High-resolution Seismic imaging in the Santos Basin, Brazil and its impact on Salt Mechanics

Abstract

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Deep Structure of the Santos Basin, Offshore Brazil From 3D Inversion of magnetotelluric Data

“…Many authors propose an extension‐driven model in which the Albian Gap (AG) (and overlying rollover) formed due to post‐Albian gravity‐driven extension accommodated by slip on a large, counter‐regional, salt‐detached listric normal fault, the Cabo Frio Fault (CFF, e.g., Cobbold & Szatmari, 1991; Davison et al., 2012; Demercian et al., 1993; Guerra & Underhill, 2012; Mohriak et al., 1995; Rowan & Ratcliff, 2012; Rowan et al., 2022). Others propose an expulsion‐driven model in which the AG was established earlier, during the Albian and post‐Albian, with the post‐Albian deformation controlled by differential loading, vertical subsidence, and basinward salt expulsion in the absence of significant lateral extension (Ge et al., 1997; Gemmer et al., 2005; Jackson et al., 2015; Krezcek et al., 2007; Lebit et al., 2019; Szatmari et al., 1996). Recently, Pichel and Jackson (2020) showed that the geometry and kinematics of the AG vary along‐strike and propose that both post‐Albian extension and expulsion play a significant role in its evolution.…”

“…The seismic reflection data utilized in much of these studies mostly did not penetrate below 14 km depth and hence the deep crustal structure of the predominantly counterregional normal Cabo Frio Faults (CFF) against which the AG terminates -is not fully understood. Based on highresolution enhanced seismic imaging of salt and pre-salt sections and well data analysis, Lebit et al (2019) found little or no indication of lateral movement along the base of the Aptian layered evaporite sequence or evidence for a distinguished detachment fault as suggested by common models accounting for the genesis of the AG (e.g., Cobbold & Szatmari, 1991;Davison et al, 2012;Demercian et al, 1993;Guerra & Underhill, 2012;Mohriak et al, 1995;Rowan & Ratcliff, 2012). It may therefore be instructive to investigate the structure of the proposed CFF zone (Figures 1 and 2) at depth using a non-seismic deep imaging method like magnetotellurics.…”