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Download IgPetrolFinal07 - Department of Earth and Planetary Sciences
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Francis - 2007 Faculty of Science Final Examination Earth and Planetary Sciences 186-423A Igneous Petrology Examiner: Don Francis No books, notes, communication, etc. allowed! Francis - 2007 Introductory Petrology 186-423A Final Exam Dec 20, 2007 Answer 5 out of the 8 following questions! Each question is worth 20 marks. 1) With the aid of a diagram, write an essay explaining how the olivine – clinopyroxene – quartz liquidus projection can be used to formulate a simplistic genetic model relating the Earth’s peridotitic mantle, basaltic oceanic crust, and granitic continental crust. Go on to explain why basalt is the dominant crustal lithology on all the terrestrial planets. 2) With the aid of diagrams, write an essay explaining the manner in which water dissolves in magmas and its effects on the stability of feldspar. Go on to discuss how these effects may explain the compositional differences between the tholeiitic fractionation trends observed in suites of lavas associated with rifts or hot spots versus the calc-alkaline fractionation trends observed in subduction-related lavas. 3) What is the “Hawaiian Paradox”? Write an essay discussing its implications for the nature of the mantle source(s) for Hawaiian and OIB magmas in general. 4) What is the difference between E and N MORB? Write an essay discussing how these differences arise and their implications for the mantle source regions for MORB, making explicit reference to the results of your trace element calculations in Lab 7. 5) Why is the Earth’s granitoid continental crust generally thought to have been formed by subduction-related processes? What problems do the differences between oceanic island arcs and continental arcs pose for such a hypothesis. What might be the resolution to this dilemma. 6) What do our analyses of Martian basalts and the Shergotiite meteorites tell us about the igneous petrology of Mars? 7) Discuss the differences between hypabyssal and diatreme facies kimberlite, making explicit reference to your results from Lab 10. Go on to discuss the process(s) responsible for these differences. 8) Discuss the relationship between plutonism and volcanism in continental calc-alkaline suites making explicit reference to your results for Labs 8 and 9 on Eocene magmatism of the northern Canadian Cordillera.
