A PROVÍNCIA PEGMATÍTICA ORIENTAL DO BRASIL À LUZ DOS CONHECIMENTOS ATUAIS

Resumo

Thís paper deals with the present knowledge level about pegmatites from the huge brazilian eastern pegmatitic province. Attention was given to: systematíc and metamorphic control of pegmatites; metallogenetic age and geological setting of the province; structure of the rocks governing the morphology of pegmatítes; primary mineralogy and geochemistry; and the genetic links between granites and pegmatites. This was dared even having in mind the actual size of the province and the scarcity of reliable evidences at the present time. The pegmatites throughout the Araçuaí district seem to have evolved from biotitic granites and forceful iniected their host metamorphic rccks. However not all seem to point to the same crustal depths of emplacement and crystallization. So while the Itinga pegmatítcs, carrying petalite and spadumen + quartz or spodumen only, were emplaced in andalusite and cordierite schists of intermediate depths, the Coronel Murta ones, lacking in petalite, are found in kyanite schists from deeper crustal levels. The genetic links among at least some granites and pegmatites, in the Galiléia region, seem to be like those of Coronel Murta. The same can not be said about the pegmatites from Marilac where up to the present time no one of the genetic links with granites, not even in the field, could be traced. In the last two arcas, at least in the Marilac one, the metamorphism graded up to the anatetic field. The metallogcnetic potential for Li, Rb, Cs and Ta can be increasingly arranged as follows: Marilac, Galiléia, Coronel Murta, and Itinga the last one being the best know and promising spot.