Metamorphic Rocks Questions
- Compare and contrast the two main types of metamorphism.
- Describe how to recognize the two main texture groups of metamorphic rocks.
- Describe the three changes to rock that occur during metamorphism.
- Explain how "high grade" and "low grade" metamorphic rocks differ.
- Explain how an "index" mineral can be useful.
- Explain how the parent rock affects a resulting metamorphic rock.
- Explain what agents (forces) cause metamorphism.
- List metamorphic rock types based on the presence or absence of foliation.
- The common mineral biotite mica is an index mineral. With higher temperatures and pressures another index mineral, the semi-precious gem garnet appears. Imagine you are hiking on a mountain one afternoon:
- The first rock you see is the sedimentary rock, shale.
- As you walk you notice the rock has become rather shiny and you see flecks of biotite mica in the rock. The shale here was metamorphosed.
- After a several kilometers you notice the rock now has a grainy appearance and you start seeing garnets in the rock.
- Distracted by the beautiful mountain scenery you forget to notice the rock for the next km or two.
- When you think about the rocks again you see that you are now climbing on granite.
In terms of agents of metamorphism, types of metamorphism and index minerals, describe what you have seen. Hint: draw a picture or diagram of the bedrock seen during your walk.
- Breccia is a name for rock composed of sharp fragments in a matrix of (or surrounded by) finely ground rock. Explain why that would make sense for the metamorphic rock found at a fault.
- From the graph, provide the range of temperatures and pressures that can be found in subduction zones of convergent plate boundaries?
- From the graph, provide the range of temperatures and pressures that can be found in zones of igneous intrusion at convergent plate boundaries?