Mariana is one of the geological features formed via subduction (WWF, 2017).  Prior to its formation, a plate overridden by an oceanic crust was forced sideways and below another plate overridden by an oceanic crust.

Question 17

The Mid Atlantic Ridge, a hilly feature located beneath the water, was formed through the deformation of plates, popularly referred to as the plate tectonics (Cann et al., 1997). Convection currents rose well above the mantle below the oceanic crust and formed a magma at the divergence point of two different plates.