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Proterozoic Making the Modern World
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2500-543 Myrs 2500 Myr 1600 Myr 1000 Myr
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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 Cratons: Shields 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 Orogeny 1.2-1.0 Gyrs
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Rodinia “Motherland” Forms 1.2-1.0 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 a Failed Rift
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Continental Rift
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Keweenawan Supergroup, MI Mesoproterozoic Rift Rocks
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Rodinia Rifts (750 Myrs) Montana New York Rifts to form the (pre-Pacific) Panthalassa Ocean Rifts to form the (pre-Atlantic) Iapetus Ocean
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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 Changes Oxygen Increases: Carbon Dioxide Decreases Proterozoic Thanks to…
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BIF’s (3.5-1.8 Gyrs) Banded Iron Formation 92% Between 2.5-2.0 Gyrs
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Iron Source: Hydrothermal Vents
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Carol Lake Iron Mine, Canada
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Red Beds <1.8 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 Changes: UV 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 Varves The First Ice Age
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Major “Ice Ages” in Earth History 1 2 3 4 5
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Glacial Evidence from Neoproterozoic Rock for Varangian Ice Age
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Neoproterozoic Snowball 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) Tillite Carbonates & Ironstones
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Snowball Earth
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12 C 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?
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