Subduction Zones are often associated with igneous and metamorphic rock creation:
1. Watch the following animation: http://www.jclahr.com/science/earth_science/animate/
2. Igneous rocks form from molten rock.
3. Metamorphic rocks form from certain areas of the Earth's crust undergo extreme
heat and pressure form most metamorphic
Review of plate tectonics and plate motion
The Earth's outermost layer (the lithosphere) is divided into a number of rigid plates that move
around the Earth's surface. These plates interact with each other at their boundaries. The picture
below shows an outline of the Earth's major plates.
There are three types of plate boundaries: Transverse, divergent and convergent.
When two plates are sliding past each other, they form a transverse boundary. An example of
a transverse plate boundary is the San Andreas Fault between the North American Plate and
the Pacific Plate. Los Angeles is located on the Pacific Plate, which is slowly moving north towards
San Francisco, which is located on the North American plate.
Another type of plate boundary is a divergent boundary or spreading center, which occurs
when two plates are pulling apart from one another. Spreading centers occur at mid-ocean
ridges and rift zones.
At these spreading centers, new crust is created to fill in the gap created as plates spread apart.
Since the Earth is not constantly getting larger, crust must be destroyed at other places on
Earth. These plate boundaries are convergent plate boundaries. At convergent plate
boundaries, two plates are pushing into one another. If the two plates are both continental
plates, large mountain ranges form. An example of this is the Himalaya mountain range in India,
Nepal, and Tibet.
If an oceanic and a continental plate meet, the oceanic plate is subducted beneath the
continental plate. This type of boundary creates a subduction zone.
A third type of convergent boundary involves the meeting of two oceanic plates. In this case, one
of the plates is subducted beneath the other.
Latitude and Longitude Review
Latitude (shown as a horizontal line) is the angular distance, in degrees, minutes, and seconds of a point
north or south of the Equator. Lines of latitude are often referred to as parallels.
Longitude (shown as a vertical line) is the angular distance, in degrees, minutes, and seconds, of a point
east or west of the Prime (Greenwich) Meridian. Lines of longitude are often referred to as meridians.
For example, our office on Galveston Island, Texas, USA, is located at 29 degrees, 16 minutes, and 22
seconds north of the equator, and 94 degrees, 49 minutes and 46 seconds west of the Prime Meridian.
Source: http://www.worldatlas.com/aatlas/imageg.htm
Lines of longitude all run through the north and south poles and cut the Earth in half. However, the lines
are not parallel to each other. The lines are labeled in degrees east and west of the prime meridian.
Degrees west are labeled as negative, while degrees east are labeled as positive. More information:
http://www.msnucleus.org/membership/html/k-6/uc/geography/2/ucg2_2a.html)
Use Earthquake data to model subduction zones:
1. Earthquake manganite and depth can help model the subduction zones at plate
boundaries:
a. http://www.iris.washington.edu/ieb/index.html
i. Use the right select options to select a region and number of
earthquakes
ii. Now click the “3D viewer button”