Ochem Lab 12 Answers

Lab 12 (At-Home): Due at 5pm on Friday October 21st

Wilson Cycles

Gregory Baker (Aug 2016)

ANSWER SHEET

LEARNING OBJECTIVES:

1. Understand the concept of a Wilson Cycle
2. Define the stages in a Wilson Cycle
3. Predict Earth’s future using the concepts of Plate Tectonics and Wilson Cycles

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Lab 10 Part A:  What is a Wilson Cycle?

Question A.1:  At first glance, when the tectonic plate containing the continental land mass splits apart, it looks like the two are moving “away” from each other.  However, if one remembers that the Earth is round, you could also say the two tectonic plates are moving “towards” each other.  Explain.

Depending on the size of the tectonic plate it could also mean moving towards each other, in order for this to happen the plate must be the size of the continent. These also depends on the density, the thickness of the plate, and the composition of the plate. When the two plates move apart is because of the divergent movement plate, it creates a continental crust between the two plates and over time the oceanic crust will be subducted into one of the continental plates, meaning that the two plates will touch each other again.

Question A.2:  

At the 0:28 minute mark in Video 01 (when the continental crust of the two plates are as far apart as they will get), where are volcanoes generating new crust?  Explain.

The volcanoes will be located towards the plate that is being subducted because the oceanic crust will react with continental asthenosphere, were the most magmas are, pushing up the magma and create volcanoes on the continental crust.

Question A.3:  Beginning at the 0:29 minute mark in Video 01, something changes.  Briefly describe the process that occurs at the edge of the western tectonic plate, and then again discuss where there are volcanoes generating new crust.  Explain.

The process that is happening is the subduction, where the oceanic crust is being subducted towards the western plate, pushing up the magma that is under the continental crust and that’s where the volcanoes are generated

Lab 10 Part B:  Elements of a Wilson Cycle 

Question B.1  Stable Craton:

A stable Craton is an old part of the continental lithosphere, part of the lithosphere are the crust and the upper mantle, where it has been stable for billions of years

Question B.2  Early Rifting:

An Early Rifting is where the continental crust and the oceanic crust are being pulled apart which is the beginning of divergent boundaries between two tectonic plates and the mid ocean ridge is starting to form.

Question B.3  Full Ocean Basin:

Mainly the two continental tectonic plates are fully apart, spreading apart the lithosphere through a long period of time. Because of these it creates a new ocean floor where it can create ocean ridges, deep sea trenches, linear fracture zones, etc.

Question B.4  Subduction:

Subduction is when the oceanic crust is being subducted under one of the continental plates, making the two continental plates to get closer to each other, and the ocean basins are beginning to get closer too.

Question B.5  Closing Ocean Basin:

Closing ocean basin is where the ocean basin almost closed where the two continental plates are getting closer to each other (collision about to occur), this phase is the beginning of any kind of environmental disaster that could occur like earthquakes

Question B.6  Continental Collision:

Continental collision is when the right continent overrides the left continent, creating a convergent boundary, also the ocean basin is fully closed

Question B.7  Stable Craton: