Low order, sequential or non-massively parallel finite elements are generaly used for three-dimensional gravity modelling. In this paper, in order to obtain better gravity anomaly solutions in heterogeneous media, we solve the gravimetry problem using massively parallel high order finite elements on hybrid multi-CPU/GPU clusters. Parallel algorithms well suited for such hybrid architectures have to be designed. A new stochastic-based optimization procedure for the optimized Schwarz method is here presented, implemented and tuned to graphical cards processors units. Numerical experiments performed on a reallistic test case, demonstrates the robustness and efficiency of the proposed method and of its implementation on massive multi-CPU/GPU architectures.