GEOMORFOLOGIA - seplan - Governo do Estado do Tocantins

Abstract
This report and the Geomorphological map attached are about the study
and cartography of the relief of part of the State of Tocantins, Federal Unit of the
Northern Region of Brazil. The mapped area corresponds to portions of the topografic
Sheet SB.22-Z-B Xambioá, previously mapped at scale 1:1.000.000 by
RADAMBRASIL project and existent at scale 1:250.000 in SEPLAN’s archives. The
area is limited at the North by parallel 6º00’00” and at the South by parallel 7º00’00”
of latitude South of Equator, at the West by Araguaia River and the East by Meridien
48º00’00” west of Greenwich. The report presents, under methodology considerations,
the hierarquical ordering of geomorphological facts, identified trough Landsat-5 imagery.
It discusses the available bibliographie contribution, conparing it to the results
obtamed in the present survey. Based on similarity of relief forms, relative altimetry,
genetic characteristics and watersheds conformation, three Morphostructural Domains
are defined in the area: Bacias Sedimentares Paleo-mesozóicas e Coberturas Meso-
cenozóicas (Paleo-mesozoic and Meso-cenozoic Sedimentary Basins),
Embasamentos em Estilo Complexo e Faixas de Dobramentos (Complex Stile
Basements and Folding Belts), and Azonal das Áreas Aluviais (Azonal from Alluvial
Areas); two Geomorphological Regions: Planaltos da Bacia do Parnaiba (Parnaíba
Basin Highlands) and Depressão do Araguaia-Tocantins (Araguaia-Tocantins
Depressions); and three Geomorphological Units: Planalto Residual do Araguaia
(Highlands Araguaia’s Residual), Depressão do Araguaia (Araguaia’s Depression)
and Chapadas do Meio-Norte (Middle-North Plateus), besides the Azonal Units
characterizad by Planícies e Terraços Fluviais (Fluvial lowlands and Terraces). It
analyses the different factors that characterize relief evolution. It recognizes several
erosive phases, resulting in the formation of pediment. It refers to the opening of
folded reliefs and to the interference of a recent techtonic movement over drainage
and planed surfaces. It assesses the relief forms and suggets better uses of land. It
analyses road tracing, fluvial navigation, the existense of sites favourable to the
implantation of weirs, hydroeletric power plants and dams for water collection and
suggests plans with the possibility of ocorrence of mineral ores.