Landscape evolution of the Torres Trough, Paraná Basin, southern Brazil, based on morphostructural analysis

Abstract

The upper Paraná Basin units of the Serra Geral Group comprise the aeolian sandstones of the Botucatu Formation and overlying lava flows. Since distinct altitudes of the boundary between these units are observed (from 0 m up to 1200 m m.s.l), referred to as the Botucatu aeolian sandstones-lava flow boundary (BLB), it is as a key reference surface for identifying and quantifying major vertical faults and relative displacements across these faults. To map and model these displacements, integrated data from stratigraphic wells, fieldwork in key areas and remote sensing image analysis were utilized. Block displacements were observed in SSW-NNE profiles along the Southern escarpment, where the contact surface boundary ranges from sea level in the South to over 1200 m to the Northwest, indicating a progressively increasing elevation of the BLB towards the North. This trend is also evident in the ESE-WNW cross-section on the Serra Geral Plateau, where the BLB varies in stratigraphic well data from −534 m to 691 m from SW to NE. Additionally, the altitudes of the boundary between the Paraná Basin and the basement rocks (Basin-Basement Boundary − BBB) were analyzed, revealing the lowest points in a stratigraphic well in the NW (−3000 m) near the Torres Trough and the highest points in the NE (400 m). The significant altitude variations at both boundaries are constrained by the main lineaments observed in the area defining horst and graben domains. Notably, the Torres Trough, also referred to as the Torres Syncline, is identified as a structural low trending SE-NW. This suggests that the SE borders of the basin form part of the flanks of the Cretaceous rift, while the NE region represents a prominently uplifted block. The integration of lineaments delineates an extensive horst and graben system that developed post-Gondwana breakup, configuring four main domains based on the BLB altitudes: Torres, RS (−120 to 150 m), Timbé do Sul (200 to 500 m), Serra do Rio do Rastro (600 to 900 m), and Urubici, SC (1000–1300 m). Phanerozoic and later Cenozoic tectonic activity significantly altered the configuration of the Paraná Basin, through major block tilting and faulting, particularly along the escarpments.