The tectonic-magmatic event at the border of the Paraná basin in southera Brazil (Mato Grosso do Sul State) and Eastern Paraguay is evidenced by the existence of several foci of alkaline rocks. The recent accumulation of knowledge on this magmatism, active between the Permo-Triassic and Oligocene, makes it crucial that it be reviewed and leads to an updated proposal for assembling the known occurrences mainly on the basis of petrographic, geochemical and geochronological evidence. Despite unsatisfactory information on some occurrences, the available data allow definition of six provinces (Alto Paraguay, Rio Apa, Amambay, Central, Misiones and Asunción), each characterized by remarkable differences in rock composition and time of emplacement into the crust. Although little work has been done in Paraguay on the relation between geographic distribution of the alkaline magmatism and tectonic elements, three main types of association can be suggested: a) cratonic margins or tectonically stable áreas, for example, the Alto Paraguay and Rio Apa Provinces; b) structural ares or tectonic alignment, exemplified by the Amambay Province, and c) continental rift, as is the case for the Central, Misiones and Asunción Provinces.
