Alkaline Rocks and Carbonatites of the World

Funded by HiTech AlkCarb - New geomodels to explore deeper for Hi-Tech critical raw materials in Alkaline rocks and Carbonatites

Brazil

Brazil

With over 100 complexes, more than 20 of which include carbonatite, Brazil is notably well endowed with alkaline rocks. Vast areas, particularly in the Amazon Basin, are not yet thoroughly explored or are obscured by a thick lateritic cover, so that further occurrences are certain to be found. Many intrusions have been exploited economically, particularly those with carbonatite, making Brazil the world's foremost producer of Nb and a major producer of phosphate, vermiculite and rare earths.
A very full review of Brazilian alkaline rocks and carbonatites has been given by Ulbrich and Gomes (1981) and J. G. Valenca has written an unpublished review paper. Rodrigues and Lima (1984) give a brief account of the carbonatites of Brazil and have tabulated the main features of 21 intrusions; they also list all occurrences of alkaline rocks, including circular structures, detected from the air, which may prove to be alkaline intrusions. Particularly useful compilations for the Rio de Janeiro-Sao Paulo area are to be found in Lima (1976) and Liu et al. (1976). Herz (1977 and 1978) has reviewed the ages of the alkaline rocks of southern Brazil and related them to associated basaltic volcanism, the opening of the Atlantic Ocean, and movement of the South American Plate. Asmus (1978) lists the ages of many alkaline complexes and discusses them in terms of oceanic and continental fracture systems, while the plate tectonic setting of alkaline igneous occurrences south of latitude 15°S are discussed by Almeida (1983). Numerous ages are given by Amaral et al. (1966).

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