Proterozoic

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Proterozoic

• Making the Modern World

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1000 Myr
1600 Myr
2500 Myr
2500-543 Myrs
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Precambrian
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Rocks of the Proterozoic the Stories They Tell
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Anatomy of a Continent
Orogenic (Mobile) Belt
Basement Rock
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Precambrian CratonsShields and Platforms
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Cratons
Shields And Platforms
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Canadian Shield
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Orogenic (Mobile)Belts
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Orogenies Mountian Building Events
Caused by 1. Collision - Fold and Thrust
Mountains
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Orogenies Mountian Building Events
Caused by 2. Subduction - Volcanic (Arc)
Mountains
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Provinces of the NA Craton
A.K.A. The United Plates of America
Archean Basement
Proterozoic Basement
Orogenic (Mobile) Belts
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Continental Growth
Proterozoic
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Radioactive Heat Flow
Proterozoic
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Grenville Orogony(The building of Rodinia)
Archean Basement
Proterozoic Basement
Orogenic Belts
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Rocks of the Grenville Orogeny1.2-1.0 Gyrs
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RodiniaMotherlandForms1.2-1.0 Grs
Montana
New York
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Belt Supergroup, Montana West Coast of Laurasia
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Mid Continental Rift(1.3-1.0 Gyr)
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Origin of aFailed Rift
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Continental Rift
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Keweenawan Supergroup, MIMesoproterozoic Rift
Rocks
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RodiniaRifts(750 Myrs)
Rifts to form the (pre-Pacific) Panthalassa Ocean
Montana
Rifts to form the (pre-Atlantic) Iapetus Ocean
New York
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Rifting of Rodinia
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Gondwana Laurentia
About 500 Myr
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Wilson Cycle
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Atmospheric ChangesOxygen Increases Carbon
Dioxide Decreases
Proterozoic
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BIFs(3.5-1.8 Gyrs)Banded Iron Formation
92 Between 2.5-2.0 Gyrs
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Iron SourceHydrothermal Vents
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Carol Lake Iron Mine, Canada
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Red Bedslt1.8 Gyrs
After iron in the ocean was used up, it started
to accumulate in the atmosphere.
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Oxygen Buildup occurs at the Same Time as First
Eukaryotes Appear
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Atmospheric ChangesUV Protection
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Reduced Amounts of Carbon Dioxide Made it
Possible for
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Paleoproterozoic (2.2 Gyr)Gowganda Fm, Canada
Tillite
The First Ice Age
Varves
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MajorIce Agesin Earth History
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4
3
2
1
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Glacial Evidence from Neoproterozoic Rock for
Varangian Ice Age
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NeoproterozoicSnowball Earth
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Carbon Storage
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Where Did All the Atmospheric Carbon Dioxide Go?
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The Carbon Thermostat
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Neoproterozoic (Varangian)Ice Age (800-600 Myr)
Carbonates Ironstones
Tillite
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(No Transcript)
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Snowball Earth
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12C Signature in Snowball Deposits
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Carbon Isotopes Snowball Earth
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Why Banded Iron Formations?
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Ice Age Ends at the Same Time the First
Multi-Celled Animals Appear
Coincidence or not?