Abstract
The metalogenic epochs of the main mineral deposit groups were defmed with base on the ore's ages of the 194 main brazilian mineral deposits. Mineral deposits are rare on epochs that: (1) preced the beginning of juvenile accretion peak periods and/or (2) of cooling of rocks formed during each of the main brazilian thermo-tectonic events. Deposits are more frequent on epochs that are coincident or immediatly younger than these peak periods. The most important metalogenic epoch, with about 30% of the selected deposits, is between 50 Ma and the Recent, and corresponds to the formation of supergenic and/or residual and placer deposits. Brazilian's volcanogenic (VHMS), Mississippi Valley (MVT) and mesothermal gold-lode deposits have discordant ages as compared with their equivalents in other countries, while deposits believed to be SEDEX have concordant ages. With the exception of Urucum, the primary iron and manganese ores of brazilian deposits are Archean. Primary tin deposits from Amazonas, Amapá and Goiás States cluster between 1500 and 2300 Ma. Tin deposits from Rondônia and Mato Grosso are more recent and most formed between 1000 and 1600 Ma, in sequence with the other groups of tin deposits. Uranium deposits vary on genetic model and ages, due to the mobility of the element in ali geologic environments. Most part of brazilian deposits of phophate, titanium, niobium, Rare Earths, diamond in kimberlites and of amethist formed during the Mesozoic, and arte genetically related to the alkaline and basaltic magmatism that affected the brazilian territory in this period. Gemstone (tourmaline and acquamarine), tale and magnesit deposits are more frequent in the Brasiliano period. Gipsite, silvite and barite occur in Senonian to Aptian evaporites.
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