Earth Systems 3209

1. Earth Systems 3209 Reference: Chapters 4, 15, 16, 19; Appendix A & B Unit: 4The Forces Within Earth

2. Unit 4: Topic 5.3 Intraplate Volcanism and Hotspots Focus on . . . • defining hotspot. • identifying two tectonic environments associated with hotspots and provide and example of each.

3. Plate Boundary Volcanism • Volcanoes are associated with two of the three types of plate boundaries, these being convergent and divergent boundaries.Very littlevolcanic activity is seen at transform fault boundaries. • Volcanism associated with plate tectonic activity are found in three areas on Earth: • Ridges (or spreading centers) • Subduction zones • Interior of tectonic plates Text Reference: Pages 543 – 544 & 121 – 122

4. Intraplate Volcanism • This type of volcanism is produced by rising hot mantle material called Hot Spots. • Hot spots can be found under continents and the ocean floor. • Intraplate volcanism occurs in two areas: • Beneath the oceans (Hawaiian Islands)Produces basaltic magma sources in oceanic crust. • Within continental plates (Yellowstone National Park)Produces granitic magma sources in continental crust.

5. Magma Intraplate Volcanism • Beneath Oceans • Hotspots within the mantle cause magma to move upward and flow onto the ocean floor forming shield volcanoes and volcanic islands. • An example includes the Hawaiian Islands.

6. Intraplate Volcanism • 2) Within Continents • Hotspots within the mantle cause magma to move upward and flow onto the continental surface forming volcanoes and lava plateaus. • Yellowstone National Park has this type of volcanism.

7. Volcanism on a tectonic plate moving over a hot spot • Associated with plumes of heat in the mantle. • Form localized volcanic regions in the overriding plate called a hot spot.

8. Example 1: Using Plate Tectonics, explain why the Hawaiian Islandsvary in age and amount of volcanic activity. Answer: The Hawaiian Island chain formed as a result of the Pacific plate moving over a hot spot located in the mantle beneath the pacific ocean. The oldest volcanic islands are located the farthest from the hot spot and has little to no volcanic activity. Whereas the closer you get to the hot spot, the younger the volcanic islands are and the greater the amount of volcanic activity. For example, the island of Hawaii is presently positioned directly above the hot spot and experiences volcanic activity on a regular basis.

9. Example 2: The Hawaiian islands are located where the Pacific plate is doing which of the following? (A) being thrust over the North American Plate (B) diving under the North American Plate (C) migrating over a hot spot (D) separating from the North American Plate Which type of volcanic eruption resulted in the formation of the Hawaii islands? (A) Hawaiian eruption (C) rift eruption (B) hot spot eruption (D) subduction eruption

10. Your Turn . . . Take the time and complete the following questions . . .(Solutions to follow) Question: With the aid of a labelled diagram explain how the Hawaiian Island Chain formed.

11. Solutions . . . Question: With the aid of a labelled diagram explain how the Hawaiian Island Chain formed. Answer: The Pacific plate moved over a stationary hot spot, forming new volcanic islands directly over the hot spot. The older volcanic islands move with the Pacific plate and travel farther away form the hotspot with each passing year. Over a period of time a chain of islands form. The older islands are no longer fed by the hot spot and therefore become dormant (extinct) or inactive volcanic islands.

12. Summary . . . Overview of Points covered: • Hot Spot • Is a concentration of heat in the mantle, capable of producing magma that extrudes onto the surface. • Two tectonic environments are associated with hotspots: • Beneath the oceans (Hawaiian Islands)Produces basaltic magma sources in oceanic crust. • Within continental plates (Yellowstone National Park)Produces granitic magma sources in continental crust.