Salt-magma interactions influence intrusion distribution and salt tectonics in the Santos Basin, offshore Brazil

Magee, Craig; Pichel, Leonardo Muniz; Madden-Nadeau, Amber; Jackson, Christopher; Mohriak, Webster Ueipass

doi:10.31223/x52g64

Cited by 3 publications

(3 citation statements)

References 64 publications

(133 reference statements)

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“…Along the proximal margin of the Santos Basin, potential field data indicate a zone of en echelon Moho uplifts (Meisling et al., 2001) and crustal thinning, along with extensive seaward‐dipping reflector sequences (SDRs) indicating accommodation space formation related to crustal extension during a magma‐rich rift phase. A faulted base salt surface in the inner, western part of the Santos Basin and isolated graben structures such as the Merluza Graben area in the northern part of the basin (Magee et al., 2021), indicate that the Avedis ridge has been active at least until deposition of the extensive early Aptian‐aged evaporite layer in the central South Atlantic. Toward the NE basin margin, this zone merges with the Cabo Frio‐Benguela transform (Guiraud et al., 2010; Mohriak et al., 1995), which laterally offsets the rift axis by about 500 km eastwards into the northerly adjoining Campos‐Kwanza/Benguela rift segment.…”

Section: Comparison Of Numerical Models To Two Natural Microplate Settingsmentioning

confidence: 99%

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Neuharth

Brune

Glerum

et al. 2021

Geochem Geophys Geosyst

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Continental microplates are enigmatic plate boundary features, which can occur in extensional and compressional regimes. Here we focus on microplate formation and their temporal evolution in continental rift settings. To this aim, we employ the geodynamic finite element software ASPECT to conduct 3D lithospheric‐scale numerical models from rift inception to continental breakup. We find that depending on the strike‐perpendicular offset and crustal strength, rift segments connect or interact through one of four regimes: (1) an oblique rift, (2) a transform fault, (3) a rotating continental microplate or (4) a rift jump. We highlight that rotating microplates form at offsets >200 km in weak to moderately strong crustal setups. We describe the dynamics of microplate evolution from initial rift propagation, to segment overlap, vertical‐axis rotation, and eventually continental breakup. These models may explain microplate size and kinematics of the Flemish Cap, the Sao Paulo Plateau, and other continental microplates that formed during continental rifting worldwide.

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Section: Comparison Of Numerical Models To Two Natural Microplate Settingsmentioning

confidence: 99%

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Neuharth

Brune

Glerum

et al. 2021

Geochem Geophys Geosyst

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“…2). This complex rift propagation resulted in various syn-to post-rift intrusive and volcanic features in the southwestern Santos Basin, in the Abimael Ridge (Mohriak et al, 2008; and northwards around the Merluza Graben (Magee et al, 2020). It also produced an anonymously thick syn-rift and the hydrocarbon-rich, pre-salt sag succession above stretched continental crust on the São Paulo Plateau to the east (Gomes et al, 2009;Scotchman et al, 2006;.…”

Section: Geological Settingmentioning

confidence: 99%

“…In comparison with other areas of the Santos Basin, the Merluza Graben has been relatively under-studied (cf. Mohriak et al 2010;Rowan et al, 2019;Magee et al, 2020). However, it represents an important setting in which to understand the interplay between diachronous rifting, and salt deposition and deformation, not only in the Santos Basin, but in other hyper-extended rifted margins worldwide.…”

Section: Introductionmentioning

confidence: 99%

The Merluza Graben: how a failed spreading centre influenced margin structure, salt deposition and tectonics in the Santos Basin, Brazil

Pichel¹,

Jackson²,

Peel³

et al. 2021

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The relative timing between crustal extension and salt deposition can vary spatially along passive margin salt basins as continents unzip or the locus of extension shifts through time towards the embryonic spreading centre. Determining the relative timing of salt deposition, rifting and seafloor spreading is often problematic due to the diachronous nature of rifting, the ability of salt fill pre-existing topography and to the post-rift gravity-driven salt tectonics. We use 2D PSDM seismic data and structural restorations to investigate the Merluza Graben, a large rift-related depocentre located at the proximal and southernmost portion of the Santos Basin, Brazil and at the continuation of a failed spreading centre, the Abimael Ridge. The graben presents up to 3.5 km of base-salt relief at its basinward-bounding fault and internal base-salt horsts up to 1 km high. This compartmentalises deformation, producing extensional and contraction salt structures, ramp-syncline basins and expulsion rollovers within the graben, resulting in a remarkably different and variable style of salt tectonics than in the adjacent areas. We also conduct structural restorations to analyse the spatial and temporal evolution of this complex style of deformation and potential prolonged crustal extension in the Merluza Graben by using discrepancies in the present and restored salt area. This approach affords further constraints on local variations in the relative timing of rifting and salt deposition and its impact on salt tectonics along the margin, which can be applied to other hyper-extended rifted margins worldwide.

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The Merluza Graben: How a Failed Spreading Center Influenced Margin Structure, and Salt Deposition and Tectonics in the Santos Basin, Brazil

et al. 2021

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In many of these basins, the timing of salt deposition varies laterally from syn-rift (i.e., during the bulk of crustal extension) to post-rift (i.e., after the bulk of crustal extension ceased); this diachroneity can occur as the timing of rifting and break-up varies along-strike as continents "unzip" (cf., Northern and Southern Red Sea, Augustin et al., 2014;Rowan, 2014), or as the locus of rift-related extension shifts basinward toward the embryonic spreading center. In the latter case, salt deposited in proximal areas after crustal faulting had ceased would be called "post-rift", whereas age-equivalent salt deposited in more distal areas during ongoing crustal faulting and extension would be defined as syn-rift (e.g., the South and Central Atlantic salt basins; Rowan, 2014Rowan, , 2020Tari et al., 2017).Because of the diachroneity in tectonics and deposition, it can be difficult to determine the relative timing of salt deposition, rift-related fault activity, and seafloor spreading (

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Salt-magma interactions influence intrusion distribution and salt tectonics in the Santos Basin, offshore Brazil

Abstract: The seismic reflection data that support the findings of this study are available from ANP but restrictions apply to the availability of these data, which were used under a confidentiality agreement for the current study, and so are not publicly available.

Cited by 3 publications

References 64 publications

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

The Merluza Graben: how a failed spreading centre influenced margin structure, salt deposition and tectonics in the Santos Basin, Brazil

The Merluza Graben: How a Failed Spreading Center Influenced Margin Structure, and Salt Deposition and Tectonics in the Santos Basin, Brazil

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