308 W21 Rock Cycle Lab 6 -1
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Geology 308 Lab Week 6
The Rock Cycle Optional: A Rock Cycle Primer
To ensure that you grasp the basic principles of the rock cycle, go to the following website, read the material, and complete the online test:
https://www.learner.org/series/interactive-rock-cycle/
If you have taken a geology course in the past (high school or 100-level introductory course) then this test will likely be a review for you. If you are unfamiliar with the rock cycle, use the other links along the top of the website (“Types Of Rocks,” “How Rocks Change,” “The Rock Cycle Diagram”) to help.
Below is a schematic diagram or flow chart
showing various possible pathways that
rock in various forms can take in passing through different circumstances within or on the surface of the earth:
Your job in this lab is to trace the paths of rocks in the course of their transformations, as they take a number of different routes through the rock cycle. In
following a rock through its various incarnations you will use the terminology and concepts below.
Components of the Rock Cycle
The list is not meant to imply that the rock types are formed in a certain order. This is just a list of the kinds of rocks you may encounter, and their origins. Sediment = loose particles of any kind or size
Sedimentary rock - a rock made from sediment
Magma = liquid rock, becomes lava or tephra upon eruption (effusive or explosive)
Igneous rock (intrusive or extrusive) – rock made from magma
Metamorphic rock – made from any other kind of rock, through application of HEAT AND/OR PRESSURE, usually under conditions of burial deep in the earth under other rock
Events of the Rock Cycle
The list is not meant to imply that these events happen in a certain order. They are simply common occurrences in the endless recycling of solid matter on the planet Bedrock is exposed, by uplift and erosion Sediment is formed, by weathering and erosion
Sedimentary rock forms, by burial, compaction, and cementation: = lithification Metamorphic rock forms, due to application of heat and/or pressure to other rocks Magma is created, due to melting of rock
Igneous rock forms (intrusive or extrusive), due to cooling and solidification of magma
Processes that power the Rock Cycle
Different rock types form under different conditions, through different processes.
Weathering (physical, biological and/or chemical) Erosion, transport and deposition of sediments Shallow burial and lithification
- compaction and cementation of rock or sedimentary fragments into rock Deep burial and heating
Melting Cooling and crystallization Uplift , which leads to exposure of bedrock
Volcanism
INSTRUCTIONS
In Part 1 below, just
list the processes, events, and components
necessary to get from one stage in the Rock Cycle to the next.
In Part 2 below, I would normally have you
draw flow chart diagrams
like that above for each of the following questions, showing a plausible pathway through the Cycle. Instead, just list necessary processes, events, and components, as in Part 1.
Part 1: Applying Your Knowledge of the Rock Cycle
Some of these pathways will be long, some will be short. Whatever it takes. 1. What is a potential pathway in the rock cycle for an exposed metamorphic rock
at the Earth’s surface to turn into an exposed intrusive igneous rock
(such as a stitching pluton)? Your answer should be an ordered list
of appropriate parts of the rock cycle, including ALL the necessary processes and products. Use any and all relevant terms from the lists provided above.
1. Weathering and Erosion: The exposed metamorphic rock undergoes physical, biological, and/or chemical weathering, followed by erosion.
2. Transport and Deposition: The particles and sediments from the weathered metamorphic rock are then transported and eventually deposited.
3. Sediment Formation: The deposited materials accumulate and form sediment.
4. Burial, Compaction, and Cementation (Lithification): Over time, the sediment gets buried under additional layers and undergoes compaction and cementation, turning into sedimentary rock.
5. Deep Burial and Heating: The sedimentary rock is then subjected to deep burial where it experiences increased temperatures and pressures.
6. Formation of Metamorphic Rock (Again): The increased heat and pressure transform the sedimentary rock back into a new form of metamorphic rock.
7. Melting: As the metamorphic rock is buried deeper or subjected to additional heat it begins to melt, forming magma.
8. Cooling and Crystallization: The magma then cools slowly and crystallizes beneath the Earth's surface, forming an intrusive igneous rock.
9. Uplift and Exposure: Tectonic forces eventually uplift the area, bringing the intrusive igneous rock closer to the surface.
10. Erosion: The overlying material is eroded away, exposing the igneous rock at the Earth's surface.
2. What is a potential pathway in the rock cycle for a basaltic lava flow rock
to turn into an exposed metamorphic rock
? Your answer should be an ordered list
of appropriate parts of the rock cycle, including ALL the necessary processes and products. Use any relevant terms from the lists provided.
