GEOL 1050 Lecture 4: CHAPTER 4 LECTURE
Document Summary
Tectonic plates are fragments of lithosphere: lithosphere is made of both crust and the upper mantle, the lithosphere is in motion over the asthenosphere. Plates move continuously at a rate of 1-15 cm/year: slow on a human time scale; extremely rapid geologically. Locations of earth where tectonic plates meet: identified by concentrations of earthquakes, associated with many other dynamic phenomena. Where land meets the ocean: margins near plate boundaries are active , margins far from plate boundaries are passive . Passive-margin continental crust thins seaward: transitions into oceanic crust, traps eroded sediment, develops into the continental shelf. Divergent boundary tectonic plates move apart: lithosphere thickens away from the ridge axis, also called: spreading boundary, mid-ocean ridge, ridge. Lava (basalt) comes out (some of the highest temp lava) Black smokers are found at some mors: water entering fractured rock is heated by magma, hot water dissolves minerals and cycles out of rock, when water reaches the sea, minerals precipitate quickly.
