Geochronology of petroplinthites and the evolutionary relationship between the Dissected Plateau of Tocantins and the Mangabeiras Plateau (east-central TO, Brazil)

• Grant number: 25/11684-5
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: August 01, 2025
• End date: July 31, 2029
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Pablo Vidal Torrado
• Grantee: Sergio Vieira Rozendo Júnior
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 24/05549-5 - Soil-Landscape relationships and sustainable management of Petric Plintosols in the State of Tocantins (Brazil), AP.TEM

Abstract

The central-eastern portion of the state of Tocantins encompasses a geomorphological mosaic revealing a complex evolution of the landscape. Between the Tocantins Dissected Plateau, in the central region of the state, and the Mangabeiras Plateau, on the border with Bahia, different terraced surfaces are formed, comprising the Middle Tocantins River Valley Depression, the Jalapão Terraces, the Jalapão Low Plateaus, as well as preserved witness hills. This heterogeneous relief sits on sandstones from the Urucuia Group (São Francisco Basin) and sandstones, siltstones, and shales from the Pimenteira Formation (Parnaíba Basin), revealing little lithological variation. Except for the Tocantins Dissected Plateau, petric plinthosols are not so common in this part of the state, but remnants of petroplinthites and ferruginized sandstones are still found protecting some summit surfaces. Thus, this thematic project requires a direct doctoral candidate who can unravel the geomorphological evolution of this area in time and space. To do so, the candidate must travel throughout this landscape to find profiles of concrecionary or lithoplintic petric plinthosols and collect petroplinthites rich in goethite, hematite, and/or manganese oxides ideal for (U-Th)/He and 40Ar/39Ar dating methods. Mineralogical, geochemical, and micromorphological analyses will be performed in laboratories in Brazil, and subsequently, grains of Fe and Mn oxides will be selected and dated abroad in specialized laboratories in Australia and the United States. (AU)