Download Geologic History of the Earth Geological History

Geologic History of the Earth
(with emphasis on Manitoba)
Geological History
z
Age of Earth: 4.5 to 4.6 Ga (4.54 Ga)
z Meteorites:
extra-terrestrial rocks
z Moon: Apollo
z
Eons:
z Hadean
z Archean
z Proterozoic
z Phanerozoic
1
Hadean Eon (4.6
to 3.8 Ga)
z
High heat flow and
development of
Earth’s internal
structure
z Manitoba:
~3.8
near Thompson
z NWT:
4.03 Ga
Acasta Gneiss –
felsic
z Australia: 4.4 Ga –
from sediments
Hadean Eon (4.6
to 3.8 Ga)
z
High heat flow and
development of
Earth’s internal
structure
z Oldest
rocks
z Felsic
– low density
/ continents (?)
z Clastic sediments –
hydrosphere
z Celestial
bodies
2
Archean Eon (3.8
to 2.5 Ga)
z
Development of
continental nuclei and
origin of life
z
Lithosphere: mostly 3.2 to
2.5
Archean Eon (3.8
to 2.5 Ga)
z
Development of continental
nuclei and origin of life
z
Lithosphere: mostly 3.2 to 2.5
z
Greenstone belts: thin slices
(<20% of crust) of volcanic
and sedimentary rocks
crosscut by granitic intrusions
z
z
z
z
Early volcanism – ultramafic
flows
Increasingly felsic up
sequence – subaerial
Deformed and
metamorphosed
Granite gneiss terrains:
abundant – granite intrusions
and metamorphic rocks
3
Archean Eon (3.8 to 2.5 Ga)
z
Development of continental
nuclei and origin of life
z
z
Hydrosphere: pillow basalts
Atmosphere: outgassing from
volcanoes – H2O & CO2
z
z
z
Reducing CO2 rich atmosphere
Need ozone (2% free oxygen)
– generate remaining
atmosphere
Biosphere
z
z
Origin of life: extreme
environments
Prokaryotes: lack nucleus and
reproduce asexually; anerobic
(no oxygen)
Archean Eon (3.8 to 2.5 Ga)
z
Atmosphere:
outgassing from
volcanoes – H2O &
CO2
z
z
Reducing CO2 rich
atmosphere
Need ozone (2% free
oxygen) – generate
remaining atmosphere
4
Archean Eon (3.8 to 2.5 Ga)
z
Biosphere
z
z
Origin of life: extreme
environments
Prokaryotes: lack
nucleus and
reproduce asexually;
anerobic (no oxygen)
Proterozoic Eon
(2.5 to 0.544 Ga)
z
Manitoba: Trans
Hudson Orogen:
2.2 to 1.6 Ga –
suture zone
5
Proterozoic Eon
(2.5 to 0.544 Ga)
Stabilization of
continental platforms
and oxidation of
atmosphere
z
z
Lithosphere:
z
z
Higher abundance of
sedimentary rocks than
Archean,
Archean, especially
carbonates
Continents
z
z
z
Stable: similar
thickness and volume
Rifting: brittle and
relatively thick
Similar tectonic activity
as today
Proterozoic Eon (2.5 to 0.544 Ga)
z
Stabilization of continental platforms and
oxidation of atmosphere
z Hydrosphere:
z Well
developed oceans
z Atmosphere:
z Oxidizing
atmosphere – CO2 into carbonates
6
Proterozoic Eon
(2.5 to 0.544 Ga)
z
Biosphere
z
z
z
z
Prokaryotes Æ
eukaryotes
(nucleus)
Single celled to
multicelled
Asexual to sexual
reproduction
By end of
Proterozoic –
explosion of life
Phanerozoic Eon
(544 Ma to present)
z
Modern plate
tectonic period and
expansion of life
7
Phanerozoic Eon
z
Modern plate
tectonic period
and expansion of
life
z
Lithosphere:
z
z
Sediment basins
(southern
Manitoba and
along Hudson
Bay): limestones
and sandstones
Volcanic ash
beds from west
Phanerozoic Eon
(544 Ma to present)
z
Modern plate tectonic period
and expansion of life
z
Hydrosphere:
z
z
Shallow seas through much of
time – cratonic sequences and
epicontinental seas
Glaciations from about 2 Ma to
12,000 years before present
z
Atmosphere:
z
Biosphere
z
z
z
Modern day atmosphere
explosion of life: acquire hard
parts
Transition from marine to
terrestrial
8