ANÁLISE DA RELAÇÃO ENTRE SISMICIDADE E OS LINEAMENTOS ESTRUTURAIS DA BACIA SEDIMENTAR DO PANTANAL NO CENTRO-OESTE DO BRASIL

Abstract

The Pantanal Sedimentary Basin (PSB), located inside the South American Plate, presents a geodynamic evolution marked by the interaction of two tectonic regimes: the strike-slip regime associated with the Transbrazilian Lineament and the compressive regime resulting from the collision of the Nazca Plate with the South American Plate. The combined action of these regimes resulted in a complex neotectonic setting that directly influenced the morphology, drainage network and seismicity of the region. The analysis of the structural lineaments highlighted predominant directions N-S, NE-SW and E-W, with emphasis to Paraguay, Taquari and Negro rivers, in addition to Maracaju-Campo Grande Plateau. The seismic data (1990-2023) has revealed 43 events with magnitudes ranging from 2,5 to 4,8 Mb, with predominance of low magnitude seisms. The distribution of these events indicates strong structural control exercised by normal faults and oblique transcurrences that limit crustal blocks and conditionate subsidence and lifting areas in addition to associated deformations. The PSB is characterized as an asymmetric depression of half graben type, leaned towards east and presenting morphotectonics features such as cliffs, hanging valley, fluvial elbows, avulsion zones and lacustrine formations. The continuous presence of seismic activity confirms the active character of the region's tectonics, making PSB an important example of a basin affected by neotectonic processes and resurgence of ancient structures. The correlation between the structural discontinuities represented by relief drainage and seismicity in the PSB, most of the time, doesn’t exist in a direct way, such as those seismic beams in direction N-S in the center of the Basin.