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Unformatted text preview: ultramafic to felsic rocks?  P LATE T ECTONICS AND THE E ARTH S C RUST [10+10 = 20 points] Oceanic and continental crust crystallize from magma generated in the mantle beneath spreading ridges and subduction zones, respectively (Figure 1). How does the temperature in the source region compare between the two types of crust?  Komatiite, an ultramafic volcanic rock, has been virtually extinct for about 2.5 billion years, but before that, commonly occurs with basalt in geological settings where basalt alone is found today. Granitic rocks more than three billion years old generally are gray, colored by sodium feldspar, whereas those formed later are generally pinkish, colored by potassium feldspar. Again considering Bowens Reaction Series, what could account for both of these changes? ...
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This note was uploaded on 09/24/2011 for the course EAS 1560 taught by Professor Monger during the Spring '09 term at Cornell University (Engineering School).
- Spring '09