E1_NP_PlateTectonics_rv0 2
pdf
keyboard_arrow_up
School
Northern Kentucky University *
*We aren’t endorsed by this school
Course
130
Subject
Geology
Date
Apr 3, 2024
Type
Pages
4
Uploaded by DukeFinch1072
Geology Name: Exercise: Plate Tectonics First, read Lab 2, then answer the following questions. Activity at plate boundaries The following diagram shows the locations, types, and names of major plate boundaries (divisions in the lithosphere) across the planet. (25 pts total, each question 1 pt unless noted otherwise) Some of the evidence that has led to our understanding of plate tectonics has come in the form of the location of earthquakes and volcanoes. This map shows major earthquakes between the years 1960 and 2000. 1. How does this distribution compare with the location of plate boundaries? 2. What does this mean is happening at plate boundaries? The map to the right shows volcanoes that have erupted in the last 10,000 years. 3.
How does this distribution compare to the location of plate boundaries? 4.
What does this mean is happening at plate boundaries?
2 Types of plate boundaries So we know there is activity at these plate boundaries. Let’s look at this activity in a little more detail by examining exactly what is going on at each boundary. Look again at the first map on the preceding page (shows plate boundaries). The arrows on the diagram indicate the direction the lithosphere is moving at each of the major plate boundaries. There are three directions: plates move away from each other (
Å→
divergent), toward each other (
→Å
convergent), or slide past one another (transform ÇÈ
). Le
t’s consider both divergent and convergent plate boundaries in turn. Divergent Plate Boundaries At these plate boundaries, plates move apart. When this occurs within oceanic crust, it is known as sea floor spreading
. When it occurs within continental crust, it is known as continental rifting
. We are going to focus on sea floor spreading for now. The following diagram shows the profile of the Atlantic Ocean sea floor. The most obvious feature is the large ridge that runs down the center of the Atlantic Ocean basin. This is the Mid-Atlantic Ridge. There is volcanic activity all along this ridge, where new oceanic crust is formed. 5.
How does the shape of the Mid-Atlantic Ridge compare with the shapes of the continents on either side of the Atlantic Ocean? Geologists are able to determine the age of rocks on the sea floor. The map displayed on the screen in the front of the room shows the age of the oceanic crust around the Mid-
Atlantic Ridge. (see your text, Ch 2, or lecture slides) 6.
With respect to the Mid Ocean Ridge, what areas have the oldest sea floor? How old is the oldest sea floor? 7.
With respect to the Mid Ocean Ridge, what areas have the youngest sea floor? How old is the youngest sea floor (think about it for a second)? 8.
Describe as best as you can what is going on at mid-ocean ridges. Remember the direction of plate movement. (3 pts)
3 9.
Does this provide a mechanism for Wegener’s Continental Drift? How does the relationship of the continents of North America, South America, Africa, and Europe to the Mid-Atlantic Ridge support the existence of Pangea? (3 pts) Convergent Plate Boundaries Divergent plate boundaries in oceanic crust coincide with large ridges. Convergent plate boundaries in oceanic crust, on the other hand, coincide with very deep trenches. One runs along the west coast of South America. Observe on the map on the first that plates do indeed move toward each other here: the South American Plate is converging with the Nazca Plate. 10.
What feature(s) can be found running down the western side of South America? (Hint: the map of the first page may help.) (2 pts) The map and graph below show the location and depth of earthquakes at this plate boundary. The first you should observe is the distribution of earthquakes as you look deeper under the surface. 11.
Taking into account the direction of plate movement, what do you think is going on here? (2 pts) 12.
How might this explain the presence of the feature(s) you observed in question 10? (2 pts)
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
4 Hotspots: Calculation of Pacific Plate Migration Rate from
Hotspot Data The Hawaiian-Emperor seamount chain stretches for 6,000km across the Pacific Ocean. This string of more than 100 volcanoes was formed as the Pacific plate slid across a hot spot (or mantle plume) in the asthenosphere below. Some of these volcanoes extend above sea level to form islands while others are submerged seamounts. Over time the volcanoes erode, cool and subside below sea level often forming flat-topped guyots. 13. Calculate the rate (distance/time) in cms/year at which the Pacific plate is sliding across the hot. Show all calculations!
(Hint: 1 km=1000 m; 1 m=100 cm) (4 pts) Rate = distance / time Distance: Kauai to Kilauea = 519 km Age of Kauai Volcanic Rocks = 5.1 Ma Age of Kilauea Volcanic Rocks = 0.2 Ma How does the plate movement rate vary if we calculate between Midway and Kilauea? Distance: Midway to Kilauea = 2432 km Age of Midway Volcanic Rocks = 27.7 Ma Age of Kilauea Volcanic Rocks = 0.2 Ma Rate = distance / time 1000 m 100 cm 519 km x ---------- x ---------- = 51,900,000 cm’s
1 km 1 m 5.1 million years - 0.2 million years 4.9 million yrs. = 4,900,000 yrs. 51,900,000 cm’s
--------------------- = 10.59 cm’s/yr
. 4,900,000 yrs.