1. Cooling and Solidification: After the basaltic lava is erupted, it cools and solidifies to form
a basaltic rock.
2. Weathering and Erosion: Over time, the basaltic rock is subjected to weathering and erosion due to physical, biological, and/or chemical processes.
3. Transport and Deposition: The eroded particles are transported by natural agents like water, wind, or ice, and are eventually deposited.
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4. Sediment Formation: These particles accumulate and form sediments.
5. Burial, Compaction, and Cementation (Lithification): The sediments undergo burial under additional layers of sediment. Over time, they become compacted and cemented, forming sedimentary rock.
6. Deep Burial and Heating: As more layers deposit over the sedimentary rock, it gets buried deeper into the Earth's crust, where there will be increased temperature and pressure.
7. Metamorphism: The combination of high temperature and pressure changes the mineralogy and texture of the sedimentary rock, transforming it into a metamorphic rock.
8. Uplift: Tectonic forces uplift the metamorphic rock towards the Earth's surface.
9. Exposure: Erosion and weathering processes remove the overlying material, eventually exposing the metamorphic rock at the Earth's surface.
3. What is a potential pathway in the rock cycle for a sedimentary rock
exposed high in a mountain range to become an exposed metamorphic rock
? Your answer should be an ordered list
of appropriate parts of the rock cycle, including ALL the necessary
processes and products. Use the relevant terms from the lists provided above.
1. Weathering and Erosion: The sedimentary rock at high elevations is subjected to weathering due to temperature, precipitation, and wind.
2. Transport and Deposition: The weathered material may be transported down the mountain through processes like landslides, mudflows, or river transport and then deposited.
3. Burial and Lithification: Over time, if more sediments are deposited on top, the sedimentary rock can be buried again, leading to further lithification.
4. Deep Burial and Heating: As tectonic forces build the mountain, the rock is buried deeper, subjected to higher temperatures and pressures.
5. Metamorphism: The high temperatures and pressures cause changes in mineral composition and texture, turning the sedimentary rock into metamorphic rock.
6. Uplift: Tectonic forces continue to uplift the mountain range, bringing the metamorphic rock closer to the surface.
7. Exposure: Weathering, erosion, and removal of the overlying rock layers expose the metamorphic rock at high elevations in the mountain range.
4. What is the simplest path to convert unconsolidated underwater sedimentary deposits
into a sandstone mountain range
? This is not a trick question, it really is simple and the list
of processes is blessedly short. But keep this in mind when dealing with the same sediments as part of an accreting terrane later; that will be a great deal more complicated.
1. Lithification: The loose sedimentary deposits first undergo compaction from the weight of overlying materials and then cementation, where minerals come from groundwater and bind the sediment grains together, forming sandstone.
2. Uplift: The lithified sandstone is then subjected to tectonic forces that drive the rock upwards, forming a mountain range.
3. Erosion and Exposure: Finally, erosion strips away the overlying sediments and rocks to expose the sandstone as a mountain range.
Part 2: The Rock Cycle and the Coast Range
Sediments forming the Coast Range in Oregon originated from several sources. Your next assignment is to trace the paths through the rock cycle for some of these sources.
FOR EACH QUESTION JUST TURN IN A LIST OF THE PARTS OF THE CYCLE IN ORDER.
5. The Klamath Mountains sources
The earliest (bottom) sediments in the Coast Range came from the Klamath Mountains, a collection of accreted terranes. Some of the Klamath terranes were seamounts and oceanic crust originating from volcanic arcs; others were oceanic sedimentary rocks like limestone and chert. ALL these were metamorphosed and deformed during terrane accretion
, so try to include those events in your efforts.
A. Using the terminology of the Rock Cycle above, trace a plausible pathway for offshore volcanic arc rocks
(an oceanic island arc) to become Coast Range sedimentary rocks
exposed at the surface today, including accretionary burial
and metamorphism
, and don’t forget uplift and erosion, which might occur several times in your pathway
. To help visualize this I recommend you and your teammates draw a flow chart
with the relevant parts of the rock cycle including ALL relevant processes and products, and compare notes.
1. Volcanic Eruption: Eruption of volcanic material forms an oceanic island arc.
2. Cooling and Solidification: The volcanic material cools and solidifies to become igneous rock.
3. Weathering and Erosion: The igneous rock is weathered and eroded.
4. Sediment Formation: The eroded material becomes unconsolidated sediment.
5. Transport and Deposition in Ocean: The sediment is transported by water and deposited in an oceanic environment.
6. Burial and Lithification: The sediment is buried and undergoes lithification to become sedimentary rock.
7. Accretion and Burial: Tectonic forces cause the sedimentary rock to be accreted to a larger landmass and further buried.
