2017-06-162017-06-161982-12-29REYMÃO, Maria de Fátima Fernandes. Estudo físico-químico de hidróxi-fosfatos e minerais associados ocorrentes na Chapada de Pirocaua (MA) e no Morro de Jandiá (PA). 1982. 153 f. Dissertação (Mestrado) - Universidade Federal do Pará, Centro de Geociências, Belém, 1982. Programa de Pós-Graduação em Ciências Geofísicas e Geológicas.https://repositorio.ufpa.br/handle/2011/8712A lateritic profile rich in alumino-calcic and aluminum hidroxi-phosphates (Pírocaua, MA), and another also rich in alumino-oaloio and containning iron and calcium hidroxi-phosphates (Jandiá, PA) has been investigated in order to elucidate the formation of the secondary minerals and the trace element behaviour during tropical weathering. For such purposes it was decided to use X-ray diffratometry and chemical analysis and it was pointed out the applicability of infrared absorption spectroscopy: and differential thermal analysis for the mineral characterization. In order to relate the geochemical alterations it was included a theoretical thermodynamic study. lnfrared absorption spectroscopy and differential thermal analysis have been demonstrated to be valuables methods for studying minerals. Results are presented which demonstrate the usefullness of these techniques. These studies show that it is now possible to correlate differential hermal analysis and infrared data with that from other techniques (chemical analysis, X-ray diffraction patterns) and that the methods yields valuable supplemental information. Theoretical calculations and the use of thermodynamic data (standard free energie and solubility products) reveal some important conclusions about chemical equilibria, mineral formation, solubility and stability relations.Acesso AbertoGeoquímicaFosfatosMineralogiaFísico-químicaChapada de Pirocaua - MAMorro de Jandiá - PADissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA::GEOQUIMICA