The crystalline shield rocks that outcrop in the central-east and north-east of the state of Santa Catarina lie in a strong and wavy relief characterizing the northern Santa Catarina Coastal Mountains. The irregular surface results from the magmatic metamorphic cycles of the crust, responsible for the reworking of ancient rocks formed from the Archean to the Proterozoic. This compartment consists of metamorphic rocks while information about genesis and mineralogical composition of the soils derived from it are scarce, motivating this study. Five profiles resulting from pedogenesis of these materials were investigated. The first profile (P1), developed from hornblendites from the Granulitic Complex of Santa Catarina, was described at the top of Pomerode, in a strong and wavy relief. The second and fifth profiles (P2 and P5), both developed from mafic granulites of the same complex, in Massaranduba and Blumenau, respectively, were described at the base of the slope, in a wavy local relief; the third soil profile (P3), derived from micachist of Brusque Metamorphic Complex, was described on the slope of the strong and wavy relief near Botuverá. The fourth profile (P4) resulted from a granitoid pedogenesis of Faxinal Granitic-Gneissic formation. This profile was described in the lower third of the slope in a wavy relief. In these soils, general and morphological descriptions of soils and underlying lithology were made, as well as physical and chemical analyses of characterization and mineralogical analyses of the silt and clay fraction by X-ray diffraction (XRD), to evaluate the transformations undergone by the minerals in rocks during the soil evolution. The textural contrast was high in all soils, or block structure development associated with the presence of clay skins, consistent with the definition of a diagnostic B horizon in the Brazilian Soil Classification System (similar to the argilic horizon in the USDA Soil Taxonomy System), low activity clay, and dystrophic character, which allowed its classification as Dystrophic Yellow Argisol (P1), Alitic Yellow Argisols (P2, P3 and P5) and Aluminic Red Yellow Argisol (P4) in the Brazilian System of Soil Classification, version 2006, and Ultisols in the USDA Soil Taxonomy System. In all Ultisols, kaolinite was dominant, followed by illite, interstratified illite-vermiculite and/or vermiculite with polymers of hydroxy-Al interlayers. The formation of kaolinite is the result of the dissolution of primary minerals favored by the humid subtropical climate conditions. The 2:1 clay minerals found in the soils probably result from phyllosilicate transformation. The increase in the activity of the clay fraction was related to the increase in the amount of 2:1 clay minerals that was higher in the Ultisol developed from Granada-Muscovite-Schist (P3).
Ultisols; clay mineralogy; metamorphic rocks; chemical properties