8. Metamorphism: The buried rock is subjected to high pressure and temperature, leading to metamorphism.
9. Uplift: Tectonic uplift brings the metamorphosed rock towards the surface.
B. Using the terminology of the Rock Cycle, trace a plausible pathway for oceanic sediments
to become Coast Range sedimentary rocks
exposed today, including that accretionary burial
and metamorphism
, and don’t forget possible different episodes of uplift and erosion
. To help visualize this I recommend you and your teammates draw a flow chart
with the relevant parts of the rock cycle including ALL relevant processes and products, and then compare notes. 1. Sediment Formation: Accumulation of oceanic sediments through the erosion of land and
volcanic material.
2. Transport and Deposition: Transportation of these sediments to the ocean floor and deposition in deep marine environments.
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3. Burial: Continued sedimentation leads to the burial of older sediments under newer layers.
4. Lithification: Over time, the buried sediments undergo lithification, turning into sedimentary rock.
5. Accretion: The sedimentary rocks are accreted to a continental margin because of tectonic plate movement.
6. Metamorphism: The accreted sedimentary rocks are subjected to metamorphism due to increased pressure and temperature.
7. Uplift: Tectonic forces cause the uplift of the metamorphosed sedimentary rocks.
8. Erosion: Erosion strips away the overlying material, exposing the older rocks.
9. More Uplift: Further tectonic activity can lead to additional uplift of the rocks.
10. Formation of the Coast Range: The uplifted and eroded rocks now form part of the Coast Range, exposed at the surface.
6. The Idaho Batholith sources
The Tyee Formation of the Oregon Coast Range was created during the Eocene primarily by
rivers carrying sediment from the Idaho Batholith through the isolated and separated individual volcanoes of the earliest Western Cascades Mountains to the edge of the continent, and depositing this sediment in a forearc basin.
Using the terminology of the Rock Cycle, trace a plausible pathway for subduction zone magma
to become the Idaho Batholith and then eventually to reappear as Coast Range sedimentary rocks
exposed today. To help visualize this I recommend you and your teammates draw a flow chart
with the relevant parts of the rock cycle including ALL relevant processes and products. And compare notes.
1. Subduction: Oceanic crust is subducted beneath continental crust, leading to the melting of mantle material above.
2. Magma Formation: This melting creates magma.
3. Intrusion: The magma intrudes into the overlying continental crust, where it slowly cools
and crystallizes to form the Idaho Batholith, which is an intrusive igneous body.
4. Uplift: Tectonic activity uplifts the region containing the batholith.
5. Erosion: Erosion begins to break down the exposed batholith, creating sediments.
6. Transport: Rivers carry these sediments from the eroding Idaho Batholith.
7. Deposition: The sediments are deposited in a forearc basin, which is part of the developing Coast Range.
8. Lithification: Over time, these sediments become compacted and cemented to form sedimentary rocks.
9. More Uplift and Erosion: Additional uplift and erosion expose these sedimentary rocks within the Coast Range.
7. The Cascade Volcano sources
When the Western Cascade Volcanoes grew old enough and large enough to form a continuous volcanic arc mountain range and block through-flowing rivers, they themselves became sources for sediments filling the same forearc basin. Using the terminology of the Rock Cycle, trace a plausible pathway for subduction zone magma
to become first the Cascade Volcanoes and then Coast Range sedimentary rocks
exposed today. Again, you might draw a flow chart
with the relevant parts of the rock cycle.
1. Subduction: An oceanic plate subducts beneath a continental plate, creating a subduction
zone.
2. Magma Formation: The subduction process creates magma due to the melting of the mantle and subducted material.
3. Volcanic Eruption: The magma rises through the crust and erupts to form the Cascade Volcanoes.
4. Cooling and Solidification: The volcanic material cools and solidifies to form volcanic rock.
5. Weathering and Erosion: The volcanic rock is weathered and eroded over time.
6. Sediment Formation: The eroded volcanic material forms sediment.
7. Transport: The sediments are transported by rivers and streams.
8. Deposition: The sediments are deposited in the forearc basin adjacent to the volcanic arc.
9. Burial and Lithification: The deposited sediments are buried, compacted, and cemented over time to form sedimentary rocks.
10. Uplift: Tectonic activity uplifts the sedimentary rocks.
11. Exposure: Continued erosion eventually exposes the sedimentary rocks that are now part of the Coast Range.
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