1) Using Figure A, what is the temperature of the rock inside the Earth at a depth of 100 km
a) in a normal situation
b) at a divergent plate boundary (mid-ocean ridge)
c) at a convergent plate boundary (subduction zone)
2) Why do the temperatures of the rock inside the Earth at 100 km differ from the normal situation at mid-ocean ridge? What is going on there to cause this difference? Hint: look at the diagram below the graphs in Figure A to help you answer this. Do not copy from the internet for this answer.
3) Why are the temperatures of the rock inside the Earth at 100 km similar in a normal situation and at a convergent plate boundary? Hint: look at the diagram below the graphs in Figure A to help you answer this. Do not copy from the internet for this answer.
4) What is the shallowest depth at which melting occurs at a divergent plate boundary according to Figure C above? Look at the solidus (melting curve) and the geotherm to determine this.
.9) The melting temperature of mantle rock at a convergent plate boundary at 100 km depth is different from elsewhere. Briefly explain why using the information provided in the figures here. Do not copy from the internet.
10) The lava that erupts in the rift valleys and volcanoes along divergent plate boundaries is generally mafic in composition and not felsic or intermediate in composition. Why? Use the information in sections 4.7 and 4.6 along with the observation made by answering question #4 above to formulate an answer.
11) The lava that erupts from the volcanoes that form at convergent plate boundaries can be any composition but averages out to intermediate to felsic in composition. Why? Use the information in sections 4.7 and 4.6 along with the observation made by answering question #8 above to formulate an answer.
12) Summarize the answers to 10 and 11 to explain why the oceanic crust is mafic and why the continental crust is intermediate to felsic in composition. No need to look this up—use what you wrote for answers to 10 and 11 combined with information from the figures above if needed to explain this. If you need help with this, ask your team mates within the discussion. I will also be checking in to assist.
