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HotE > Lecture 2 - Geology of Ontario + > Flashcards

Lecture 2 - Geology of Ontario + Flashcards

1
Q

what are the four layers of ontario

A

precambrian - Canadian shield (plate collision and mountains) , lower paleozoic (tropical seas), pleistocene (glaciations), present day (built landscape)

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2
Q

how long ago was layer II deposited

A

600-350 Ma

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3
Q

what is layer II made of

A

shield covered by younger sedimentary rocks in southern ontario

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4
Q

what is layer I known as

A

the Canadian shield

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5
Q

where are paleozoic sedimentary rocks exposed

A

along the niagara escaprtment

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6
Q

how long ago was layer I deposited

A

3-2.6 Ba

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7
Q

formation of the Niagara Escarpment formed

A

rocks are 400-500 Ma, but the actual escarpment as a landform is young. it was formed by glacial and fluvial erosion, which includes Niagara Falls today

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8
Q

how fast has niagra falls eroded in how long

A

10 km in over 12,500 years, which is quite rapid in geological time

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9
Q

cap rock

A

resistant rocks on top of more easily eroded rocks where water flows. cap rock is lockport dolostone, and the easily eroded rocks are rochester shale at NF

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10
Q

how do falls/escarptments retreat

A

undercutting below cap rocks leads to erosion of the softer rocks, and eventually the breaking off of the cap rock

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11
Q

what are the exposed layers of the hamilton escarpment

A

ancaster, gasport, rochester, irondequois, reynales, thorold, grimsby

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12
Q

who developed the first clean labs to measure Pb isotopes

A

Clair Petterson

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13
Q

how old is the canyon diablo metetoerite

A

4.55+/-70 Ma

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14
Q

what established the age of the solar system

A

canyon diablo meteorite dating

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15
Q

absolute geologic age

A

understanding when events actually happened “how old is it?”

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16
Q

what rock is best for geologic aging

A

igneous

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17
Q

relative geologic age

A

understanding when events occurred relative to one another. “Which came first?”

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18
Q

stratigraphy

A

the part of geology that deals with the formation, character, sequence, distribution, and correlation of sedimentary rocks and the fossils contained in them

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19
Q

stratum/strata

A

single beds/layers of beds

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20
Q

stratigraphic succession

A

the vertical sequence of layering strata

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21
Q

what did nicolas steno do (1636-1686)

A

realized shark teeth were entombed in sedimentary rocks rather then grown within them. and that crystalss formed in liquid state originally in igneous rocks. invented the basic laws of stratigraphy

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22
Q

principle of original horizontality

A

beds of sediment laid down in water form horizontal or near-horizontal layers. layers now eroded were once continuous.

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23
Q

principle of superposition

A

sedimentary layers are deposited in time sequence, with the oldest on the bottom and the youngest on the top

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24
Q

principle of lateral continuity

A

strata extend continuously in all directions until they are terminated by thinning at the edge of a basin, end abruptly at a barrier to sedimentation, or grade laterally into a different sediment type

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25
Q

what is an example of eroded original horizontality

A

the tapeats sandstone layer in the grand canyon has been eroded by the colorado river

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26
Q

uniformitarianism

A

the theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes. “the present is the key to the past”

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27
Q

principle of cross-cutting relationship

A

states that a rock unit, sedimentary body, or fault that cuts another geologic unit is younger than the unit that was cut

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28
Q

principle of included fragments

A

fragments of rock within a larger rock unit are older than the rock in which they are enclosed

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29
Q

three types of unconformities

A

disconformity, angular unconformity, and nonconformity

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30
Q

disconformity

A

layers above and below the unconformity are parallel to one another

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31
Q

what is the great unconformity

A

the Canadian shield is 2.5 billion years old and the next layer ontop is only 5 million years.

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32
Q

angular unconformity

A

younger beds overlie tilted or folded beds

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33
Q

nonconformity

A

younger beds overlie older metamorphic or plutonic rocks

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34
Q

stratigraphic correlation

A

matching of strata from one region to another. using the study of lithostratigraphy

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35
Q

lithostratigraphy

A

study of rock types (lithology)

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36
Q

formations

A

distinctive rock units that can be mapped over a large area. they are usually names after a type locality where the rocks were first described.

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37
Q

sub-divisions of formations

A

they are sub-divided into members.

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38
Q

lumping of formations

A

formations are lumped together to form groups

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39
Q

how are stratigraphic layers zoned and arranged

A

according to relative time of deposition using the range of fossils

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40
Q

geologic range of fossils

A

time interval between dirst and last appearance of each species

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41
Q

zone (biozone)

A

a stratigraphic interval defined by its fossil content, and usually given the name of a characteristic fossil present in that interval

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42
Q

chemostratigraphy

A

using ratios of chemical isotpes. excursions in chemical signatures (ex. isotopic ratios) can record global environmental changes

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43
Q

magnetostritigraphy

A

stratigraphic correlation on the basis of magnetic properties

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44
Q

study of earths magnetostritigraphy

A

changes in magnetic polarity directions recorded in rocks and sediments. polarity of the earth’s magnetic field is recorded at the time of deposition. the fine-grained magnetic minerals (magnetite) orient themselves when settling from suspension with the earth’s magnetic field. it is applicable only in certain environments, such as the deep sea.

