Submitted by Divis??o de Documenta????o/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T14:59:17Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Disserta????o - Marcel Silva Passos.pdf: 18087958 bytes, checksum: 7ce5b597a99561e6c73f24a81086a760 (MD5) Approved for entry into archive by Divis??o de Documenta????o/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T14:59:32Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Disserta????o - Marcel Silva Passos.pdf: 18087958 bytes, checksum: 7ce5b597a99561e6c73f24a81086a760 (MD5) Approved for entry into archive by Divis??o de Documenta????o/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-02-20T14:59:50Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Disserta????o - Marcel Silva Passos.pdf: 18087958 bytes, checksum: 7ce5b597a99561e6c73f24a81086a760 (MD5) Made available in DSpace on 2017-02-20T14:59:50Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Disserta????o - Marcel Silva Passos.pdf: 18087958 bytes, checksum: 7ce5b597a99561e6c73f24a81086a760 (MD5) Previous issue date: 2016-04-15 CAPES - Coordena????o de Aperfei??oamento de Pessoal de N??vel Superior The Solim??es River, at the confluence zone with the Purus River (Western Amazonia) features 3 levels of Pleistocene-Holocenos river terraces, informally called Superior (TS), Intermedi??rio (TI) and Inferior (TInf), defined in this study based in remote sensing data, sedimentology, stratigraphy and geochronology. In general, the terraces display symmetrical distribution, form parallel tracks to the river and extend for tens of kilometers. Located between the elevations 15-75 m, display aged 750-204,000 years BP and internally consist of interbedded sand and mud layers (silt and clay) forming pairs of Stratification Heterolytic Leaning (EHI). The TS (55,000 to 204,596 years BP) is characterized by raised ridges and depressions, showing dendritic drainage patterns to subdendritic and traces of old lines of lateral accretion. The terraces TI (28,400 to 37,240 years BP) and TInf (750-9315 years BP) are part of the active floodplain of the river, subject to seasonal flooding. TI provides relief plan with gentle undulations, displaying rows of lateral accretion and dozens of lakes with elongated shapes, rounded and curved, while the TInf is the closest unit to the main channels, making the marginal bars and islands, stands out for most density lines accretion and lakes. The symmetry of the levels of the terraces of the Solim??es River, as well as the features of paleochannels and the presence of EHI, show your past meandering fluvial style that prevailed in the Late Pleistocene, leading to the conclusion that the migrated channel for tens of kilometers. However, recent data show that this river has a high degree of stability, defined primarily based on the channel low migration rate (around 0.32% / year), and by the presence of islands and marginal bars and muddy fitoestabilizadas that define the current anastomosing-anabranching style. The change of fluvial style in the Pleistocene-Holocene boundary can be mainly related to climatic variations, tectonics and glaciostatic. The rise in the sea to the current level, between 18,000 and 6,000 and years BP, blocked the mouth of Solim??es-Amazonas river system, causing a decrease in slope and greater input of fine sediments, which in combination with the increased humidity (which allowed phytostabilization the islands and margins) made this system more stable and allowed the installation of the current anastomosing-anabranching style. The predominance of this style can be extended to the east, to the confluence region with the Madeira River. O Rio Solim??es, na zona de conflu??ncia com o Rio Purus (Amaz??nia Ocidental), apresenta 3 n??veis de terra??os fluviais pleistocenos-holocenos, denominados informalmente de Superior (TS), Intermedi??rio (TI) e Inferior (TInf), definidos neste estudo com base em dados de sensores remotos, sedimentol??gicos, estratigr??ficos e geocronol??gicos. Em geral, os terra??os exibem distribui????o sim??trica, formam faixas paralelas ao rio e se estendem por dezenas de quil??metros. Localizam entre as cotas de 15 a 75 m, exibem idades entre 750 a 204.000 anos AP e, internamente, s??o constitu??dos por intercala????es de camadas de areia e lama (silte e argila), que formam os pares da Estratifica????o Heterol??tica Inclinada (EHI). O TS (55.000 a 204.596 anos AP) ?? caracterizado pelo relevo de cristas e depress??es, exibe padr??es de drenagem dendr??tico a subdendr??tico e vest??gios de antigas linhas de acre????o lateral. Os terra??os TI (28.400 a 37.240 anos AP) e TInf (750 a 9.315 anos AP) fazem parte da plan??cie aluvial ativa deste rio, estando sujeitos ??s inunda????es sazonais. O TI apresenta relevo plano com suaves ondula????es, exibindo linhas de acre????o lateral e dezenas de lagos com formas alongadas, arredondadas e curvadas, enquanto o TInf ?? a unidade mais pr??xima aos canais principais, compondo as barras marginais e ilhas e, se destaca pela maior densidade de linhas de acre????o e lagos. A simetria dos n??veis dos terra??os do Rio Solim??es, bem como as fei????es de paleocanais e a presen??a da EHI, evidenciam o seu pret??rito estilo fluvial meandrante que predominou no Pleistoceno Superior, permitindo inferir que o canal migrou por dezenas de quil??metros. Entretanto, os dados atuais mostram que este rio tem um elevado grau de estabilidade, definido principalmente com base na baixa taxa de migra????o dos canais (em torno de 0,32%/ano), bem como pela presen??a de ilhas e barras marginais lamosas e fitoestabilizadas que definem o atual estilo anastomosado-anabranching. A mudan??a do estilo fluvial no limite Pleistoceno-Holoceno pode ser relacionada principalmente as varia????es clim??ticas, tect??nicas e glacioeust??ticas. A subida do mar at?? o n??vel atual, entre 18.000 e 6.000 e anos AP, bloqueou a foz do sistema fluvial Solim??es-Amazonas, provocando a diminui????o da declividade e maior aporte de sedimentos finos, que em associa????o com o aumento da umidade (que permitiu a fitoestabiliza????o das ilhas e margens) tornaram este sistema mais est??vel, e permitiu a instala????o do atual estilo anastomosado-anabranching. A predomin??ncia deste estilo pode ser estendida a leste, at?? a regi??o de conflu??ncia com o rio Madeira.