2019-08-222019-08-222010-10-06CARVALHO, Aliane Trindade. Sedimentologia, mineralogia e geoquímica dos sedimentos do pântano Mauritia na Serra Sul, Carajás (Pará). Orientador: Marcondes Lima da Costa. 2010. 129 f. Dissertação (Mestrado em Geologia e Geoquímica) – Instituto de Geociências, Universidade Federal do Pará, Belém, 2010. Disponível em: http://repositorio.ufpa.br/jspui/handle/2011/11492. Acesso em: .https://repositorio.ufpa.br/handle/2011/11492Lakes and lake sediments are frequently in terrain with ferruginous lateritic crusts in the Amazon region, which present themselves as important records of paleoenvironmental changes in this region. These sediments can be found in great profusion in Carajas, either in Serra Norte as in the Serra Sul, and have been objects of research, which focused on palynological studies, with little information on the mineralogical and chemical characteristics. This study employed the techniques of sedimentology, mineralogy, geochemistry, stable isotopes and radiocarbon to investigate these sediments in an area known as Mauritia swamp in Serra Sul, Carajas, in the south of Pará. A 466 cm sedimentary sequence has been drilled with the aid of a hand core probe type Livingstone. According to the lithological variations and their possible relationship with depth ranges 23 samples have been taken and submitted to the following analysis: particle size by laser particle sizer, XRD mineralogy, micromorphology by SEM/EDS, quantification of the matter organic, respectively, by method of Walkley-Black and FTIR, organic and inorganic carbon, δ13C (organic matter and carbonate) and δ18O (carbonate) and radiocarbon dating. The sequence shows a silt-clay aspect, in alternated layers, indicated by variation in color (shades of brown and gray) highlighting two sedimentary cycles that started its deposition for at least 52,000 years BP. Sediments are predominantly silty, with a little fine sand and clay largest contribution with average grain size ranging from 9.6 to 52.3 μm and average diameter (50%) around 33 μm. Sediments are composed of quartz, opal, kaolinite, goethite, siderite, anatase, and sporadic presence of gibbsite, barite, talc and/or chlorite. And amorphous siliceous spicules (opal), cauixi, as well as diatom fraagments, are concentrated in upper 138 cm. The contents of carbonaceous organic matter (Corg) are high, ranging from 3.39 to 89.6% with an average of 49.08%, corresponding to very high LOI values. The remaining fraction is represented by SiO2, Fe2O3, Al2O3 and TiO2 distributed along the sequence with large variations after the distinct sediment layers. Likewise, the near absence of K2O, P2O5, MgO and CaO, are also inherent characteristics of the sediments of Mauritia swamp. This chemical composition does not store any similarity to the composition of crustal rocks and much less with the shales, only matched the iron-aluminous lateritic crusts. The isotopic composition of δ13C and δ18O indicate, beside the mineralogical data and content of OM, that sedimentation occurred under different climatic conditions ranging from semi-arid to humid and warm, made of plants physiologically and ecologically distinct. The sedimentological, mineralogical, geochemical, radiocarbon and stable isotopic data indicated that the Carajas region has experienced marked climatic changes of semi-arid to humid and hot from the late Pleistocene to Present.Acesso AbertoGeoquímicaSedimentologiaSerra dos Carajás - PADissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIASMINERALOGIA E GEOQUÍMICAGEOQUÍMICA E PETROLOGIA