Soils developed from cenozoic material as related to regional physiography in the region in of Jequitai river, MG

Abstract

This study was carried out with the objctive of obtaining information about the relationship between land forms and soils developed from cenozoic materials that occur in the São Francisco river valley and tributaries. The region is located in its Jequitaí, Minas Gerais state, and has a subhumid climate. Soil moisture and temperature regimes are ustic and isothermic, respectivelly. A soil toposequence represented by five pedons was chosen. In the oldest surface from a Terciary material a Typic Haplustox was developed. The other pedons are developed from Holocenic materials deposited by the Sao Francisco river. These are very young soils with argillic horizons, represented by Ultisol and Molisol. Profile 1, a Typic Haplustox, has only resistent minerals in the sand fraction, and kaolinite is the dominant clay mineral. The Plinthic Haplustox (Profile 2) located in a more recent surface has some calcium plagioclases and mica in the sand fraction. Wheathering minerals increase with depth. The other soils, more recent and developed in the youngest surface, are an Oxic Plintaquult (Profile 3), Fluventic Plintustult (Profile 4) and Fluventic Argiustol (profile 5). In these soils the amount of feldspat and micas increase from Pedon 2 to Pedon 5. These minerals are associated with a recent depositional process due to Sao Francisco river work.