Ironstones or petroplinthites are common materials in soils under humid tropical climate, generally defined as the result of Fe oxide accumulation in areas where the water table oscillates, and may exhibit considerable morphological variability. The aim of this study was to examine the internal structure and porosity of an ironstone fragment from a Petroferric Acrudox in Minas Gerais, Brazil, by computed tomography (CT) and conventional techniques. The sample analyzed had total porosity of 59.5 %, with large macropores in the […]

In northern and western landscapes of São Paulo State, plinthite and petroplinthite are features observed commonly above the cretaceous Adamantina Formation sandstones (Bauru Group). Two representative soil profiles with plinthic, petroplinthic and mottling features were selected in the local landscape to evaluate the mineralogical characteristics and to study their formation. The study was carried out at the foot of a mountainside in the Experimental Station Pindorama of the Agronomic Institute Campinas (IAC), in the north of São Paulo State, Brazil. […]

On the landscape of the Eastern Plateau, north of the State of São Paulo, Brazil, there are ferricretes in different elevations. Although these features are relatively frequent over the cretaceous sandstone (Adamantina Formation, Bauru Group), little investigation has been carried out on their genesis. A morphological study at different levels of observation was conducted in order to elucidate the genesis of ferricretes (plinthite and petroplinthite), occurring at the toeslope of a landscape where soils with argillic horizon predominate, at the […]