EESA06H3 Lecture : Lecture 2
Document Summary
Collisional (obducting and subducting) margins and divergent (ridges) Are actually volcanoes (shallow water) or ocean crust/floor. A lot of volcanic and biological activity. l k z in rocks as it rises up and cools on the ocean floor: e. g. nickel, silver, copper, lead, 2. Harold hess introduced idea of sea floor spreading (1962) Oceanic crust spreads and pushes into subduction zones. Basalt in crust gets melted and mixed to become magma. Magma get less dense and will want to push up. The younger the ocean, the hotter the basalt, oceans are shallowest at the middle portion (ridge) as material is being recycled. Older oceans have more dense rocks, so they are deeper. Continental crust is the result of the subduction, melting of oceanic crust plus sea water. The whiter (more silica) the lighter/less dense it is. A lot of magnetic particles in the magma that are free to rotate but will point to the north pole.
