The alkaline magmatism evolution in the South American Platform: petrogenetic and geodynamical implications

Abstract

The project aims investigating the large number of alkaline rock occurrences present in the South American platform. This magmatic activity is found in and around the Paraná Basin in Brazil, Paraguay, Bolívia and Uruguay, but it is more concentrated in the former two countries. It started in the Permian- Triassic (250-240 Ma) and lasted up to the Oligocene (~39 Ma) times. Apart from its central purpose, which deals with the systematic mineralogical, petrological, geochemical, geochronological and paleomagnetic study of the numerous bodies, the project is also focused on three different aspects (1. The description of new occurrences of kimberlites in the northern part of Brazil; 2. The geochemical characteristics of the carbonatitic associations occurring in Brazil, Paraguay and Bolívia, and its correlation with similar rock-types cropping out in the African continent, particularly in Angola and Namibia; 3. the tectonic control and the emplacement of the alkaline bodies) that should improve the knowledge of the alkaline magmatism and will throw some light on the genesis and evolution of the alkaline rocks.The project is basically concentrated on research activities, and should also support field expeditions to different places in the mentioned countries and provide the necessary funds for the maintenance and up-grading of the microprobe and Ar/Ar laboratories. It will be carried out by Brazilian researchers, mainly from the Instituto de Geociências, and Italian workers. (AU)