Lithosphere slides past; not created or destroyed.
Many transform offset spreading ridge segments Characterized by Earthquakes and Absence of volcanism
Oceanic Transforms: Offsets along the MOR (Mid-Ocean Ridge)
Older interpretation, faulting occurs after MOR. Modern interpretation, faulting occurs with MOR.
Continental Transform Boundaries in ex. San Andreas Fault
Special Places in the Plates (Earth’s Surface)
Triple Junction: Point where 3 plate boundaries intersect
Multiple Boundary combinations occur
Stable vs Unstable
Hot Spots: Hot spots perforate overriding plates and as a result, volcanoes build above the sea level. Plate motion pulls volcano off plume
Goes off extinct and erode
Hot spots reinforce sea-floor spreading
What drives plate motion?
Old idea: Plates are dragged atop a convecting mantle Plate motions are much too complex
Convection does occur; not the prime during mechanism Modern Thinking: Two other forces drive plate motions
Ridge push - elevated MOR pushes lithosphere away Slab pull – Gravity pulls a subducting plate downward Plate Velocities: Absolute plate velocities may be mapped by: Plotting plate motion relative to a fixed spot in the mantle which measure the HOT SPOT TRACK.
Minerals – The Building Block of Rocks
Minerals – Now studied using high-tech instruments Probe the atomic structure of minerals
X-Ray diffractometers – Same principle as in 1915 Electron microscopes and microprobes Mass spectrometers
Minerals are the building blocks of the Earth’s Crust
Are important natural resources from which many of our material goods are manufactured Money$$$...