Mineralogia da fracao grosseira de latossolos sob cerrado do município de Rio Paranaiba - MG

Abstract

Two soils profiles at Rio Paranaiba county, State of Minas Gerais were studied in order to evaluate the mineralogical composition of the coarse fraction and identify parent material, degree of roundness of quartz grains and also to verify the possible ocurrence of lithological discontinuiUes. Profile P1 is a Latossolo Vermelho Amarelo and Profile P2 is a Latossolo Roxo. The subfraction fine sand was aplited in light and heavy minerais, being the last ones classifeed in magnetic and non-magnetic ones. The light fraction was used to determine the degree of roundness of quartz grains and in the non-magnetic heavy fractions was identified and counted transparent minerais in order- to evaluate soils parent material. The uniformity of the soils was evaluated by means of the indexes fine sand/coarse sand, very fine sand/coarse sand, zirconite/ tourmaline and zirconita/(tourmaline + rutile). The mineralogical composition is simple, formed by stable minerais which are derived from clsyey sedimente and basic rocks with mixture of acidic rocks. It was also observed the ocurrence of lithological discontinuity at 102-200 cm depth, in the Utossolo Roxo, without association with stone lines.