Early Earth …earliest phase of Earth heating… …near Moon… …first seas… …thin atmosphere of H, CO 2, H 2 O, N 2, CO, NH 3, CH 4 …early bombardment…

Early Bombardment 2 phases? Relative dating

Early Earth began to heat as the last extraterrestrial collisions subsided 1.Rock is a good insulator – stores heat 2.Collisions produced heat that was stored 3.Radioactivity 4.Gravitational contraction Early in Earth History the Planet Developed a Magma Sea billion years ago What is the physical consequence of melting a homogeneous ball of rock?

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

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

Effect of chemical differentiation

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

The “Bow Shock Effect”

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

The continental rifting process

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

Spreading center and subduction zone

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

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”

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

Main Types of Plate Motion Convergent Divergent Transform

Five types of plate boundaries DivergentTransformConvergent Ocean-OceanOcean-Ocean Ocean-ContinentOcean-Continent Continent-ContinentContinent-Continent

Five types of plate boundaries DivergentTransformConvergent Ocean-OceanOcean-Ocean Ocean-ContinentOcean-Continent Continent-ContinentContinent-Continent

Divergent Boundary

Convergent Boundary

Transform Boundary

Modern Earth Pangea 240 million

Origin of India

Hot Spot

Paleomagnetism

Igneous Rocks

Sedimentary Rocks

Metamorphic Rocks

The Rock Cycle