WITHDRAWN: 3D crustal architecture of a magma-poor passive margin, Santos, Campos and Espírito Santo Basins – Comparisons with a volcanic passive margin, Pelotas Basin – Offshore Brazil

Zalán, Pedro Víctor; Severino, Maria do Carmo Garcia; Rigoti, Caesar Augusto; Magnavita, Luciano P.; Oliveira, João Alberto Bach de; Viana, Adriano R.

doi:10.1016/j.marpetgeo.2012.08.011

Cited by 10 publications

(26 citation statements)

References 40 publications

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“…In some cases, extension proceeded far enough in the failed rifts separating continental fragments from the interior that exhumed and serpentinized mantle directly underlies the basin sediments. Exhumed mantle is inferred from seismic and potential field studies for the Porcupine Basin (Kimbell et al, 2010), Phu Khanh Basin (Savva et al, 2013), and the Santos Basin (Zalán et al, 2011). Microcontinents, such as Jan Mayen and the Seychelles, are surrounded by oceanic crust.…”

Section: Continental Fragments and Microcontinents: General Settingmentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

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Abstract. Allochthonous accreted terranes are exotic geologic units that originated from anomalous crustal regions on a subducting oceanic plate and were transferred to the overriding plate by accretionary processes during subduction. The geographical regions that eventually become accreted allochthonous terranes include island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents. These future allochthonous terranes (FATs) contribute to continental crustal growth, subduction dynamics, and crustal recycling in the mantle. We present a review of modern FATs and their accreted counterparts based on available geological, seismic, and gravity studies and discuss their crustal structure, geological origin, and bulk crustal density. Island arcs have an average crustal thickness of 26 km, average bulk crustal density of 2.79 g cm −3 , and three distinct crustal units overlying a crust-mantle transition zone. Oceanic plateaus and submarine ridges have an average crustal thickness of 21 km and average bulk crustal density of 2.84 g cm −3 . Continental fragments presently on the ocean floor have an average crustal thickness of 25 km and bulk crustal density of 2.81 g cm −3 . Accreted allochthonous terranes can be compared to these crustal compilations to better understand which units of crust are accreted or subducted. In general, most accreted terranes are thin crustal units sheared off of FATs and added onto the accretionary prism, with thicknesses on the order of hundreds of meters to a few kilometers. However, many island arcs, oceanic plateaus, and submarine ridges were sheared off in the subduction interface and underplated onto the overlying continent. Other times we find evidence of terrane-continent collision leaving behind accreted terranes 25-40 km thick. We posit that rheologically weak crustal layers or shear zones that were formed when the FATs were produced can be activated as detachments during subduction, allowing parts of the FAT crust to accrete and others to subduct. In many modern FATs on the ocean floor, a sub-crustal layer of high seismic velocities, interpreted as ultramafic material, could serve as a detachment or delaminate during subduction.

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Section: Continental Fragments and Microcontinents: General Settingmentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

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Section: Discussionmentioning

confidence: 96%

“…The central and southern segments in the South Atlantic are both very wide (>300 km) with highly extended crust, but they exhibit distinctly different magmatic activity (Blaich et al., 2013; Contrucci et al., 2004; Moulin et al., 2005; Figures 1c and 1d). While the central South Atlantic is considered to be magma‐poor (Blaich et al., 2011; Péron‐Pinvidic et al., 2015; Rowan, 2014; Unternehr et al., 2010; Zalán et al., 2011), the margins of the southern segment of the South Atlantic conjugate margins are characterized by significant volcanic addition (Blaich et al., 2013; Franke, 2013; Paton et al., 2017). The central South Atlantic segment is characterized by the presence of a thick (1–2 km) Aptian salt layer along both the Brazilian and West African margins (Karner & Gambôa, 2007; Mohriak et al., 2008).…”

Section: Discussionmentioning

confidence: 99%

“…However, the nature of the most distal margin is less constrained and highly debated. Earlier studies have suggested the occurrence of exhumed mantle (Rowan, 2014;Unternehr et al, 2010;Zalán et al, 2011). In contrast, Cowie et al (2017) suggest that the distal Aptian salt is underlain by hyper-extended continental crust rather than exhumed mantle.…”

Section: Comparison To Natural Systemsmentioning

confidence: 96%

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Magmatism at Passive Margins: Effects of Depth‐Dependent Wide Rifting and Lithospheric Counterflow

Lü

Huismans

2022

JGR Solid Earth

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Rifted passive margins exhibit a large variety in the timing, distribution, and amount of magmatism. The factors controlling magmatism during rifted margin formation, remain, however, incompletely understood, partly owing to the complex rifting styles. In this study, we use 2‐Dimensional numerical models to investigate the effects of depth‐dependent wide rifting and lithospheric counterflow on magmatism during rifted margin formation. Results show that a strong crust promotes narrow margins with a sharp transition to normal thickness oceanic crust whereas a weak crust promotes depth‐dependent wide rifting, with preferential removal of mantle lithosphere, leading to formation of wide margins with over‐thickened (>18 km) igneous crust in the distal margin. Counterflow of depleted lithospheric mantle, in contrast, may delay syn‐rift magmatism, and result in exhumed a‐magmatic continental mantle at narrow margins. The combination of wide rifting and lithospheric counterflow results in magma‐poor wide margins, with in some cases a transition to excess magmatic activity at breakup. Our models provide an explanation for the contrasting magmatic productivity at narrow and wide rifted margins, such as observed in the Lofoten‐Vesterålen, Newfoundland, Kwanza Basin, and Orange Basin margins.

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“…[2011]), and (c) Campos Basin, Brazil (adapted from Zalán et al. [2011]), (d) Southern Red Sea (adapted from Mohriak and Leroy [2013]) and (e) southern Nova Scotia, Canada (adapted from Goteti et al. [2013]).…”

Section: Introductionmentioning

confidence: 99%

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

et al. 2022

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Continental rifting and breakup are a product of the extension and thinning of the lithosphere and ocean floor spreading (McKenzie, 1978). The style of rifting and margin architecture is generally controlled by the rheology and overall composition of the crust and mantle lithosphere. Strong crust favors narrow rifting whereas weak crust promotes formation of wide rifted margins (Buck, 1991;Huismans & Beaumont, 2011. Other factors such as the lithospheric thermal state and thickness, inheritance and temporal and spatial variations in rifting kinematics also influence rifted margin architecture (

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WITHDRAWN: 3D crustal architecture of a magma-poor passive margin, Santos, Campos and Espírito Santo Basins – Comparisons with a volcanic passive margin, Pelotas Basin – Offshore Brazil

Cited by 10 publications

References 40 publications

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Magmatism at Passive Margins: Effects of Depth‐Dependent Wide Rifting and Lithospheric Counterflow

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

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