2019-08-302019-08-302012-03-07CAMPOS, Amélia Carolina Pimenta Parente. Geocronologia e Paleoambiente de rochas carbonáticas do grupo tucavaca (Bolívia), com base nos isótopos de Sr, C E O. Orientador: Moacir José Buenano Macambira. 2012. 92 f. Trabalho de Curso (Bacharelado em Geologia) - Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2012. Disponível em: http://bdm.ufpa.br/jspui/handle/prefix/1868. Acesso em:.http://bdm.ufpa.br/jspui/handle/prefix/1868The study of carbonate rocks is very important for the understanding and characterization of hydrocarbonate deposits, since 50% of world oil is associated to these rocks. Bolivia is a great example, because it is today the largest exporter and has the second largest natural gas deposit in South America. The Tucavaca Group occurs in a wide area of eastern Bolivia, denominated Chiquitos-Tucavaca Aulacogen, which is considered an aborted triple junction rift, also known as Tucavaca belt. The stratigraphy of the Tucavaca basin is represented by a sequence made up, from the bottom to the top, of the Boqui Group, followed by the Murcielago Group and the Tucavaca Group. The Tucavaca Group is composed of conglomerates of the Pacobillo formation, carbonates of the Pororó formation, sandstones of the Bocamina formation and shales, mudstones and siltstones of the Pesenema formation. The group in question is devoid of paleoenvironmental studies and the age of deposition is still uncertain. So, C, O and Sr isotopes studies were carried on carbonates of the Pororó formation. For this purpose, carbonate samples were previously submitted to petrographic and X-ray fluorescence analyses in order to select the most appropriate samples for isotopic analyses. The carbonates studied here were individualized in three microfacies: laminated fine dolomite, fine dolomite and dolomitic breccia. The stable isotope studies were performed on all samples of the sequence and the samples TUCA – 1, TUCA – 3 and TUCA – 8 were selected for Sr analysis. Values of 13C and 18O are negative, ranging from -5.24 to -2.56‰ and -7.16 to -4.59‰, respectively. 87Sr/86Sr ratios are 0.707712 (TUCA – 1), 0.707925 (TUCA – 8) and 0,710183 (TUCA – 3). 18O values are within the limit set as a parameter of Neoproterozoic carbonates considered isotopically preserved, determined such as >-10‰. The negative values of 13C indicate low or no biological activity in the ocean and the possible incorporation of organic matter in carbonate sediments. The 87Sr/86Sr ratios place the samples at the end of Neoproterozoic (Ediacaran), between 580 and 560 MaAcesso AbertoGeologia IsotópicaGrupo TucavacaCarbonatos neoproterozóicosPaleoambienteCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIATrabalho de Curso - Graduação - Monografia