellowstone

40
Q

What are the characteristics of continental rift systems?

A

a divergent boundary initiated on a continent
if they are successful, they eventually produce an ocean basin

41
Q

How has paleomagnetism and polar wander curves contributed to the theory of plate tectonics?

A

When igneous rock cool, they align with the Earth’s magnetic field. Scientist saw how the diploes of rocks where facing and used magnetic declination and inclination to see how the magnetic pole has changed and showing how the plates would have moved.

Understanding the Earth (2 decks)

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