Combinación de bandas y clasificación no supervisada de imágenes satelitales para la identificación de paleoredes de drenaje en el sudoeste bonaerense, Argentina

Abstract

The aim of this study is to delimit to paleodrainage networks in the southwest of Buenos Aires Province (Argentina), applying combination bands and an unsupervised classification in Landsat 7 ETM+ satellite imagery. By using a false-color image obtained with bands 2, 3 and 4, assigning them to blue, green and red filters, respectively, it was able to identify water bodies of different extension and deepness. An unsupervised classification using two bands 4 from different dates, allowed defining five classes, the class that corresponds to the lacunar bodies was extracted. A visual analysis of the false-color image allowed recognizing that these water bodies are connected, in some cases, to each other through narrow paleobeds. These paleobeds exhibit hydromorphic soils, though more evolved-soils were distinguished as well. Two drainages networks were defined with their summits unconnected with the Australes Range rocks, which constitute the maximum altimetry in the region. In turn, their base levels are associated with endorreic depressions. The hydrologic basin 1 present an East-West alignment, is well-developed, integrated and have its base level would be located in the Hucal valley. The hydrologic basin 2, less developed than the basin one, present a South-North orientation and the base level would be in the Epecuén area of the Encadenadas del Oeste System. The age of these paleodrainage systems would be not older than late Miocene.