Composição mineralogica da fração grosseira em dois perfis de solo do município de Lavras - MG

Abstract

This study was conducted to identify the coarse fraction, the present material, determinate the grade of the roundness of quartz grains and verify the presence of lithological descontinuity in two soil profiles: Dusky Red Latosol (profile 1) and Red-Yellow Podzolic (profile 2) occurring in Lavras, State of Minas Gerais. For that profiles samples were under the common work methods used in studies of that kind. The results obtained led to the following conclusions: 1) the heavy fraction of the two profiles studied has simple mineralogical composition that is basically formed by stable minerais: zirconite, turmaline, rutile, staurolite and opaques which are the dominants; 2) the parent material of the soils studied was derived from igneous basic and acid rocks with contributions of rocks with high degree of metamorphism; 3) the results of roundness obtained for quartz grains were 0,24 and 0,28 for profile 1 and profile 2 that permitted us to classify them as sub-angular and sub-rounded respectively; 4) the profile 2 presents in the A2 horizon a lithological descontinuity whithout association to stone lines.