The plate boundary that doesn't involve magma is the transform plate boundary. However, there's another boundary plate where magma is not involved, it's an specific type of convergent plate boundaries and its the collision between two continental plates.
Explanation:
In the case of transform plate boundaries, the movement between the plates is just horizontal and there is not a possibility to magma to ascend because they are not creating a space to allow the rise of magma and there is not a plate subductng and melting as in the case of divergent and convergent boundaries respectively.
For the case of the convergent boundary where the collision is between two continental plates, theres is not magma involved because none of the plates goes down under the other, there is not subduction and there is not melting to generate magma ascent. In this cases there is a big crust strain that forms very high mountains as in the case of the Himalayan mountains.
The answer is the Transform Boundary. There are three kinds
of main types of tectonic plate boundaries and aside from Convergent, Divergent
there is also transform boundary. Some called it the sliding because the two plates
slide past each other that why earthquakes occur mostly in transform boundary. The divergent is describe as dividing and
other convergent called colliding.
