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HotE > Lecture 4 & 5 > Flashcards

Lecture 4 & 5 Flashcards

1
Q

when did simple life start

A

3.5 Ba

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2
Q

When did complex life start

A

600-500 Ma

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3
Q

what eon was simple life

A

proterozoic eon

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4
Q

what eon is complex life

A

phanerozoic eon

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5
Q

lavas erupted early from a magma body

A

rich in iron, magnesium, and calcium - basalts (mafic)

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6
Q

lavas erupted later from a magma body

A

rich in sodium, potassium, and silica - andesites (felsic)

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7
Q

photosynthesis in early organisms

A

cyanobacteria and other algae take up CO2 for energy and release oxygen. This was volumetrically significant.

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8
Q

why was complex life maybe not around sooner

A

there wasn’t enough oxygen, and it was just starting to be build up by cyanobacteria and other algae

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9
Q

Miller-Urey experiment

A

showed that life was possible from the early conditions on earth through a simulation that produced the essential amino acids

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10
Q

what is an alternate option than soup origin

A

the needed organic molecules are also present in comets and meteorites that might have brought them to earth

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11
Q

hydrothermal vents life

A

hyperthermophile microbes lived at temps greater than 100 degrees, with no light and got energy from chemosynthesis. There are no fossils of this from early spreading centres

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12
Q

cratons and shields

A

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

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13
Q

North American Craton

A

Archean (4 - 2.5 Ga) and Proterozoic (2.5 Ba to 538 Ma) rocks. the formation is older than 600 Ma. younger rocks surround the shield, and the shield itself it the remains of an old mountain.

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14
Q

shields

A

exposed parts of cratons with no cover rock

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15
Q

platform or cover rocks

A

younger rocks covering cratons

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16
Q

peneplain

A

ancient erosional surface that used to be a mountain

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17
Q

why are cratons geologically complex

A

made of different geological provinces, which are areas of distinct geology. each represents an ancient microcontinent (terrane) brought together by plate tectonics. they are welded onto the craton along suture zones.

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18
Q

where are the old and young rocks in cratons

A

oldest in the centre and younger on the margins

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19
Q

why are suture zones important

A

its important to know because they are potential earthquake origins

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20
Q

arctica

A

earliest recognizable north american content.

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21
Q

when did arctica form

A

around 2.5 Ga

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22
Q

southern province

A

consists of sedimentary rocks of the Huronian Supergroup (2.5 - 2.2 Ga). it was deposited along the southern margin of Arctica

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23
Q

earliest glacial deposits

A

diamicites (very poorly sorted), glaciomarine deposits, glaciers on basin margins

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24
Q

Sudbury meteor

A

meteorite biger than 4km in diameter traveling 15km/sec. 60X20 km diameter crator 10km deep, making it the second largest on earth. it contains fragmented rocks, and mineral resources which now is the reason that it is a big mining area now and the big nickel

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25
Q

how do know something is an impact crater (in sudbury)

A

fragmented rocks (Sudbury breccia are angular rocks with varying clasts)
shatter cones (apices of cones point toward impact)
shocked quartz grains (evidence for intense shock)
pseudotachylites (rock fused into glass by shock wave)

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26
Q

why is the Sudbury impact crater elliptical not circular

A

it was originally circular but got deformed during the penokean orogeny (1.7 Ga).

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27
Q

mineral resources from sudbury

A

impact melted the crust creating the sudbury igneous complex. the crust was rich in sulphide ores pentlandite (35%Ni), pyrite, and chalcopyrite

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28
Q

how much of the global nickel supply is produced by canada

A

5%

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29
Q

grenville orogeney

A

1.7 - 1 Ga. it was the collision of north america (laurentia) and south america. this was the final stages of the craton formation. at this point there was a lot of landmass near the south pole, which gave conditions for glaciers to grow

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30
Q

orogenic belts

A

eroded and folded rocks from the shield. Gneisses

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31
Q

how many major ice ages in the past 3 Ga

A

5 or 6

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32
Q

ice age

A

relatively long period of time where the earths surface temperature and atmospheric temperature are reduces that allow for continental, polar ice sheets, and apline glaciers to grow.
one ice age will have several glacial and interglacial periods

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33
Q

what is the most recent ice age

A

late cenezoic ice age (34Ma - present)

