Plate Tectonics and Transform Boundaries

Plate Tectonics

• Plate tectonics is a scientific revolution
• Three types of tectonic plate boundaries exist, based on relative motion
• Transform plate boundaries are special locations in the tectonic plate mosaic

Transform Plate Boundaries

• Transform plate boundaries are where plates slide horizontally past each other
• The Pacific plate has three major transform boundaries: Queen Charlotte, San Andreas, and Alpine fault.
• The San Andreas Fault in California is a prime example
• The San Andreas Fault is a source of water for San Francisco.

Spreading Ridges and Fracture Zones

• Spreading ridges are broken up by fracture zones.
• Fracture zones are transform faults that cut across the oceanic ridge.
• Earthquake activity at ridges indicates sliding movement
• Transform faults occur between axes of mid-ocean ridge segments

Transform Faults

• Transform faults are contacts between plates that slide horizontally
• They commonly connect two mid-ocean ridges.
• Transform boundaries often occur along mid-ocean ridges, separating two tectonic plates.

Triple Junctions

• The intersection of three tectonic plates forms a triple junction
• There are different types of triple junctions, such as ridge-ridge-ridge.

Hotspot Volcanoes

• Hotspot volcanoes are not plate boundary volcanoes
• A chain of seamounts is formed by a hotspot
• Magma upwelling produces a hotspot.
• As the plate moves, the volcano moves away from the hotspot, and is eventually eroded.

Volcanic Ages of Seamounts

• Volcanic ages of seamounts increase away from the Hawaiian Islands.
• As the Pacific plate moves over the Hawaiian hotspot, volcanoes are created at different points in time and at varying distances from the hotspot.

Iceland

• Iceland is one of the most active volcanic regions.
• Specific features indicate the focus of the mantle plume.
• Specific zones and periods of activity are important indicators of Iceland's volcanic history and activity.