Lab Report, MetamorphicRocks!

PRE-LAB QUESTIONS 1. Where might you find regional metamorphic rocks being formed today? (Select all that apply.) A . In the core of the Himalayas B. Adjacent to a lava flow C. Near a deep, large igneous intrusion D. In a shallow fault zone E. None of the above A and C. 2. Match the following foliated rocks with their metamorphic grade: A. Schist 1 . Highest grade B. Slate 2 . Second-highest grade C. Gneiss 3 . Second-lowest grade D . Phyllite 4. Lowest grade Schist is second highest grade/ Slate is the lowest grade. Gneiss is the highest grade. Phyllite is the second lowest grade. 3. The parent material of a metamorphic rock is known as the ___ Protolith ____. 4. True or False? Regional metamorphism is a localized event. False 5. What are the three types of metamorphism? v. SU22

Regional, Thermal (contact) , and Dynamic DATA SHEET Table 3. Metamorphic Rock Identification Rock Sample Foliated (Yes/No) Grain Size Other Textural Features Composition Rock Name Protolith M yes Medium to coarse Altering light and dark layers can scratch glass, reflective. Amphibole, biotite, muscovite Gneiss Shale, mudstone, or granite N no Fine to coarse Reacts to acid, crystalline texture, equal sized grains, soft Calcite Marble Limestone or dolostone O yes fine Smooth and dull, can scratch glass Biotite, muscovite Slate Shale or mudstone P Yes Fine Wavy foliation, very small crystals Chlorite, quartz, muscovite Phyllite Shale or mudstone Q No Fine to coarse Sandy texture, can scratch glass, reflective. Quartz Quartzite Quartz-rich sandstone R No Fine Black and glossy, conchoidal fracture Carbon Anthracite Bituminous coal 1. How did you determine the compositions of sample N and sample Q? For sample N I was able to determine the composition because it had a reaction with acid and was soft meaning it had to be limestone. For sample Q it had a sandy texture, could scratch glass and I no reaction leading it to be quartz-rich sandstone. 2. Where might you find a rock like sample M being formed on Earth today? v. SU22

6. What is contact metamorphism? Contact metamorphism is caused by heat conducted into country rock from an igneous intrusion. Hydrothermal fluid circulates through both intrusion and wall rock. The wall rock will undergo metamorphism created highest grade rocks adjacent to pluton. 7. Name at least two (geographic) areas of the United States have experienced regional metamorphism. The Appalachian Mountains and The Acadian Orogeny 8. Where on Earth do we often find examples of metamorphism due to chemically active fluids? Takes place in continental collisions or subduction. 9. What two properties of rock change during metamorphism? Mineralogy and texture. 10. What two things can happen to minerals during metamorphism? Growth of new minerals and chemical reaction digest minerals of protolith. 11. Other than old blackboards, what can slate be used for today? Used as roofing material. 12. What metamorphic rock is created from sandstone? Quartzite 13. How would you tell the difference between quartzite and marble if you did not have acid available for testing? v. SU22

Marble is soft and quartzite is hard and can scratch glass. 14. Is contact metamorphism likely to produce foliated rocks? Explain why or why not. It is not likely because it takes place without application of differential compression of shear, commonly producing hornfels, a nonfoliated rock. 15. Metamorphic rocks can be classified as low grade, intermediate grade, or high grade, based on the temperature and pressure conditions under which they form (in addition to the figure in 6.4 of the textbook, refer to supplemental images in Canvas if needed). At what grade (low, intermediate, or high) would you classify schist? Slate? Gneiss? What do large crystals generally indicate in terms of the metamorphic grade? Schist is intermediate grade. Slate is low grade and gneiss is high grade. Large crystals can indicate the temperature of heat the rock was produced at. Slate has small crystals because it was created is lower heat than schist and gneiss. In schists the temperature is hot enough that individual crystals are big enough to be visible. Gneiss has little to no mica due to forming at such high temperatures that mica is stable. 16. The temperatures and pressures needed to create a particular metamorphic rock can also tell us about the tectonic environment in which it formed. Consulting the diagrams referred to in the above question, your textbook, the videos, or other sources as necessary, in what tectonic environment do serpentinite and soapstone form? What about gneiss? hornfels? Serpentinite and soapstone are formed by hydrothermal metamorphism forming along mid- ocean ridges. Gneiss forms by regional metamorphism at convergent plate boundaries. Hornfels are by contact metamorphism and can be found underground volcanic settings, like hotspots, divergent plate boundary, or subduction zones. III. Reflection: v. SU22