The diagram is a cross section showing the Nazca Plate (an oceanic plate) subducting beneath the South American Plate (a continental plate). This region is an example of oceanic-continental convergence.
A diagram.Short description, A diagram.,Long description,
The Nazca Plate contains oceanic crust covered by water in the lithosphere, and above the asthenosphere. The South American plate contains continental crust in the lithosphere, and above the asthenosphere. At the fault between them, the Nazca plate is pulled under the South American Plate. A volcanic arc, a line of volcanoes, sits where the two plates meet.
Question
Why does oceanic-continental convergence produce a volcanic arc?
Answer options with 4 options
A.
Continental crust is heavier than oceanic crust, so the continental crust sinks, melts, and forms a volcanic arc.
B.
Oceanic crust is less dense than continental crust, so the two plates slide sideways past each other and form a volcanic arc.
C.
Continental crust has the same density as oceanic crust, so the two plates collide, buckle under pressure, and form a volcanic arc.
D.
Oceanic crust is denser than continental crust, so the oceanic crust sinks and melts, and the magma produced rises up to form a volcanic arc.
1 answer