Influence of tectonic regime superposition on damage zone structures in a basin-boundary fault, Jatobá basin, NE Brazil

Abstract

We integrated magnetic, gravity, and structural data to investigate the Ibimirim Fault and the evolution of its damage zones within the Jatobá Basin, NE Brazil. Our findings indicate that the magnetic anomalies observed within the Pernambuco and Cruzeiro do Nordeste shear zones are consistent with the strike of the Ibimirim Fault in the study area. Integrated with structural analysis of the Precambrian fabric and rift fault, we suggest that the basement fabric influences the position and geometry of the Ibimirim Fault. Gravity inversion revealed that the Jatobá Basin contains three depocenters, with the main one situated in the central part of the Ibimirim Fault. A fault throw analysis indicates that the Ibimirim Fault comprises three main fault segments, with this study focusing on the area where the central and eastern segments connect. In this overstep area, extensional and compressional fault sets occur in the fault damage zone. The compressional structures crosscut and displace the extensional older structures. The superposition of these structures enhances structural fracturing connectivity without increasing the damage zone width. Paleostress characterization shows extensional structures with sub-vertical σ1 and sub-horizontal σ3 (05/061). In contrast, compressional structures have sub-vertical σ3 and sub-horizontal σ1 (03/349), indicating a non-colinear basin inversion likely driven by far-field stresses from the Andes and the Mid-Atlantic Ridge. This research highlights the intricate interplay between tectonic regime superposition and the evolution of extensional and compressional structures within the same fault damage zone, with significant implications for understanding the formation of sub seismic structures in these regions.