Imagine a convergent plate boundary where a oceanic and contintental plate meet.?

Question

1) What type of magma is erupting at the surface in this environment? why?

2) what type of volcano is created here? why?

Answer 1

If magma (lava) is erupting, it would most likely be mafic lava because it would emanate from the subducting oceanic plate.  Oceanic plates are comprised of basalt which produces mafic lava.

Below is a good diagram:

http://geology.com/nsta/convergent-plate...

The type of volcano would be volcanic arcs comprised of a string of shield volcanoes.  This is because shield volcanoes are built of fluid (thin and runny) lava flows.  Mafic lavas are fluid lavas.