Análise morfoestrutural na porção leste da Ilha do Marajó/PA

Analysis of drainage basins combining remote sensing and cartographic data might provide significant information for the recognition of morphostructural lineaments and, thus, understanding structural frameworks. This type of approach applied to an area of eastern Marajó Island revealed that the modern drainage basins are tectonic controlled. The three drainage basins characterized herein, which include the rio Arari, Camará and the Paracauari basins, display several anomalies that are consistent with this interpretation. These mostly include rapid changes in patterns that range from trellis, rectangular, multibasin to sub-parallel; channels that are connected in straight angles; rapid changes from meandering to straight channels; localized meandering and highly asymmetric basins. Additionally, comparisons between modern drainages and paleochannels indicate a drastic change from main east/north to southeast flowing basins. These characteristics are consistent with previously proposal of a slight subsidence of the eastern Marajó, as a result of the establishment of Marajó bay. Palavras-chave: anomalias de drenagem, tectônica, paleocanais, Ilha do Marajó, evolução quaternária.