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Early Earth

Early Earth

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Early Earth

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  1. Early Earth …early bombardment… …earliest phase of Earth heating… …thin atmosphere of H, CO2, H2O, N2, CO, NH3, CH4 …near Moon… …first seas…

  2. Early Bombardment2 phases? Relative dating

  3. Early in Earth History the Planet Developed a Magma Sea 4.5-4.0 billion years ago • Early Earth began to heat as the last extraterrestrial collisions subsided • Rock is a good insulator – stores heat • Collisions produced heat that was stored • Radioactivity • Gravitational contraction What is the physical consequence of melting a homogeneous ball of rock?

  4. Temperature reached melting point • of iron: • Liquid iron flowed inward • Friction raised temperature • Liquid Silicon and Oxygen flowed • outward (Ca/Na/Al/K) • “Iron Catastrophe” • Planet became chemically • differentiated

  5. Inner core – Fe/Ni solid • Outer core – Fe/Ni/Mg liquid • Mantle – Fe/Mg solid rock • capable of flow • Lithosphere – Fe/Mg/Si/O • Lower lithosphere - Fe/Mg • Crust – Si/O/Fe/Mg/Ca/Na/K/Al • Oceanic crust – Fe/Mg/Ca • Continental crust – Si/O/Na Increasing Fe/Mg toward core Increasing Si/O toward crust

  6. Effect of chemical differentiation

  7. Earth’s magnetic field emanates from the core complex and surrounds the planet. Magnetism gained from early nebula is magnified by turbulent iron, nickel fluid of outer core. Magnetic field envelops entire planet Polarity +- tends to reverse and fluctuate with time

  8. The “Bow Shock Effect”

  9. Another consequence of differentiation is convection. How does convection work? How will the lithosphere respond to a plume?

  10. The continental rifting process

  11. Mid-Ocean Ridge Spreading Center But if you keep making crust the Earth must be expanding! Right?

  12. Spreading center and subduction zone

  13. Global Tectonics Partial Melting Partial melting is responsible for evolving mantle rock… among other things this gives us continents.

  14. Oceanic lithosphere – general chemistry is Fe, Mg, Ca, Si, O in the form of a rock “Basalt” Continental lithosphere – general chemistry is Si, O, Al, Na, K…in the form of a rock “Granite”

  15. “Ridge Push” “Slab Pull” Plate Movement “Plate Drag”

  16. Convergent Divergent Transform Main Types of Plate Motion

  17. Five types of plate boundaries • Divergent • Transform • Convergent • Ocean-Ocean • Ocean-Continent • Continent-Continent

  18. Five types of plate boundaries • Divergent • Transform • Convergent • Ocean-Ocean • Ocean-Continent • Continent-Continent

  19. Divergent Boundary

  20. Convergent Boundary

  21. Transform Boundary

  22. Pangea 240 million Modern Earth

  23. Origin of India

  24. Hot Spot

  25. Paleomagnetism

  26. Igneous Rocks

  27. Sedimentary Rocks

  28. Metamorphic Rocks

  29. The Rock Cycle