Igneous_Rocks_HW_latest

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Dec 6, 2023

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GG 101L NAME Chloe Yoshihiro Semester: Spring 2022 SECTION (Weekday and time) Tuesdays (1:30-4:20) Homework #3: IGNEOUS ROCKS Homework: Read Chapter 3 and answer the following questions (this homework is due at the start of the Igneous Rocks lab) 1. What are the three major rock types? ______sedimentary_______ ______igneous_______ ____metamorphic_____ 2. Can an intrusive rock have the same chemical composition as an extrusive rock ? ___yes____ 3. How is gold related to igneous activity? Hot magmas drive the circulation of a lot of hot water. These hot fluids pick up several important metals and can deposit them to create metal ore deposits. 4. What does porphyritic texture tell you about the cooling history of an igneous rock? A porphyritic texture suggests an initial period of slow cooling followed by faster cooling. 5. How does a welded tuff form? A welded tuff forms when ejecta is hot enough when it lands, and the particles are soft and sticky. The ejected particles are welded together. The deposits may be near the vent and welded together. 6. What is the fine-grained equivalent of gabbro? _Basalt (Vesicular, porphyritic)_ 7. What is the coarse-grained equivalent of rhyolite? _Granite (Porphyritic)_ 8. What is the most abundant igneous rock in the Earth’s crust? __Basalt__ 9. What is the most abundant igneous rock in the Earth’s mantle? __Peridotite__ 10. What does an olivine with a rim of pyroxene tell you about the history of the olivine? The olivine crystallized first, and at higher temperatures, and as the magma cooled, pyroxene formed around the olivine crystals. 11. Would you expect to find Ca-rich or Na-rich plagioclase feldspars in a mafic rock? Ca-rich plagioclase feldspars
12. Would all the minerals in a granite melt at the same time if you heated the granite slowly? No, there are many minerals within granite, however, most of the minerals within granite would melt first. 13. What minerals in the granite would you expect to melt first? Biotite and Potassium Feldspar. 14. What is one reason why you might expect the composition of magma erupted at a convergent plate boundary to be different from that erupted at a divergent plate boundary? Magma below a divergent plate has less types of material to get through than magma below a convergent plate boundary. There is more material that the magma can interact with under a convergent plate boundary, therefore yielding varying compositions of magma. Magmas formed by partial melting may interact with a variety of rocks to produce abundant intermediate and felsic magmas. Spend some time looking over the supplementary reading on Laulima if you want the igneous rocks lab to be a lot easier.
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