Proterozoic
Making the Modern World
2500-543 Myrs
Era Age (Myrs) Epoch
0.01Holocene
1.8Pleistocene
5.3Pliocene
23.8Miocene
33.6Oligocene
54.8Eocene
65Paleocene
144
206
248
290
323
354
417
443
490
543
2500
3800
Precambrian
Phanerozoic
Eon
Proterozoic
Archean
Hadean
Period
Quaternary
Tertiary
Neogene
Paleocene
Mississippian
Cenozoic
Mesozoic
Paleozoic
Cretaceous
Jurassic
Age of the Earth 4600 Myrs (4.6 Byrs)Source: Geological Society of America (1999)
Geologic Time Scale
Devonian
Silurian
Ordivician
Cambrian
Triassic
Permian
Pennsylvanian
2500 Myr
1600 Myr
1000 Myr
Rocks of the Proterozoic& the Stories They Tell
Anatomy of a Continent
Orogenic(Mobile) Belt
Basement Rock
Precambrian Cratons:Shields and Platforms
CratonsShields
AndPlatforms
Orogenic (Mobile)
Belts
Orogenies= Mountian Building Events
Caused by:1. Collision - Fold and Thrust Mountains
Orogenies= Mountian Building Events
Caused by:2. Subduction - Volcanic (Arc) Mountains
Provinces of the NA
CratonA.K.A.
“The United Plates of
America”
Archean Basement
Proterozoic Basement
Orogenic (Mobile) Belts
Continental Growth
Proterozoic
Radioactive Heat Flow
Proterozoic
Grenville Orogony
(The building of Rodinia)
Archean Basement
Proterozoic Basement
Orogenic Belts
Rocks of the Grenville Orogeny1.2-1.0 Gyrs
Rodinia“Motherland”
Forms1.2-1.0 Grs
Montana
New York
Belt Supergroup, Montana West Coast of Laurasia
Mid Continental
Rift(1.3-1.0 Gyr)
Origin of aFailed Rift
Keweenawan Supergroup, MIMesoproterozoic Rift Rocks
RodiniaRifts
(750 Myrs)
Montana
New York
Rifts to form the (pre-Pacific) PanthalassaOcean
Rifts to form the (pre-Atlantic) Iapetus Ocean
Rifting of Rodinia
Gondwana & Laurentia
About 500 Myr
Atmospheric ChangesOxygen Increases: Carbon Dioxide Decreases
Proterozoic
Thanks to…
BIF’s(3.5-1.8 Gyrs)
Banded Iron Formation
92% Between2.5-2.0 Gyrs
Iron Source:Hydrothermal Vents
QuickTime™ and aVideo decompressor
are needed to see this picture.
Carol Lake Iron
Mine, Canada
Red Beds<1.8 Gyrs
After iron in the ocean was used up, it started to
accumulate in the atmosphere.
Oxygen Buildup occurs at the Same
Time as First Eukaryotes Appear
Atmospheric Changes:UV Protection
Reduced Amounts of Carbon Dioxide Made it Possible for…
Paleoproterozoic (2.2 Gyr)Gowganda Fm, Canada
Tillite
VarvesThe First Ice Age
Major“Ice Ages”
in Earth History
1
2
3
4
5
Glacial Evidence from Neoproterozoic Rock for Varangian Ice Age
NeoproterozoicSnowball Earth
Where Did All the Atmospheric Carbon Dioxide Go?
The Carbon Thermostat
Neoproterozoic (Varangian)Ice Age (800-600 Myr)
Tillite
Carbonates &
Ironstones
12C Signature
in Snowball Deposits
Carbon Isotopes & Snowball Earth
Why Banded Iron
Formations?
Ice Age Ends at the Same Time the First Multi-Celled Animals
Appear
Coincidence or not?