GÊNESE E MICROPEDOLOGIA DE SOLOS DO MÉDIO JEQUITINHONHA, DE TURMALINA A PEDRA AZUL, MG

Abstract

The pedogenesis and micropedology of seven selected soils from the mid-Jequitinhonha Valley werecharacterized, aiming to identify properties associated with the distribution of soils in the landscape. Podzolswere found on the top of the upper planation surface, closely associated with quartzite and its weatheringproducts. In the bottom of the tectonic depression which forms the mid-valley, soils with low cation exchangecapacity (CEC), low clay activity and presence of stony pavement are found, suggesting a change frompast, humid climate to present-day semi-arid climate. Kaolinitic soils with low Fe-oxides content undersuch regime are thought to represent relicts of former humid climates, being correlatable to the typicalYellow Latosols from the coastal tablelands (tabuleiros). In the ill-drained Quaternary plains, soils withhigher sodium contents are found, indicating the imperfect leaching under the present climatic condition.On the top of the regional, late Tertiary surface, deep Latosols occur, associated with saprolites of variouslithologies and Tertiary sediments derived from the erosion of these paleoweathering profiles. In all soils,some micropedological features confirm the polygenetic nature of the soils and landscape of the mid-Jequitinhonha, where either morphogenesis or pedogenesis have dominated, depending on climate,lithological control and tectonic activity .