intro_to_geo_5 - Plate tectonics cont Mid-ocean Ridge...

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Plate tectonics cont Mid-ocean Ridge Mid-ocean ridges are elongate, relatively narrow chains of basaltic volcanoes that traverse the ocean floor, rising to a relief of 2 to 2.5 km above the surrounding abyssal plain In some cases, a narrow axial trough runs down the center of the ridge The high-heat flux at the ridge melts mantle material to form magma, which is relatively light and rises to the surface Some of the magma crystallizes beneath the surface (as gabbro or in thin basaltic dikes ) Some erupts to form volcanic lava, which flows and ultimately solidifies to form pillow basalt Age of ocean sediments Sediments atop oceanic basalts become thicker with increasing distance from midocean ridges as spreading continues The lower-most (oldest) layers become progressively older with increasing distance from the ridge as well Oceanic vs. continental lithosphere The crustal part of the oceanic lithosphere is thinner, more mafic (largely basalt), and more dense, compared to the granitic and thicker crust of the continental
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This note was uploaded on 04/08/2011 for the course GEOL 2001 taught by Professor Babaie during the Winter '09 term at University of Georgia Athens.

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intro_to_geo_5 - Plate tectonics cont Mid-ocean Ridge...

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