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The Early paleogeographic reconstructions of the South American basement show a series of metamorphic rocks of Precambrian-Early Paleozoic ages surrounding the southwest margin the South American Platform (Almeida, 1970, 1971, and recent review of 2000). These peripheral exposures of metamorphic rocks correspond to the outcrops of the Sierras Pampeanas, a series of basement blocks uplifted during the Andean orogeny (González Bonorino, 1950; Caminos, 1979). These basement outcrops are west bounding the Rio de la Plata Craton, and they are characterized by discontinuous exposures over 1,600 kilometers from 26ºS to 39ºS latitudes. Since the early proposals that considered this metamorphic basement as the result of the collision between Rio de La Plata and a Pampean block at the end of the Proterozoic (see Ramos 1988, and cites there in), a large subsequent advance in the geological knowledge permitted the definition of a complex history of deformation, metamorphism and magmatism. The objective of this review is to update the large amount of information available about the basement of the Sierras Pampeanas and adjacent terranes in a coherent tectonic framework in order to propose a more precise reconstruction of Rodinia in the analyzed sector following recent proposals of Li et al. (2008) and others, where this cratonic basement is faintly recognized. These basement outcrops have been integrated in a large cratonic block defined as Pampia (Fig. 1) that occupied the central and northern region of Argentina (Ramos and Vujovich, 1993), which Brito Neves et al. (1999) and Almeida et al. (2000) among others, located bounded by the Amazonian and Rio de La Plata cratons and the Paranapanema (or Parana) cratonic block (Mantovani and Brito Neves, 2005). The basement of Sierras Pampeanas encompasses two magmatic belts with arc affinities. The eastern belt comprises a late Proterozoic Early Cambrian magmatic and metamorphic belt bounded by ophiolitic rocks known as the Pampean orogen. The western belt comprises a similar belt of Ordovician age named as the Famatinian orogen. The first comprehensive evolution of the basement of the eastern Sierras Pampeanas was presented by Kraemer et al. (1995) who explained the geological history of this region as the result of the collision of the Pampia terrane against the Rio de La Plata craton during the latest Proterozoic. This study emphasized the important orthogonal deformation observed in the kinematic indicators of the large megashears that crossed the basement with an approximated N-NW trend. New geochronological data presented by Rapela et al. (1998) extended the collision up to the Early Cambrian. Subsequent works along the western margin of the western Sierras Pampeanas defined a magmatic arc of mainly Ordovician age interpreted as the upper plate of a subduction zone developed between the basement of Precordillera and the Pampean block (Ramos et al., 1986). Although most of the research performed in those days was concentrated in the relationships between the different magmatic arcs, their geochemical and isotopic composition, and the differences in ages between the eastern and western Sierras Pampeanas, only little attention has been paid to the extent, boundaries and precise composition of the Pampia cratonic block.