Lithospheric structuration onshore-offshore of the Sergipe-Alagoas passive margin, NE Brazil, based on wide-angle seismic data

Abstract

The structure and nature of the crust underlying the Camamu-Almada-Jequitinhonha-Sergipe-Alagoas basins System, in the NE Brazilian margin, were investigated based on the interpretation of 12 wide-Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. angle seismic profiles acquired during the SALSA (Sergipe ALagoas Seismic Acquisition) experiment in 2014. In this work, we present two 220-km-long NW-SE combined wide-angle and reflection seismic profiles, SL 01 and SL 02, that have been acquired using 15 ocean-bottom-seismometers along each profile, offshore the southern part of the Sergipe Alagoas Basin (SAB), north of the Vaza-Barris Transfer zone. The SL 02 has a 150-km long inland continuation with 20 land-seismic-stations until the Sergipano Fold Belt (SFB). Wide-angle seismic forward modeling allows us to precisely divide the crust in three domains: beneath the continental shelf, a ∼100 km wide necking zone is imaged where the continental crust thins from ∼35 km on the Unthinned Continental Domain, which displays a threelayered crust structure, to less than 8 km on the Oceanic Crust Domain. In the necking zone, the upper and the middle layers thin dramatically and almost disappear, while the Moho discontinuity shows clear PmPs. The Continental-Oceanic Crust Boundary (COB) is located at ∼80 km from the coastline and is marked by intracrustal seismic reflectors and changes in the seismic velocity, showing a sharp transition. On profile SL02, the oceanic crust is perturbed by a volcanic edifice together with an anomalous velocity zone underneath the area. Highlights ► Sergipe Alagoas Basin passive margin modeling. ► Wide-angle refraction seismic integrated with Multi-Channel reflection seismic data. ► Location of the Continental-Oceanic crust boundary. ► Lithospheric structuration and segmentation of Brazil's margin in Central Atlantic.

Joint inversion of receiver functions and surface wave dispersion in the Recôncavo–Tucano basin of NE Brazil: implications for basin formation

“…Recall that syn-rift magmatism was contemplated by Mohriak et al (2000), as they observed thick wedges of seaward dipping reflectors on seismic profiles crossing the Sergipe-Alagoas basin. Also, recent investigations of this basin by onshore-offshore seismic refraction have found anomalously fast lower continental crust P-velocity in the necking zone (Pinheiro et al 2018), which gives further support to the occurrence of syn-rift magmatism. Another hypothesis for the fast-velocity layer under the RTJ rift basins could therefore be that syn-rift magmatic intrusions were responsible for its formation.…”

“…The closest intrusions consist of three subparallel dolerite dykes East of the Tucano basin, with K-Ar dates of 105 ± 9 Ma, which were inferred indirectly from aeromagnetic and outcrop data (Magnavita et al 1994). Rift-related magmatism seems to be restricted to breakup along the associated marginal basins, where it has been identified as either fast-velocity (>7.0 km s -1 ) lowermost crustal bodies in refraction lines or small-volume, on-shore mafic intrusives (Blaich et al 2008;Pinheiro et al 2018).…”

The Tectonic Structure and Evolution of the Potiguar‐Ceará Rifted Margin of Brazil

“…The graben and configuration of dikes (Figure 1), which is roughly parallel to the opening direction, and complex strata geometry with some folding, may indicate that the deformation in this segment of Potiguar involved strike‐slip to oblique tectonic component in the early rift phase. The amount of extension recorded in the grabens is comparatively minor and the average crust thickness of the segment currently above sea level is ∼35 km (Assumpção et al., 2013; Schnürle et al., 2023), that is, somewhat thicker than offshore under the shelf (Aslanian et al., 2021; Pinheiro et al., 2018). The relatively thin lithosphere is the region (Barbosa et al., 2023) may have caused that the shallow Potiguar basin is currently above sea level.…”

Meta‐analysis of the long‐term stratigraphic evolution of rifted margin basins: The GeoDyNamical Analysis approach applied to the South Atlantic Ocean

“…In contrast, the rifted margins of the Central Segment (Figure 1) are wide (up to 600 km; Clerc et al, 2018; Contrucci et al, 2004; de Matos et al, 2021; Evain et al, 2015; Mohriak, Nemčok, et al, 2008; Moulin, 2003; Moulin et al, 2005; Péron‐Pinvidic et al, 2013, 2017; Pinheiro et al, 2018; Unternehr et al, 2010; Figure 2b). Their crustal necking domains are associated with wide distal hyperextended domains and ductilely deformed lower crust (“weak or hot margin type”; e.g.…”