Plate Tectonics

Plate

a rigid unit of lithosphere that moves as a unit

Lithosphere is made up of

crust + upper rigid mantle

Who proposed the "Continental Drift Theory"?

Alfred Wegener

Proof of Continental Drift

Coastlines
Fossils (similar plant fossils)
Geology (rock formation)
Paleomagnetism

Geodynamo

heat-driven circulation of liquid iron in Earth's fluid core

What is believed to produce Earth's magnetic field?

geodynamo

Seafloor Magnetic Stripes

when molten rock solidifies and cools, iron bearing minerals become oriented to the magnetic field of the Earth

3 Types of Seismic Waves

Primary (P-waves)
Secondary (S-waves)
Surface

Primary Waves (P-waves)

compressional waves that are longitudinal in nature

Secondary Waves (S-waves)

shear waves that are transverse in nature (up and down)

Surface Waves

occur when body waves reach the surface
move up and down as well as side to side

Isostatic Equilibrium (Theory of Isostasy)

lithosphere's elevation depends on its thickness and density
this process maintains this equilibrium by adding or removing weight

Types of plate boundaries

Divergent
Convergent
Transform

Divergent Boundary Examples

Rift Valley in Africa (continental-continental)
Mid-Atlantic Ridge (oceanic-oceanic)

Convergent Boundary Examples

Mt. Rainier (ocean-continent)
Himalayan Mtn. (continent-continent)

Transform Boundary Example

San Andreas Fault

Which boundary generates new crust?

Divergent

Subduction

occurs when an oceanic plate runs into a continental plate and slides beneath it

Obduction

the sideways and upwards movement of the edge of a crustal plate over the margin of an adjacent plate

Ring of Fire

A belt of increased volcanic activity that rings the pacific ocean

Mantle Plume

sustain long-lasting volcanic activity

Hotspot

an area, often far from the edge of a tectonic plate, where magma has risen up through the crust

Best known hotspot under the North American continental crust

Yellowstone National Park

Wilson Cycle

describes the opening and closing of ocean basins as well as the subduction and divergence of tectonic plates

Hydrothermal Vents

fissures on the seabed from which geothermally heated water discharges

Initial Evidence for Hydrothermal Systems

How is magnesium removed from seawater?

Why is Mn so abundant in deep sea sediments?

Gap in heat budget

How do hydrothermal vents form?

sea water percolates down through fissures in the ocean crust near spreading centers or subduction zones

cold seawater is then heated by magma

Types of Hydrothermal Vents

White smokers

Black smokers

White Smokers

emit lighter-hued minerals (such as barium, calcium, and silicon) and tend to have lower temperature plumes

Black Smokers

found in abyssal zones

typically emit particles with high levels of sulfur-bearing minerals

Chemosynthesis

Energy released by oxidation used to form organic matter

Organisms on Hydrothermal Vents

Tubeworms

Pompeii Worms

Tubeworms

no mouth, eyes, or stomach

symbiotic relationship with the billions of bacteria that live inside them

Pompeii Worms

reside in hotter water

covered in a “fleece” of bacteria

How do we know the temperature of pure hydrothermal fluid?

End-member Mixing Model