Homework #8 - (2). Assume the melt flows into a new magma...

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Exercise #8 Due BEFORE CLASS on November 22nd, 2010 Rules: You may use any reference you would like. You are encouraged to help each other, but please write your own answers. Remember, no late work is accepted. For questions 1 and 2, use figure 5.10a on p. 83 of your text to answer the following questions. Assume equilibrium crystallization. For question 3, use figure 5.23 on p. 92. (1). Assume that you have a plagioclase mineral under P H2O = 5 kbar that starts to melt at 900°C. • What is its chemical composition? • What is the composition of the first melt to form? • What is the composition of the last solid to melt? • What is the composition of the solid after 50% of it has melted?
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Unformatted text preview: (2). Assume the melt flows into a new magma chamber after exactly half of the solid has melted. What is the composition of this melt? What is the composition of the first solid to crystallize from this new melt? What is the composition of the crystals once the entire magma chamber has crystallized? What is the temperature when the final melt crystallizes? (3) Assume you have an alkali feldspar with a composition of Ab 70 At what temperature does exsolution start? At 400 degrees, what are the compositions of the two exsolution minerals? At 400 degrees, what are the percentage fractions of the two minerals that have exsolved? 1...
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