Gilgai Microrelief Morphology in the Caicó – Rn Region

Abstract

The Gilgai microrelief is characterized as a succession of alternating micromounds and depressions, in soils rich in expansive clays (2:1). Its genesis is related to successive cycles of wetting and drying, especially pronounced under conditions of imperfectly or poorly drained soils. There are still many gaps in the literature on the genesis, evolution and dynamics of the processes involved in areas with Gilgais in Brazil, so studies aimed at understanding their patterns of occurrence are necessary. Thus, the aim of this study is a morphological characterization of Gilgais, in the Potiguar semi-arid region, to verify the hypothesis of homogeneity of its patterns of regional occurrence. The analyzed data refer to two sampling sites, where a total of 120 micro-reliefs were measured, in relation to their height, width and distance between micromounds. Descriptive statistical analysis and ANOVA analysis of variance were applied to the data, seeking to understand the patterns of occurrence of microreliefs. The Gilgai microreliefs observed in the two sampling sites present morphological patterns specific to each site, and differ in some aspects. In both places studied, the micro-reliefs were classified as isometric shapes with no defined orientation. However, in terms of height, width and distance between micromounds, the two sampling sites present statistically significant differences, demonstrated through the analysis of variance of the ANOVA statistical test. This indicates that despite having similar shapes, the size proportions and spacing patterns of the micro-reliefs found in each location are different, ruling out the hypothesis of homogeneous patterns of regional occurrence.