SOILS WITH FRAGIP AN IN NORTHWESTERN BUENOS AIRES PROVINCE.

Abstract

This paper discusses the morphological, physical, chemical, mineralogical and micromorphological properties of two soil - paleosol sequences. They are located in the NW region (Sandy Pampa) of Buenos Aires province, Argentina. The soils are developed on sandy sandy loess and have lithologic discontinuities, buried soils and fragipans. Two buried paleosoIs with argillic. horizons and an incipient, recently buried soil have been found under the present soil. The older paleosols reflect humid paleoenvironmerital conditions simil to those prevailing at present. The deeper paleosol is a fragipan whose main features are hard or very hard consistence when dry brittleness when moist and the frágments slake when placed in water. Its forrnation has been favoured by a loamy particle-size class, clay and clay-silt bridges, interlocking grains and a moderate calcification process.