Morphostructural influence and neotectonic activity in the geomorphological configuration of southeast Paraíba and northeast Pernambuco, Brazil

Abstract

The current study provides critical insights into the field of geomorphology by examining the impact of lithological structures and tectonic activities on the geomorphological configuration of terrain and drainage networks in the southeast of Paraíba and northeast of Pernambuco, Brazil. This geographical region is characterized by phenomena of uplift and fluvial incision at various sites, yet remains inadequately explored with respect to its active deformation and the broader context of its recent geology. Therefore, the primary aim of this research is to elucidate the morphostructural and neotectonic influences on the geomorphological formations in these sectors of Brazil. The methodology encompasses morphostructural analysis, leveraging data derived from altimetry, slope, and geomorphology maps, categorized into taxonomic terrain units. Additionally, this research incorporates the use of morphometric indices, including the Stream Length-Gradient Index (SL), Valley Floor Width (VF), and Asymmetry Factor (AF) to quantify geomorphological anomalies. The analysis of the SL index indicates that a significant portion (87.5 %) of the drainage network exhibits anomalies. Furthermore, the VF index results reveal that 66 % of the profiles analyzed manifest anomalies of various magnitudes. Within the study region, the AF index elucidates the distribution of sub-basins into categories of low (0−30), medium (31−50), and high (>51) asymmetry, comprising 25 %, 31 %, and 44 % of the sub-basins, respectively. The sub-basins demonstrate channel disequilibrium, as evidenced by the SL index, attributed to numerous transient knickpoints along the drainage profiles. This observation is consistent with previous findings in the Koyna-Warna Shallow Seismic Region. The study's outcomes reveal both qualitatively and quantitatively anomalous patterns in the drainage network and terrain forms, which are likely indicative of recent tectonic events affecting the entire eastern edge of Northeast Brazil. Consequently, the findings highlight the significant role of post-Miocene tectonic events in shaping the relief of the study area.

Keywords

• Geomorphic indices
• Geomorphological mapping
• Lithological structures
• Morphometry
• Tectonic geomorphology