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34
Q

what are the two current ice sheets

A

Greenland and Antarctic sheet

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35
Q

cenezoic era time

A

66 Ma to present

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36
Q

quaternary period time

A

2.58 Ma to present

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37
Q

what marks the quaternary period

A

ice ages

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38
Q

glacial periods

A

major ice sheets on continents and lowered sea levels - 20,000 to 25,000 years ago was a peak

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39
Q

interglacial periods

A

restricted ice volumes (just on mountain tops) and raised sea levels - what present time is

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40
Q

interstadial periods

A

warm interval within a glacial period - us now. colder than interglacials

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41
Q

requirements to form glaciers

A
  • temperature low enough to retain snow year-round (high latitude and altitude)
  • sufficient snow (some polar climates are very dry, so glaciers do not develop)
  • for glaciers to build, summer melting and ablation must be less than winer accumulation
  • climate - as climate changes glaciers expand or retreat
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42
Q

how many orbital cycles does glacial periods occur over today

A

20, 40, 100, and 400 ka

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43
Q

how does snow turn into glacial ice

A

when snow refreezed into fern after surviving at least 1 summer melt it becomes glacier ice

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44
Q

orbital cycles

A
  • regular variationsin earths orbit control ice ages
  • calculater by astronomer Milutin Milankovic
  • the cycles have opperated throughout earths history.
  • changes earths distance from the sun and therefore the heat energy from it
  • sometimes cycles constructively interfere, and sometimes cancel eachother out so glacial climate cycles can be somewhat irregular
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45
Q

pongola ice age

A

2.9-2.8 Ga
- sometimes included based on different sedimentological and oxygen isotope data
- diamictite rock in south africa and eswatini

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46
Q

huronian ice age

A

2.4 - 2.3 Ga
- gondwana formation. found in northern ontario. diamictites (lithifies diamicts)

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47
Q

neoproterozoic ice age

A

715 - 547 Ma.
sturtian glacial period (720 - 660 Ma) and marinoan glacial period (654 - 625 Ma)
- glacial deposits found hroughout the world. many have proposed a “snowball earth” which is a very controversial topic in geology. the increased albedo from the snow resulted in a positive feedback loop.
- possible subsequent mechanisms include eruption of supervolcano, reduction in greenhouse gases through chemical weathering of CO2, and changes in solar energy output

48
Q

what are one of the big issues with snowball earth

A

life was restricted to marine organisms that needed photosynthesis, which wouldnt be possible if the oceans were covered by snow

49
Q

precambrain

A

4.54 Ga to 541 Ma
not acknowledges as an eon, era, period, etc…
clumping of the oldest 3 eons, hadean, archaen, and proterozoic

50
Q

edicaran period

A

635 - 541 Ma
found evidence of complex life which before thought didnt happen until the cambrian

51
Q

cambrain period

A

541 - 485 Ma

52
Q

what did the breakup of rodinia allow for

A

increased biodiversity

53
Q

cambrian (sauk) transgression

A

ediacaran (635 - 541 Ma) through ordovician (485 - 444 Ma) periods records an overall rise of sea-level and warming. changes from sandstone upwards into carbonates reflects increasing sea level. this opened shallow-water niches for animals to diversify into

54
Q

oldest possible eukaryotes

A

molecular clock suggests first metazoans could have appeared between 800 to 700 Ma before snowball, but no fossil evidence.
oldest multi-celled embryos are found in the Doushantuo Formation in China, dated to around 600 Ma

55
Q

Metazoans

A

synonym for something of the kingdom animalia

56
Q

ediacaran fossils are found where

A

found worldwide, including newfoundland, australia, and namibia

57
Q

first metazoal fossils

A

discovered by english children in the charnwood forest, england. thought to be cambrian but later realized to be later proterozoic. very different from modern sea pend even though they look the same. This just shows how convergent evolution is real

58
Q

where can some of the oldest animals be found in canada

A

mistaken point, newfoundland. it is a world heratige site where life forms are 575 - 541 Ma. They are from the ediacaran period (635 to 539 Ma)

59
Q

petalonomae

A

petal animals.
- have no feeding structures, organs, stinging cells, or body cavity
- fractal body plan increased surface area
- probably fed by osmosis (osmptrophs)
- these organisms have no modern counterparts and represent a long extinct clade

