Earth Sciences 1022A/B Chapter Notes - Chapter 3: Magma Chamber, Igneous Rock, Geothermal Gradient
22 Sep 2012
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Document Summary
Form from molten material magma (less dense than rocks) Magma is formed through process partial melting: occurs at various levels of crust and upper mantle. Magma that reaches earth"s surface = lava, melted portion = melt, solid = silicate minerals forms at surface: extrusive / volcanic. Sometimes loses mobility before reaching surface, igneous rock forms at depth intrusive / plutonic: occurs in bc. Primary magma: from direct melting of rocks, has not evolved yet. Geothermal gradient, hotter deep in the earth. Increase in confining pressure causes rise in rock"s melting temperature. Decompression melting is triggered where confining pressure drops. When rock goes up from convective upwelling, moves into zones of lower pressure, thus melts generates magma along ocean ridges where plates are drifting apart. Volatiles rock"s water content can affect rock to melt at lower temperatures. Wet rock has lower melting temp than dry. Magma due to lighter density, rises through volcano. Volcanoes came from ancient god of fire, volcan.
