Geology 115/History 150Name:
Geology Prep Assignment 6:Minerals and metamorphic rocks
Due Tuesday, May 10
Your borrowed textbook ought to cover both topics, but there are some good notes out there, such as:
1. What is the difference between a mineral and a rock?
2. Why aren’t the hardest minerals (e.g., diamond) shatterproof?
3. The three principal types of metamorphism that you will see in the rest of this assignment are blueschist(or subduction-zone) metamorphism, contact (or thermal) metamorphism and regional (or dynamothermal) metamorphism. Using combinations of the phrases “high pressure”, “low pressure”, “high temperature”, “low temperature”, describe each of the three types of metamorphism.
Yellowstone NP: Van Gosen, Bradley S., The Life Cycle of Gold Deposits Near the Northeast Corner of Yellowstone National Park – Geology, Mining History and Fate, US Geological Survey Professional Paper 1717 (2007)
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4. “Skarn” is mentioned quite a lot in the publication; it’s the second word in the introduction. From context, it seems to be a rock. From a different source, determine what type of rock skarn is, and how it is made.
5. When, geologic timescale-wise, were the gold-copper-silver minerals emplaced in the New World district? What other geologic activity was this emplacement associated with? Hint: p. 436
6. On pages 445-446, there is a seven-step history of the gold-copper-silver mineral emplacement. Based off your definition of “skarn”, what material in step 5, the “massive ore-deposit formation” step, played a crucial role? What did it do, or, better, what was done to it?
7. Finally, which of the three types of metamorphism mentioned in question 3 did this area near Yellowstone NP undergo?
Rocky Mountain NP: National Park Service, Rocky Mountain National Park Geologic History
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8. Look for metamorphic rock names in the history, and determine in what geologic period of time the metamorphism of these rocks took place. Did later orogeniesand glaciations alter these metamorphic rocks further?
9. Which of the three types of metamorphism mentioned in question 3 did this area undergo? Hint: If you really need help:
North Cascades NP: US Geological Survey, “Terranes of the North Cascades: Easton Terrane” (2014)
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10. Clearly, this area must represent the third type of metamorphism, not seen in the other two national parks. What type of metamorphism is this, and what evidence for this type of metamorphism does the author of this page state?
11. What is a “terrane”, and how is this term consistent with this type of metamorphism?