60
Q

ernietta (peralonome)

A
  • found in shallow water sandstones (common in namibia)
  • lived partially buried under the sediment
  • also thought to be osmotrophic
61
Q

bilaterians

A

have bilateral symmetry. mobility was a new thing, and there was clear evidence they could move. none of them could be assigned to an equivalent modern phylum

62
Q

soriggina

A

has a distinct head and tail, as well as segments but no mouth parts

63
Q

kimberella

A

clear evidence of grazing traces and may have been a stem mollusc

64
Q

parvancorina

A

looks vaguely trilobite like but is not related

65
Q

trilobozoans

A

tri-radial symmetry, hard to classify. they show clear evicence of movement

66
Q

calcifers

A

organisms more complex than stromatolites that produce calcium carbonate skeletons. unclear what phyla they belong to

67
Q

cambrian period

A

541 - 485 Ma

68
Q

cambrian paleogeography

A

before the rockies, western north america was a passive continental margin. a major carbonate reed lay at the margin which was close to the equator.

69
Q

burgess shale

A

collapse of the reef top deposited shallow water fauna in muds at the base of the escarpment. conditions allowed the preservation of soft parts (lagerstatte). shale is 508 Ma, well into the cambrian period

70
Q

what happened to life during the break up of rodinia

A
  • ediacaran fauna die out, possibly from an anoxic event
  • some metazoans survive into the cambrian
  • cambrian “explosion” of life forms
71
Q

when did the cambrian explosion of life start

A

539 Ma

72
Q

what are the possible causes of the explosion of life

A

increased oxygen, or maybe there was an increased carbonate concentration - allowing skeletons to form

73
Q

what is the range of principal animal groups developing

A

530 and 520 Ma

74
Q

burgess shale

A
  • in alberta contains the remains of very strange organisms
  • also exposed near Mt. Watpra in BC
  • extremely rich fossil record of diverse and strange organisms
  • some have little affinity to present day phyla, but many modern phyla are also present
  • weird forms represent early experimentation of evolutionary life in uninhabited niches
75
Q

when was the burgess shale deposited in the cambrian times

A

in the middle cambrian, surrounded by dolomite formations

76
Q

what makes the animals in teh burgess shale complez

A

the fact that they have eyes, mouths, etc

77
Q

who discovered the burgess shale and who owns it now

A
  • discovered by charles walcott in 1909
  • now a UNESCO world heritage site
78
Q

what are some of the creatures found in the burgess shale

A

hallucigenia, anomalocaris, pikaia, and opabinia

79
Q

opabinia regalis

A
  • 5 eyes
  • a proboscis (big sucking tube is its whole thing)
  • no legs
  • segments
  • back and side fins
  • 7 cm
  • affinity to modern phyla is uncertain
80
Q

anomalocaris canadensis

A
  • largest predator in the cambrian (60cm)
  • two eyes on stalks
  • back and side fins
  • no legs
  • now assigned to the radiodonta genera
  • verious fossils that were thought to be animals were actually a part of this - shrimp tail looking fossil and jellyfish/sponge looking one
81
Q

radiodonts

A

highly sucessful and diverse group nnow known to have lived through the deconian period. - spoked teeth
a 2m long aegirocassis benmoulae adapted to filter feed, much like a baleen whale

82
Q

hallucigenia

A
  • lobe-feet animals
  • segmented
  • have mouths
  • spines for protection
  • thought to be ancient onychophorans
83
Q

panarthropods

A
  • the lobopods and radiodonts (spoke teeth) are now thought to be the stem-ancestors of the arthropods
  • modern genomics as well as the burgess and similar fossils help understand how tardigrades,, onychophorans and arthropods are related
84
Q

cambrian fauna includes:

A

marella, yohoia, metaspriggina

85
Q

marella

A

an extinct arthropod similar to a trilobite

86
Q

yohoia

A

has two front appendages and is a clear arthropod

87
Q

metaspriggina

A

an early chordate initially thought to be related to spriggina

88
Q

what type of depostional environment made the burgess shale

A
  • deep marine
  • at the base of an ancient carbonate reef
  • quiet environments
  • the animals either lives in the deep water, or on the edge and they all eventually sell down from the reef top.
89
Q

period of techtonic stability

A

538.8 Ma to 485 Ma

90
Q

what kind of margins were along the east and west coast of cambrian north america and what did it leave

A

divergent margins. this left carbonate and sand deposits in shallow inland seas near the equator

91
Q

another name for Laurentia

A

old North America

92
Q

epeiric seas

A

shallow seas that cover large areas of continents

93
Q

what water bodies were by laurentia

A

shallow seas surrounded and epeiric seas on the craton

94
Q

what happened in the early-mid ordovician (450 Ma)

A

laurentia drifted towards baltica (NW Europe) & gondwana (southern continents), closing the lapetus ocean. the plates then collided repeadely at convergent plate boundaries.

