Evidence of soils and paleosols in the Poznań Formation (Neogene, Polish Lowland)

Abstract

A succession of stacked paleosol profiles was recognized in open pits in the western Wielkopolska region (Poland). Field observations and micromorphological studies made it possible to distinguish the following pedostructures, formed in contrasting environments: soil horizons, crystallaria, concretions, redoximorphic structures, Fe-Mn globulae and slickensides. In both soils (Holocene) and paleosols (Pleistocene or/and Pliocene?), surface horizons are present (horizon A), marked by rhizocretions. There are two separate carbonate soils. One of them contains calcite concretions and gypsum pedofeatures, presumably formed in arid or semi-arid conditions. Two of the soil profiles are probably truncated, and only subsurface horizons are present (horizon B). In some cases, paleosols are separated by sediment layers slightly influenced by pedogenesis (horizon BC). Carbonate soils (Bk) indicate water deficit during their formation. The presence of horizons with slickensides (Bss) indicates intervals with contrasting seasonal climates (wet and dry cycles). The profiles were influenced by gleying processes which caused redistribution of iron oxides and formation of iron and iron-manganese concretions. The pedostructures recognised reflect different climatic conditions as well as humidity changes during the time of their formation.