Uso integrado de dados de sensoriamento remoto para o estudo da geologia e geomorfologia da área da foz rio Tapajós, Santarém, Pará

Abstract

The Amazon plain is an important and strategic region of the world for scientific-technological development of Brazil. The scientific research point of view it knows little of the geology and geography of the region. The use of satellite images can be regarded as an indispensable tool to boost progress in this direction. In this context, the main objective of this paper is to present the details of geomorphology and geology of the mouth of the Tapajós River, between the 2nd 20 S to 40 S 2nd and meridians of 54, 35 W to 55 05 W and make a temporal analysis of the depositional history of this complex river system, located in the city of Santarém, Pará, In general, the methodological approach implemented was characterized by intense literature review, steps pre image processing, lifting steps field, a more significant step processing and multi-temporal analysis of satellite images. The data used in this research include images from the Landsat series, orthorectified Landsat images obtained at the University of Maryland site, topographical data Radar interferometry Shuttle Radar Topography Mission (SRTM), and radar mosaic picture JERS-1 SAR. Treatment and digital processing of orbital images were performed in 10.1 and PCI Software Arc GIS (Arc Map 9.2). In the western part of Pará emerge few lithostratigraphic units of regional distribution, essentially these are representatives of the rocks of the land Alter do Chão formation of Meso-Cenozoic age, and younger sedimentary terrains of Cenozoic plain of the Amazon and Tapajos rivers, modern alluvial deposits and detrital-lateritic covers. Among these regional geomorphological units only two matters within the study area: the Amazon Plain and Plateau relegated from Amazon. The visual interpretation of the set of images generated in this study allowed to obtain more detailed information than those available regionally, including some physiographic features, geomorphological and geological study of the area. In this study it was possible the delineation and characterization of at least three (03) distinct geomorphological areas: the Amazon floodplain / Tapajós, the River Valley area Dissected Tapajós and the Tablelands Pediplanizados. The analysis of all the associated information directly to systematic field surveys enabled the recognition, individualization and characterization of three (03) distinct geological units: the study area dominate lithologies associated Alter do Chão Formation and deposits of unconsolidated Cenozoic sedimentary (old and new) and modern alluvium. There are also less common-materials associated with the lateritic deposits-coverages debris. The information field and the numerous geological caminhamentos and visited spots, allowed the organization and presentation of the general stratigraphy of the study area and the stratigraphic correlation between the various profiles of rocks belonging to Alter do Chão Formation. With regard to the results achieved in the multi-temporal analysis of Landsat images , aimed at establishing the depositional evolution ( accretion rate and erosion) of the study area , in the study period (1975 and 2007) and respecting the limitations presented it was possible to state the region of the Tapajos bar showed dominance of erosion (positive erosion rate ) , and on the other hand, the fluvial islands on the Amazon River show depositional process of growth ( accretion ).