95
Q

what did the collision of laurentia, baltica, and gondwana do?

A

the convergent plates created mountains (Taconic mountains), which provided a lot of clastic sediment input to low areas through deltas

96
Q

clastic wedge

A

thick accumulation of sediment or sedimentary rocks in a lens shape. thin near the mountain front and further inland, and thickens in the middle

97
Q

queenston clastic wedge

A

480 km clastic wedge sediment from the taconic mountains. sediment transported by sea to inland rivers, where huge deltas formed as it prograded westward

98
Q

what is the primary composition of the lower niagara escarpment

A

clastic (from taconic mountains)

99
Q

what is the queenston clastic wedge in the niagara escarpment as

A

Queenston shale, whirlpool sandstone, Grimsby shale, and Thorold sandstone. there is a trend of thinner materials as you go down - walters law

100
Q

whirlpool sandstone

A

clean (no interbeds so no environment change), cross-bedded sandstone. deposited in a river system feeduing a large delta

101
Q

grimsby and thorold formations

A

interbedded sandstones and shales - deposited in a shallow sea. wave ripples and hummocky cross-beds in sandstone indicate waves and storm events

102
Q

when did uplift of the taconic mountains stop and what did this do to sedimentation

A

stopped 430 Ma, cutting off the clastic sediment input. this was the middle silurian times. and there was not a deposition of limestones in clear water, and only some shales

103
Q

what formations were deposited in the middle silurian

A

there was reef formation in this time (tropical and shallow water). the reynales and up was during this time (limestone and dolostone), and any shales were from some mud deposition

104
Q

limestone deposition environments

A

deposited in shallow (<10m) tropical seas. formed at 30N to 30S latitudes with cool to warm climates. there were local patch reeds and extensive carbonate platforms. they are carbonates formed through chemical precipitation and bioclastic debris

105
Q

what makes up the cap rock of the NE

A

ancaster and lockport formation

106
Q

why are the beds of the lockport formation different in thickness

A

different times between interuptions in the deposition rate. one bed is uninterupted, so ancaster had more interuptions

107
Q

ancaster formation

A
  • thin beds
  • highly fractures
  • contains chert nodules
108
Q

gasport formation

A
  • thicker beds
  • fewer fractures
  • less chert
109
Q

why did silurian reefs stop

A

climate became warmer and more arid, so seas regressed exposing the reefs and killed them. this becamr extensive tidal flats (sabkhas)

110
Q

what kinds of sediments formed in the silurian tidal flats

A

evaporites. the shallow, restricted basins were surrounded by fringe reefs. the sea water evaported rapidly, precipitating salts (and other stuff like gypsum)

111
Q

what era was the silurian period in and how long ago was it

A

paleozoic era, 444 to 419 Ma

112
Q

how thick is the salina formation in SW ontario

A

750 m

113
Q

what is the rate of precipitate to evaporite formation

A

1000m of sea water gives about 0.75m of gypsum and 1.37m of salt. means a lot of water had to evaporite to create the salina formation

114
Q

common evaporite minerals

A
  • halite
  • anhydrite
  • gypsum
  • sylvite
  • kieserite
  • bischofite
115
Q

goderich salt mine

A

largest in the world. there is a lense shaped salt deposit spanning all the way to chicago, but they do not have as much under them, and detroit in the middle has to dig through other layers to reach it. this is what makes goderichs so great

116
Q

thickness of paleozoic rocks

A

800 m thick below hamilton. thicken westward into the appalachian basin and eastward into the michigan basins

117
Q

paleozoic strata

A

dip gently (<1 deg) to the SW. the strike is NE to SW< younging to the SW. resilian silurian limestones and dolostones make up the niagara escarpment.

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