Failed rift propagation at lithospheric-scale shear zones and terrane boundaries: implications for Gondwana breakup in the South Atlantic

Abstract

This study investigates how preexisting tectonic structures and crustal strength influence the formation and arrest of rifts, focusing on the Jatobá and Tucano basins in NE Brazil—part of a failed rift system related to the Gondwana breakup. We integrate aeromagnetic and gravity data with structural observations in the Recôncavo-Tucano-Jatobá (RTJ) Rift to better understand this process. Our results show that the RTJ rift propagated northward by reactivating N–S-trending Precambrian structures around 142 Ma, later shifting to E–W propagation along the Ibimirim Fault. This shift was controlled by E–W and ENE–WSW-striking faults that crosscut earlier N–S structures and by the varying strength and orientation of lithotypes across the Pernambuco Shear Zone. The Ibimirim Fault, the master fault of the Jatobá Basin, was influenced by stronger terranes in the west and the shear zone in the east. Geophysical data reveal two crustal blocks with higher density and thickness, suggesting increased rigidity that resisted rift propagation across the shear zone around 121 Ma. These issues associated with the subsequent changes in plate motion altered the stress field, redirecting rifting eastward to the Pernambuco and Paraíba basins (∼100–85 Ma), the final land connection between Africa and South America. This shift led to the activation of the Sergipe-Alagoas–Gabon Rift System. Our findings offer new insights into the tectonic processes driving the breakup of Gondwana.