GEOL 1010 Lecture 6: Geology notes 10:4
4 Oct 2016
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Plate tectonics: old ocean basins vs new ocean basisns. Plates composed of crust overlying cold" mantle that sits on hotter mantle (asthenosphere) Moho = location where the velocity of seismic wave changes (more later) Uplift and fracturing of crust upwelling mantle. Board upwelling of a region of continental crust leads to a region of thin crust. Decreases pressure on underlying asthenosphere results in partial melting all different types of rocks show up in this area. New material is injected by rising ultramafic rocks that melt due to decomposition. The alvin based out of wood hole oceanographic. An atlantic-type margin termed a passive margin: no major seismicity. The lithosphere thickens away from the ridge as heat is lost. Mantle rock freezes" onto the bottom of the crust. So older plate = thicker plate = deeper the ocean above: first noticed by darwin in the pacific (fig 9. 34, confirmed by radiometric dating of volcanics.
