Earth Sciences 1022A/B Lecture Notes - Lecture 8: Mantle Plume, Oceanic Basin, Continental Margin

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1022A/B
• Professor: Stephen R Hicock

Document Summary

Continents rise above oceans due to isostasy buoyant continental lithosphere floats on dense asthenosphere; thicker lithosphere, higher mountains with deeper roots mountain-building processes are collectively called orogenesis. Mountains and plate tectonic environments (margins): mountain (orogenic) belts parallel plate boundaries in three main settings of continental margins. Divergent: mantle plume rises, uplifts, and splits continental lithosphere to form rift valley with blocks dropped along normal faults, and volcanoes along valley sides, continental lithosphere uplifted, splits over mantle plume rift valley, volcanoes along sides. Oceanic crust subducts under continental crust, forming accretionary wedge, continental volcanic arc andesitic to granitic plutons. Oceanic crust subducts under oceanic, to form. Foreign crustal fragments stuck onto margin: wilson cycle oceans opened and closed, mountains built and rebuilt repeatedly; rarely pieces of oceanic crust got stuck onto continental margin during obduction. Uplift: mantle upwelling pushes up continental lithosphere in continent interiors.