The Lavras do Sul Shoshonitic Association is related to the early stages of post-collisional alkaline magmatism in the Brasiliano Orogenic Cycle in southern Brazil. Their magmas were produced through melting of a litospheric mantle metasomatized during a previous subduction. The LSSA is composed of co-genetic rocks derived from magmas evolved by fractional crystallization which show a large silica range. These features are quite adequate for interpretations based on the sliding normalization technique, which allows comparing magmas with different degrees of differentiation in order to evaluate and discuss their potential sources, petrogenetic mechanisms and geotectonic settings. The LSSA composition was used as the pattern for normalizing data available in bibliography for the Late Precambrian post-collisional Tismana pluton, the 1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield, the monzonitic series from the Variscan Tormes Dome, the post-collisional potassic and ultrapotassic magmatism in northern Tibet, and the Baranadag pluton in Central Anatolia, Turkey. This procedure allowed the identification of two distinct geochemical trends: (i) Zr-Nb-Ti-Y-REE enrichment, and (ii) increasing of Rb-K2O with concomitant Nb decrease. The former probably reflect the participation of an astenospheric component, whilst the second trend is related to crustal assimilation. The Nb-Rb-K2O diagram, used for values normalized by this technique, is proposed for discriminating post-collisional shoshonitic associations with different contributions of astenospheric and crustal materials.