EESA06H3 Lecture 4: EESA06 Lecture 4.pdf
Document Summary
Topics for lecture 4 and for quiz 3 on thrusday feb 10th. Introduction to mid-ocean ridges: modern and ancient fossil mors (called ophiolites) 3: 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 cooling away from ridge and thickens at sides. It wants to sink back down to the mantle. History of continent is dictated by ocean history. 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 dykes - surrounding rock will be extended basic fuel behind plate tectonics. Plumes supply the large amounts of magma.