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45
Q

what are the four geologic eras often used

A

cenozoic, mesozoic, paleozoic, precambrian

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46
Q

which geologic era was the Niagara Escarpment made in

A

paleozoic

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47
Q

what period were the dinosaurs from

A

jurrasic

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48
Q

largest geochronologic time unit

A

eon

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49
Q

what are the four eons

A

phanerozoic, proterozoic, archean, hadean

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50
Q

what is the precambrian

A

proterozoic, archean, and hadean. it is an informal unit of time

51
Q

what time range is the phanerozoic eon

A

531 Ma to now

52
Q

what time range was the proterozoic eon

A

2.5Ga to 541 Ma

53
Q

what time range was the archean eon

A

4Ga to 2.5 Ga

54
Q

what time range was the hadean eon

A

4.54 Ga to 4.0 Ga

55
Q

what are the four geologic time units

A

eon, era, period, epoch

56
Q

what eon, era, period, epoch are we in

A

phanerozoic, cenozoic, quaternaty, holocene

57
Q

what is hadean named after and why

A

greek god hates because it literally looked like hell

58
Q

what percent of earths history is phanerozoic

A

12%

59
Q

what was the time range of the paleozoic era

A

541Ma to 252 Ma

60
Q

what was the time range of the mesozoic era

A

252Ma to 66 Ma

61
Q

what is the time range of the cenozoic era

A

66 Mz to today

62
Q

what is the time range of the holocene epoch

A

11.8 Ka to today

63
Q

what is the second largest geochronic time unit

A

eras

64
Q

how many eras are they and how are they divided

A

10 eras, with three in the phanerozoic eon

65
Q

what are the three phanerozoic eras

A

paleozoic era, mesozoic era, and cenozoic era

66
Q

what is the third largest geochronic time unit

A

periods

67
Q

how many periods are there, and how may in the cenozoic

A

22 total with three in the cenozoic

68
Q

what three periods are in the cenozoic era

A

paleogene, neogene, and quaternary

69
Q

what is the time range of the paleogene period

A

66Ma to 23 Ma

70
Q

what is the time range of the neogene period

A

23Ma to 2.6Ma

71
Q

what is the time range of the quaternary period

A

2.6 Ma to present

72
Q

How did earth get to how it is today

A

started as molten, there was differentiation of materials according to density, formation of the earths layers, huge impact creates the earths moon, and then the atmosphere started to originate

73
Q

how long ago did the earth form from the condensation of the condensation of material from the solar nebula

A

4.5 Ba

74
Q

Conditions in the hadeon eon

A

likely that almost the entire earth was molten magma - magma ocean. it began to cool over a few 100 million years, forming igneous rocks in the process. it was very hot from the residual heat from planetary accretion and the atmosphere has no oxygen

75
Q

what has been happening to the temperature of the earth since the hadeon era

A

it has been slowly cooling down internally

76
Q

what is komatitte

A

a type of basalt (ultramafic - rich in iron and magnesium). it is quite dense, and formed the earliest ocean crust at temperatures above 1100 Celcius. The spreading centres were probs produced by convection currents in the mantle

77
Q

how were convection currents driven in the hadeon eon

A

it is not fully understood, but by the heat of the core. some of the earliest crust may have sunk to form the outer core

78
Q

ocean crust density

A

3 g/cm^3

79
Q

continental crust density

A

2.7 g/cm^3

80
Q

what is bowen’s reaction series

A

an idealized progression of minerals produced by cooling basaltic magma. the low end of the scale is 700 deg, and all minerals crystallize into solid rock. The high end of the scale is 1250 deg, and all the minerals exist in a molten state

81
Q

where are mafic rocks found on the bowens reaction series

A

on the high end in high temperatures

82
Q

where are felsic rocks found on the bowens reaction series

A

on the low end in low temperatures

83
Q

how does the bowens reaction series affect magmas?

A

lavas erupted early from a magma body may be basalt (mafic), as they cooled in high temperatures. they would be rich in iron, magnesium, and calcium.
lavas erupted late from a magma body may be andensites (felsic). they would be low in sodium, potassium, and silica

84
Q

which temperature of rock cooling results in richness of magnesium, calcium, and iron

A

high temperature

85
Q

formation of early oceans time

A

some time before 4Ga

86
Q

formation of early oceans process

A

ocean crust formed underwater, adding lots of water to lavas. the melting of wet crust at subduction zones formed andesitic magmas.

87
Q

where did water on earth first come from

A

outgassing from magmas. likely came as components in many many comets. comet water has similar isotopic composition to ocean water.

88
Q

how did continental crust develop

A

the continued subduction of sediments and water with basaltic oceanic crust creates more felsic magmas over time, which creates continental crust. This lead to patches of continental crust.

