Spallation reactions are generally considered to proceed in two stages: a cascade stage followed by an evaporation stage. Light charged particle (lcp) spectra indicate that such particles are produced by both stages. The mechanism of production in the cascade stage is still not fully understood. Using the improved versions of the Liège Intra-Nuclear Cascade model and of the ABLA evaporation model, we have recently shown that lcp's are presumably produced by some kind of dynamical coalescence process, by which a fast particle of the cascade drags a few other nucleons. In the very recent years, precise measurements of the production of heavier clusters have been performed. We improved and generalized our production models for the heavier clusters, up to A=10 and we reached good agreement with experiment. These results strongly suggest that the dynamical coalescence mechanism applies to heavy clusters. The importance of these data for spallation neutron sources and accelerator-driven systems is underlined.