Note:
this image is flipped from the image in the document you
downloaded. That is DELIBERATE, to encourage you
to learn the processes and characteristics of an
Ocean-Ocean Convergent Boundary. You will draw
your own as a mirror image of this one. As you
draw it, carefully observe the characteristics in this
kind of boundary. Try drawing the same features as you saw in the Continent-Ocean Convergent Boundary here, with the Oceanic plate on the right being subducted under the left. |
|
As you
can see, the same things happen with an Ocean-Ocean
Convergent Boundary as happens with a Continent-Ocean
Boundary. When two Oceanic plates converge, you
still have: 1. Subduction Zone 2. Accretionary Prism/Wedge (it is drawn small here, but it can be very large. Some of the Caribbean Islands are Accretionary Wedge sediments piled above sea level.) 3. Deep Ocean Trench (world's deepest ocean anywhere is the Marianas Trench at 11 km, an Ocean-Ocean Convergent Boundary) 4. Benioff Zone (Earthquakes) 5. Magma Chamber The only significant difference is that volcanoes that rise from the Magma Chamber start on the sea floor rather than on a continent. When the volcanoes reach the surface, they make a series of volcanic islands known as a Volcanic Island Arc. |
|
For comparison, here's the Continent-Ocean
Convergent Boundary. Notice how many features
are common between the Continent-Ocean and the
Ocean-Ocean convergent boundaries. One question to think about: Since we have 2 Oceanic plates colliding, what will determine which one undergoes Subduction? Think back to the Divergent Boundary. Why is the Mid-Ocean Ridge elevated, and why does it subside away from the center? Temperature. The temperature at the ridge is higher, and the plate cools off as the plate moves away from the Divergent Boundary. This means that the Oceanic Crust is colder, and denser, as it ages. So if 2 Oceanic plates collide, the one that gets subducted will be the colder, denser, older plate. Where would you find features like this? Anywhere that you find a usually arc-shaped chain of generally active volcanic islands, with a trench on one side, and lots of earthquakes, that is evidence that you are at an ocean-ocean convergent boundary. Look at a map of earthquake locations and a phyisiographic map that shows volcanic island arcs and trenches and see if you can figure out where to find that kind of tectonic boundary. Now click your "back" button to go back to the Plate Tectonics page. |