Geomorphological evolution of the Lower Valley of Ribeira de Iguape River and implications for the Holocene peatlands genesis

• Grant number: 24/03483-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: August 01, 2024
• End date: July 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Pablo Vidal Torrado
• Grantee: Luis Felipe Ferreira Batista
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Fluvial plains of meandering rivers presents features and environments where water and/or sediments accumulate, whether organic or inorganic. Saturated and poorly drained environments are conductive to the accumulation of organic matter and if this occurs in an intense and stable way over time, it can give rise to peatlands. The soils of peat ecosystem are Histosols, which are important carbon reservoir and emitters of methane gas, storing around 30% of the carbon in soils around the world. In Brazil, most studies peatlands are focused on highland environments. In the southern coastal plain of São Paulo State, moreprecisely in the Low Ribeira de Iguape River (LRIR), around 173 thousand acres of Histosolswere mapped in reconnaissance scale surveys, which characterizes the region as one of thelargest areas of occurrence of these soils on the South American continent. This plain wasaffected by two marine transgressions (Late Pleistocene and Holocene), which change the baselevel and strongly influenced the formation of sedimentary deposits and related relief forms. Inthis project, it is proposed to study the evolution of the relief in the fluvial-estuarine plain ofthe LRIR, with the aim of understanding how this evolution influenced the genesis of coastalpeatlands in the subtropical region of Brazil, considering the gaps regarding these ecosystemsand their evolution throughout the Quaternary. For this purpose, mapping of themorphosedimentary units will be carried out, the characterization of the deposits,paleoenvironmental reconstruction studies based on OSL and 14C dating, isotopic analysis and,finally, the morphological chemical and physical characterization of the soils. The data obtainedin the field and in the office will be integrated into morphosedimentary mapping, which willalso use remote sensing tools and GIS software. Approximate sedimentation rates over timewill be obtained through age - depth models, derived from dating.