MARS 2310 Assignment 2
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University of Texas, Rio Grande Valley *
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1403
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Geology
Date
Feb 20, 2024
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3
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Marine Ecosystem Dynamics
Lesson 2 Assignment: Plate Tectonics and Marine Sediments (100 pts)
1.
Identify all of the different observations Alfred Wegener used to support his theory
of continental drift.
The observations Alfred Wegner used to support his theory of continental drift included
extensive studies done on plant and animal fossils from various continents/coasts that proved to
be a match to each other. Other observations that further supported his theory were observing the
patterns of glaciation on the plains of Africa. This observation implied how the continents were
once located in different climate zones. There were many other observations conducted by
Wegner all proving that the continents once fit together like a jigsaw puzzle forming a
supercontinent (pangea).
2.
Identify all of the different observations used to support Harry Hess' theory of
seafloor spreading.
Harry Hess’ theory of seafloor spreading was supported by his observations of the
alignment of mountain ranges (mid-ocean ridges) in the center of ocean basins. This observation
suggested the formation of new oceanic crust that was getting pushed away and thus causing the
sea floor to spread. Other observations included
3.
What is the mechanism by which lithospheric plates move?
The mechanism that causes lithospheric plates to move is presumed to be a combination
of convection in the mantle and slab pull that is caused by the subducting lithosphere.
4.
What is a subduction zone?
A subduction zone refers to the process of two tectonic plates colliding and one of the
plates gliding beneath the other plate. Subduction zones are typically where some of the most
intense earthquakes and volcanoes arise.
5.
How are magnetic stripes on the seafloor created?
Magnetic stripes are created through spreading centers which refers to the process of two
oceanic plates moving apart from each other. As the process of seafloor spreading is taking place
magma rises to the surface and essentially creates new bands of ocean floor. What follows next is
the earth’s magnetic field flipping causing the next stripe of ocean floor to align with its polarity
in the opposite direction.
6.
What are the 3 types of plate boundaries?
The three types of plate boundaries are; divergent, convergent, and transform.
7.
What is seafloor spreading?
Seafloor spreading is the geological phenomenon of tectonic plates essentially splitting
apart from each other. This process creates new oceanic crust through volcanic activity that
occurs at mid-ocean ridges.
8.
Explain the theory of plate tectonics.
Wegner’s theory of plate tectonics claims that Earth’s lithosphere (crust and upper
mantle) is separated into these large rocky plates that move across Earth. The theory also claims
that because of these plates and the shifting/movement that occurs, there is natural phenomena
such as mountains, volcanoes, and tsunamis.
9.
Describe the 3 types of plate boundaries including their geological features.
Divergent boundaries occur when two tectonic plates are moving away from each other.
Magma from the mantle rises up to fill the gap that is being created by the divergence of the
plates. Magma cools and solidifies to form new crust and create mid-ocean ridges or rift valleys.
Convergent boundaries happen when two plates are moving towards each other. These plates
eventually collide and form mountains. Oceanic crusts colliding result in subduction zones in
which a deep ocean trench can be formed. Transform boundaries occur when two plates are
sliding past each other in a horizontally form. Frequent earthquakes usually follow this form of
plate boundaries.
10. Describe the Wilson Cycle.
The Wilson Cycle is a concept used to demonstrate the opening and closing of ocean
basins. The initial stages of the Wilson cycle are characterized by the opening of an ocean basin
resulting in the formation of a divergent boundary. This expansion proceeds and new oceanic
crust is formed along the boundary. Eventually, the subduction of one tectonic plate beneath the
other occurs, closing the ocean basin. Finally, the collision between the two plates leads the
closure of the ocean basin.
11. Describe how volcanic islands are formed and what can we learn from them in
terms of plate tectonics?
Volcanic islands are the result of magma rising from deep within Earth to eventually form
new crust in the lithosphere. The formation of volcanic islands can tell us in which direction
tectonic plates move and how they interact with each other. An example of this is the formation
of the Hawaiian Islands. They derived from a hot spot and have created a chain of volcanic
islands that demonstrate how those plates were moving.
12. Describe the 3 coral reef stages and how they relate to plate tectonics.
Fringing reefs are formed close to the shore/coastlines. They are the most common type
of reef as they are the initial stages of coral reef. Barrier reefs are commonly found further away
from coastlines and in sinking seafloor areas where they are able to grow upward. Finally, atolls
are found in areas where the seafloor is rapidly sinking allowing them to grow upwards. The
constant movement and changes of plate tectonics can heavily influence the growth and success
of coral reefs.
13. What is lithogenous sediment?
Lithogenous sediments primarily originate from land rocks. They are tiny fragments that
derive from land rocks that end up in the ocean.
14. List the various processes that deposit lithogenous sediment on the ocean floor.
Some of the processes that deposit lithogenous sediment on the ocean floor are water
transports (streams, rivers, rain, and water flows), wind, glaciers, and other anthropogenic
activities. Most lithogenous sediment deposits derive from water transportation in the form of
runoff from rivers and streams that eventually deposit into the ocean.
15. What are biogenic oozes?
Biogenic oozes are a type of sediments that are largely composed of microscopic remains
of microscopic marine organisms. The sediment is composed of at oleast 30% biogenous
material. The two types of biogenic oozes are calcareous and siliceous. Types of siliceous ooze
include diatom, radiolarian, and dinofllagellate ooze. Typeds of calcareous ooze includes
foraminiferan and cocolith ooze.
16. What are relict sediments?
Relic sediments ar coarse particle deposits that are thought to be left by lower sea level.
Theses sediments can be helpful in determining the geological history in which they are located.
17. How are silica oozes generated? What processes control their accumulation on the
seafloor?
Siliceous ooze is largely composed of the hard remains of silica-containging organisms.
These organisms are primariyly diatoms, radiolarian, and dinoflagellates. These organism control
the accumulation of silica ooze on the seafloor through processes such as photosynthesis.
18. How are calcareous oozes generated? What processes control their accumulation on
the seafloor?
Calcareous oozes are composed of the hard remains of organisms containing calcium
carbonate. Calcerous secreting organisms include coccolithophorids and foraminifernans.
19. What is a hydrogenous sediment? Give at least 4 examples.
Hydrogenous sediment (also known as authigenic sediment) is a type of sediment that is
formed directly by precipitation from seawater. Examples of a hydrogenous sediment include:
manganese nodules, phosphorite nodules, oolite sands, and evaporites.
20. What are cosmogenous sediments?
Cosmogenous sediments are ocean sediments that have extraterrestrial origins. These
sediments typically derive from dust/debris from space. The dust comes from either a comet,
metoey, or asteroid’s debris.
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