GEO 1301 Lecture 16: Midterm 3 Essay Questions
4 Apr 2016
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Sheeted dykes (subvertical cracks, extrude pillow basalts) Massive gabbros: intrusive mafic, molten magma is trapped beneath the earth"s surface and slowly cools into a holocrystalline mass. Mid-atlantic ridge, iceland: subduction zones: island arcs. Partial melting of the mantle+ basaltic crust+ sio2-rich sediments. Pyroclastic flow a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing downslope at great speed. South aegean volcanic arc: subduction zones: continental arcs. Eruption and partially emptied magma chamber collapse along fractures caldera crater lake. Mantle plume is fixed, lithosphere moves creating series of volcanoes. Older volcanoes lithospheric subduction (move underwater) Water is superheated at depth no convection cells, so water doesn"t dink (plugged by cooler water at top) pressure released. Both mantle plume and divergent plate volcanism. Hawaii: explain how atolls are formed. make sure to detail each of the stages of formation, starting w/ volcanism. Darwin"s theory starts with a volcanic island which becomes extinct.
