EESA06H3 Lecture Notes - Lecture 4: Rench, Oceanic Trench, Viscosity
3 Mar 2012
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Document Summary
The role of transform faults: iceland: walking over a mid-ocean ridge, magnetic stripes recorded in ocean floor crust and the age of ocean floors, basalt lava flows: fissure eruptions, volcanic activity under glaciers: jokulhlaups, geothermal energy. Oceans only widen(rift) to a certain width then they start to close - subduction. History of continent is dictated by ocean history cooling away from ridge and thickens at sides. It wants to sink back down to the mantle. Combining the information can put a picture of history of mors. Fractures horizontal lines on mors enable ocean floor spreading on a curved earth surface. Dykes result of hot magma intruding into older rock, sheeted. Plumes supply the large amounts of magma. How oceans widen: continuous intrusion of dykes continuous cooling of margins of magma chamber and continuous intrusion of new magma at center symmetrical distribution on each side. Pillow basalt pillowed lava, rounded masses where basalt magma was cooled very quickly.
