Estágio de intemperismo de perfil laterítico em área subtropical com substrato basáltico - superfície aplainada VI (SW PR)

Abstract

Planation surfaces mean the last stage in the reliefs evolution. In order to understand how was the evolution process and formation of the surfaces it becomes necessary to looking for information about the process soil formation related to the climate regime and the bedrock. The Southwest region of Parana and Northwest of Santa Catarina are characterized by a succession of remains of incompletely flattened surfaces, in which one of them stood out for having more than nine meters of weathered material. This study sought to characterize this remaining flat surface by its determining the weathering stage, macro and micromorphological characteristics of the pedon. In addition, there was the possibility of relating the evolution that surface with the etchplanation theory proposed by previous research. Physical analyses were carried as the, granulometry and tipics chemical, micromorphology, clay mineralogy, iron content and analytical chemistry. Therefore, the soil profile presented itself with more than nine meters of material exposed with diffuse transition and moderate A horizon (0 0,20 m), BW1 (0,20 to 1,40 m), Bw2 (1,40 2,50 m), B nític 1 and B nític 2 (2,50 to 8,70 m), BC (8,70 to 9,50 m) and CB (from 9,50 m). Through the microstructure it was observed the vertical transformation of the B horizon latosolic from nític B horizon. In the stage of weathering, mineralogical analysis, chemical and iron content have revealed that the soil profile studied is evolving to an advanced stage, in other words, from ferruginous to ferralitic. Such analysis, especially mineral, allowed to define the partial hydrolysis as the main process related to the formation and evolution of the soil. In this, there is a predominance of kaolinite (1:1), characterized by partial loss of silica (monossialitization) and by the vertical movement of materials. Therefore, we can confirm evolutionary compatibility with etchplanation theory. The occurrence of chemical weathering was possible due to weather conditions and rocky soil, basalt, promoting the vertical movement of materials, causing isovolumetric loss and thus the planation.