Atividade neotectônica em torno do lineamento transbrasiliano costa oeste do Estado do Ceará – Nordeste do Brasil: evidências através de índices morfométricos.

Abstract

The Transbrasiliano Lineament (LTB) is a megastructure of Neoproterozoic age (Braziliano Cycle) with continental dimension and NE-SW trend that cuts the Brazilian territory by about 2700km.With in the context of the Borborema Province, the LTB played along with other structures great influence in the installation and geohistory of the sedimentary basins of the Parnaíba Province. Therefore, the present study has the purpose of investigating possible features of tectonic deformations from the morphothectonic analysis, through the use of parameters that quantitatively determine the physical characteristics of the drainage network. The area is located on the west coast of the state of Ceará, encompassing the adjacencies of the Transbrasiliano Lineament (LTB). The applied methodology was supported by geoprocessing techniques and was based on the analysis of morphometric indexes: relation slope extension (RDE), asymmetric factor (Af), sinuosity of slope of valley (Svv) and integral hypsometric (Hi). These indexes used together allowed inferring the index of tectonic activity (Iat) which shows values consistent with the influence of these deformations in the region. It was verified that from the values obtained from the Iat the sub-basins Grande lagoon, Prata stream, Poeira stream and Trairí river indicated a high tectonics, the sub-basins Forquilha lagoon, Jijoca lagoon, Zumbi river, Aracatimirim river and Cruxati river presented high to moderate intensity and with moderate intensity Acaraú river, Aracatiaçú and Mundaú. Therefore, this work presented the importance of geoprocessing techniques and morphometric analyzes, which are very efficient in the results obtained under the neotectonic approach.