1. Rodinia, Rifting, Iapetus and the Great American Bank

2. General Structure of Continents
Shields – old, tectonically stable foundation of continent
Cratons – parts of shield with thin cover of sedimentary rocks
Passive Margins – continental shelves, mid-plate
Convergent Margins – zones of subduction and collision at edge of plate

3. Precambrian Shield Predominantly crystalline (granite & gneiss)
Divided into “Provinces” by age and structureal “grain”
Provinces represent the roots of long gone mountains
Each Province produced during a specific Orogeny
Narrow greenstone belts
Commonly between provinces
Metamorphosed mafic volcanics
Ophiolites
Immature sedimentary rocks
Remnants of subducted oceanic lithosphere

4. The Grenville Province
Last Precambrian Orogeny in North America Ga
Regional metamorphism from Maritime Canada to Georgia
Last event in the assembly of the supercontinent Rodinia

5. Grenville Gneiss

6. Assembling Rodinia: the Grenville Orogeny

7. Rodinia – a supercontinent 700 Ma before Pangea

8. Potsdam (C) – Grenville (Pre-C) Nonconformity in New York

9. Precambrian – Cambrian Nonconformity - Colorado

10. Precambrian – Cambrian Nonconformity – Grand Canyon, AZ

11. Precambrian – Cambrian Nonconformity
Widespread across North America
Extensive erosion of shield and Grenville Orogen (Mountains)
Worldwide Transgression in Latest Precambrian into Cambrian
Similar pattern on other continents
Post-unconformity rocks are Quartz Arenites and Limestones
Typical cratonic association

12. Rifting Rodinia – Opening the Iapetus Ocean, Birth of the Great American Bank

13. Great American Bank Opening of Iapetus Ocean Creates passive margin
Thermal subsidence produces accommodation space
Thousands of meters of quartz arenites and limestones/dolomites deposited in shallow water
Stromatolites, Mudcracks, Intraclasts
Exposed in Cumberland/Great Valley and Shenandoah Valley
Sequence is thinner in New York
more inboard position – less subsidence

14. Wading in Iapetus - Stromatolites

15. Wading in Iapetus – Quartz Arenites, Limestones, Burrows & Ripples

16. Great American Bank Carbonates – Mohawk Valley, New York