Evolução morfo-sedimentar do sistema flúvio-lacustre “Lagoa Grande”, Camocim, Ceará, a partir de análises geo-históricas

Abstract

Paleogeography is a study object of Physical Geography studies, which one aims to understand at the heart of the environmental dynamic and its systematic, the evolution of the distinct types of natural systems. It is inside of this perspective that the temporal content manifests itself in the geographic space, being the structural-geology, geomorphologic, climate and anthropic forcing the responsible to the fluvial-lagoon landscape changes. Thus, the evolution of morpho-sedimentary studies in the coast zone of Ceará, by the synchronism of the geo-historical analysis, become essential to the achievement of the evolutive understanding, which has not been reached yet. With it, this doctoral project had as purpose identifies, characterize and analyze the evolution of the fluvial-lagoon system “Lagoa Grande”, localized at the municipality of Camocim. The initial search counted with the bibliographical survey and the compilation of the quali-quantitative and exploratory data. For sedimentary, historical-cartography and satellite images analysis was collected 5 samples, 50 maps and 7 historical documents and 10 satellite images by the Landsat MSS/TM historical series. Could be identified that Lagoa Grande has passed for synchronic and diachronic changes since the Flandrian period until now. Thereby, the tectonic, the geomorphology influenced by the climate and the human local activities have been reflecting the functioning of the landscape and in the different forms of sedimentary deposition. On this, the image digital processing made possible to visualize that the expansion of the Aeolic system is allied to the actual climate conditions, allowing Lagoa Grande to evolve constantly to the form of drowned river. Through of historical documents was notable from the XV century to the XX century the study area was represented as tributary of Rio Coreaú and closed or opened fluvial-lagoon system. Lastly, was noticed that the stratigraphy presented depositional layers formed through Flandrian and Post-Flandrian period, where the sediments exhibited marks of Aeolic, fluvial, intratide and lacustrine transports, with a presence of neoformed mineral clays indicating intense coastal dynamic. It is concluded that the paleogeography is able to integrate chronologically and geologically the formation and/or the evolution of different environmental systems. Therefore, Lagoa Grande present through the distinct paleo-indicators components and conditioners that shows a part of the littoral evolution of Camocim, Thereby, that the development about this subject serve as a way to verticalize, expand and consolidate the coastal evolutive studies in Ceará.