Let S be a closed surface of genus g ≥ 2 and let ρ be a maximal PSL(2, R) × PSL(2, R) surface group representation. By a result of Schoen, there is a unique ρ-equivariant minimal surface Σ in H 2 × H 2 . We study the induced metrics on these minimal surfaces and prove the limits are precisely mixed structures. In the second half of the paper, we provide a geometric interpretation: the minimal surfaces Σ degenerate to the core of a product of two R-trees. As a consequence, we obtain a compactification of the space of maximal representations of π1(S) into PSL(2, R) × PSL(2, R).