89
Q

how long ago did continental crust develop

A

4.4 Ga in the zircon age

90
Q

what is the earliest evidence of water

A

4.4 Ga zircon has stable oxygen isotope rations indicating that zircon reacted with water. evidence that deep oceans had formed by 3.8 Ga

91
Q

what was water from meteorites like

A

meteorites were canbonaceous chondrites (felsic), containing up to 20% H2O. it was locked up in clay minerals. Just like how most of earths water is currently locked up in the crust

92
Q

early atmosphere composition

A

not exactly known
- abundant hydrogen
- no free oxygen
- anoxic or reducing
- high CO2 levels

93
Q

modern atmosphere composition

A
  • nitrogen
  • oxygen (21%)
  • argon
  • carbon dioxide (0.03%)
  • water vapor
  • other gasses
94
Q

when did oxygen start to build up in the atmosphere

A

early archean (3.8 - 3.4 Ga)

95
Q

what two processes built up oxygen

A

photochemical dissociation and photosynthesis (more in terms of volume)

96
Q

photochemical dissociation

A

water molecules split by UV radiation in upper atmosphere (2H2O + UV -> 2H2 + O2)

97
Q

photosynthesis in early photosynthetic organisms

A

cyanobacteria and other algae take up CO2 for energy and release oxygen

98
Q

cyanobacteria and how old they are

A

earliest forms of life. recognized in 3.5 Ga old Archean rocks. algal mats build to form stromatolites

99
Q

banded iron formations (BIFs) formation

A

Because Fe was more prevalent in ocean during archean period as it was released from abundant hydrothermal vents at mid-ocean ridges. cyanobacteria produced some oxygen. the oxygen and dissolved iron combine to form insoluble iron oxide which precipitated out forming thin layer of ocean floor. the alternating times of oxygenated (red) and non oxygenv(black/grey) events.

100
Q

what year rocks are BIFs in

A

common in rocks 3.0-1.8 Ga old, and absent in younger rocks.

101
Q

what did early weathering of rocks do

A

reduced CO2 in the atmosphere, drawing it down. the weathering of igneous rocks (Ca-silicates) produces calcium carbonate and silica. water and co2 react to make carbonic acid/rainwater that reacts with rocks to create new stuff

102
Q

what are the oldest fossils and first evidence of life

A

cyanobacteria (blue-green algae) that is 3.5 billion years old

103
Q

what are the suggester older fossils

A

microfossils (tubes) in BIF deposits in Quebec. They are possibly 3.8 -4.28 Ga

104
Q

what elements are able to produce life

A

carbon, oxygen, hydrogen, nitrogen, phosphorous, and sulphur, all of which are abundant in the solar system

105
Q

what did the Miller-Urey experiment do

A

simulated conditions on early Earth and produced organic compounds (amino acids) from inorganic materials as an analogue of early Earth

106
Q

micelle

A

a ball of chain molecules, single lined

107
Q

what is the importance of extremophiles to getting life where it is

A

extremophiles give a lot of pathways with how we could get to where we are now because of the extreme living conditions they can take

108
Q

what would be the evolution of how cells cam to be

A

chain molecule consisting of a hydrophillis phosphate attached to a fatty acid chain were attracted to other fats, and combines to form balls or sheets. Sheets then form a single layer ball, or a bilayer ball with a vesicle in the middle, which is similar to a cell wall.

109
Q

bilayer ball (liposome)

A

bilayer sheet in the form of a ball, has a vesicle in the middle

110
Q

what played a role in the origin of life

A

concentration of reagents makes polymers
clay or pyrite substrates can also aid in polymerizing organic molecules
rewetting can cause bilayers to form liposomes
wetting and drying concentrates, reagents, and protocells that can replicate may become self-selected for improvement

111
Q

lithotropes

A

live in environments like rocks where they can oxidize inorganic compounds. live off of geochemical energy and consume hydrogen

112
Q

where might have early bacteria lived

A

in and on rocks. they were found in granites in sweden over 3600 m below the surface

113
Q

where on earth did early life forms flourish

A

probably in oceans because salts, solvents, mixing of element create organic compounds. life probably developed at hydrothermal vents at mid-ocean ridges

114
Q

life at hydrothermal vents

A

temps greater than 100 deg, no light, energy from chemosynthesis, microbes (hyperthermophiles), and no fossils from early spreading centres (no preservation?)

115
Q

what did prokaryotes form

A

stromatolies, the oldest known fossils. They are organic structures formed by trapping sediment on sticky bacterial mats. they are columnar structures.

116
Q

cratons and shields

A

oldest parts of modern continents. they are the stable parts of the continental crust that have survived subduction

117
Q

how old is the north american craton

A

over 600 Ma

118
Q

exposed parts of the cratons

A

shields

119
Q

platform or cover rocks

A

the younger rocks covering shields

120
Q

what is the canadian sheild

A

ancient erosional surface. its the inside of a mountain

121
Q

peneplaine

A

ancient erosoinal surface

122
Q

what is the complex geology of cratons

A

they are made of different geological provinces with areas of distinct geology. each represents an ancient micro-continent (terrane) brought together by plate tectonics. they are then welded onto the craton along suture zones.

123
Q

where are the old and young rocks on cratons

A

oldest rocks are in the centre and younger are along the margins

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