Learning Exercise 3
docx
keyboard_arrow_up
School
East Carolina University *
*We aren’t endorsed by this school
Course
1500
Subject
Geology
Date
Apr 3, 2024
Type
docx
Pages
4
Uploaded by ChancellorSpider4026
Dynamic Earth GEOL-1500
Spring 2024
Metamorphic Rock Description and Classification
Learning Exercise
Name: Haley Young Learning Goals:
To know the definition of a metamorphic rock
To understand the concept of protoliths
To know how metamorphic rocks are classified.
Understand the processes that occur during metamorphism
To understand the relationship between tectonic environment and metamorphism
Questions:
Part 1: Metamorphic processes
1. What is a metamorphic rock?
A metamorphic rock is a rock that changed from its original form due to high heat, high pressure,
or a combination of the two. 2. What physical changes occur to the mineral content and grain structure when a rock undergoes
metamorphism?
Metamorphism alters the rocks texture, layering crystals, and banded appearance. 3. What are the physical “agents of metamorphism” (e.g. the physical conditions that cause metamorphism)?
The physical agents of metamorphism are heat from the magma chamber, geothermal gradient and pressure from tectonic plate collisions. 1
4. Define “differential stress”. Describe how it may affect the minerals in a protolith during metamorphism.
Differential stress is the difference between the greatest stress experienced by an object. Minerals
that crystalize in differential stress have preferred orientation. 5. What are two main subdivisions of metamorphic rocks? List at least two
rocks in each subdivision:
Foliates : slate, schist
Non Foliates: marble, hornfel
6. Name a metamorphic rock that forms primarily through the process of recrystallization. What is mineral that is recrystallized?
Quartzite is a rock that forms primarily through the process of recrystallization.
Part 2: Metamorphic environments
7. Geologic and tectonic setting influences the type
of metamorphism that may occur. What type
of metamorphism is primarily caused by increased heat
from a nearby igneous body? 2
Contact Metamorphism occurs when rocks are nearby and is increased in heat. 8. What type of metamorphism occurs near mid-ocean ridges? What is the protolith
and the resulting metamorphic rock type in this setting? Which metamorphic agents
were involved?
Hydrothermal Metamorphism occurs near mid ocean ridges, rocks like clay, talc and chlorite are formed, heat pressure and chemical fluids are the agents involved. 9. What are the pressure and temperature conditions in a subduction zone at an ocean-
continent convergent plate boundary? What metamorphic rocks/facies may be created under those conditions?
Subduction zone consists of material scraped of the ocean floor near the coast and rocks like basalt are formed. 10. Consider the following situation: The protolith is a shale. The rock is exposed to intermediate grade metamorphism and now exhibits a strong foliation. Name three minerals that may form from neocrystallization in this rock.
Mineraks that may form would be quartz, mica, and large garnets 11.
Consider the following situation: The protolith is a mafic igneous rock. The rock is exposed to amphibolite facies
metamorphism. Name a geologic setting in which this is likely to occur. In addition, list two neocrystallized minerals that may form in this rock.
A geologic setting this would likely occur would be in the mountains. Minerals would be epidote, garnet, and aimandine 12.
Given the following pressure and temperature conditions, name the metamorphic facies: 4 kbar, 350ºC. Explain your answer.
13. How deep in the crust is 4 kbar? Lithostatic pressure within the crusts results from the weight of the rocks above. Assume an average density of 2750 kg/m
3
. Use the equation P=ρ*g*h or P/(ρ *g)=h
3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
P=pressure (e.g. kbar), ρ=density, g=gravity 9.8 m/s
2
, h= depth (m), 1 kbar=1,000 bars, 1 bar=100,000 Pa, 1 Pa=kg/(m*s
2
), 1 kbar =100,000,000 Pa, 1 km =1000 m. Give your answer in kilometers.
1,536 km
4