GEL 1 Lecture Notes - Lecture 9: Mid-Ocean Ridge, San Andreas Fault, Eurasian Plate
sediment melting produces the island arcs and volcanic arcs - the birthplace of continents
●felsic volcanism
Motion of Indian plate over past 70 my
●used to be in SE part of africa, moved,rotated, and collided w asia 10 mya
●himalayas relatively young
○rockies and appalachians older
●subduction of oceanic crust under eurasian plate.
●10 mya, continental portion of indian plate collided w/ continental portion of
eurasian plate, which stopped the melting/volcanism because no more subducting
oceanic crust
○suture
■boundary is technically still there but land is fused like @ appalachian
mountains
●historic earthquakes along continent-continent convergent margin
Divergent Boundary
●continental rifting and the birth of Ocean Basins
○East Africa is a continental rift system
○Red sea, and other rift zones filling w water
○shallow mantle (asthenosphere) → volcanism associated w/ divergent
boundaries
■not super explosive, but a lot of volcanic activity because mantle is very
close to surface
●formation of a new ocean basin after continental rifting
○mantle material rising (upwarping the land), crust pulls apart and thins
○as those continue to pull apart, becomes below sea level and fills w/ water
■South America and Africa
■East Africa right now
○mid ocean ridge and rift valley
●split original plate into two new plates
San Andreas Fault - Transform/Transverse Plate boundary
●plates sliding past each other
●connects divergent boundary in Gulf of Calif. w/ convergent boundary along Cascades
margin
●another example: Alpine fault in South Island of New Zealand
●right-lateral strike-slip fault
Transverse Plate boundary
●Strike-Slip Fault
○left-lateral
○right-lateral
■facing north, if plate on right is moving toward you, and plate on left is
moving away
■or, on one side of the fault, the other side is moving right
Document Summary
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