Influence of magma-poor versus magma-rich passive margins on subduction initiation

Auzemery, Antoine; Yamato, Philippe; Duretz, Thibault; Willingshofer, Ernst; Maţenco, Liviu; Porkoláb, Kristóf

doi:10.1016/j.gr.2021.11.012

Cited by 7 publications

(5 citation statements)

References 87 publications

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“…These consist of the pre-orogenic rifted margin architecture and the location of the décollement level. Note that in the initial templates of both models (Figures 4a and 5a) a short slab is simulated in the mantle to facilitate subduction initiation in the distal oceanic crust, consistent with Tan (2020) and Auzemery et al (2022).…”

Section: Input Data and Modelling Setupsupporting

confidence: 70%

“…Sutra et al, 2013) (Figure 1b). A recent study, using a numerical modelling approach, reported how magma-rich rifted margins interact with the onset of subduction and suggested that subduction initiates within the oceanic lithosphere (Auzemery et al, 2022). Nevertheless, still many questions remain, such as, how do inverted magma-rich rifted margins evolve during a more mature collisional stage and lead to the formation of orogens?…”

Section: Introductionmentioning

confidence: 99%

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Inverted Magma-rich Versus Magma-poor Rifted Margins: Implications for Early Orogenic Systems

Gómez-Romeu

Jammes

Ducoux

et al. 2023

tekt

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Mountain belts are often the result of former inverted rifts or rifted margins. Up to date, relics of magma-poor rifted margins have been found in orogens allowing the investigation of how these margins reactivate and control the formation of mountain belts. In contrast, magma-rich rifted margins have barely been recognized within orogenic systems, and consequently how these margins reactivate and control subsequent orogenesis is poorly understood. We use a thermo-mechanical model to investigate the mechanical behaviour of reactivated magma-rich versus magma-poor rifted margins during early orogenesis (i.e. margin inversion). Input data for our modelling experiments are obtained from two natural laboratories. One is the Demerara Plateau characterized by a mildly shortened magma-rich rifted margin. Its décollement level is observed at the top of the syn-kinematic volcanics, which propagates downwards into a frozen incipient subduction. The other study-case is the Basque-Cantabrian Belt consisting of a reactivated magma-poor hyper-extended rift system with the décollement level at the bottom of the syn-rift sediments. Our modelling results, for inverted magma-rich rifted margin, show that the syn-kinematic volcanics undergo subduction as they are mechanically coupled with the underlying rifted lithosphere. Hence, only post-rift sediments are accreted within the early orogenic accretionary wedge. In contrast, both the syn- and post-rift sediments from a reactivated magma-poor rifted margin are expected to be preserved within the accretionary wedge. Therefore, we conclude that the presence or absence of syn-rift sediments within an accretionary prism may represent a robust indicator to determine the nature of reactivated rifted margins within orogens. We believe that our results may strongly contribute to recognize, the so far poorly identified, magma-rich rifted margins within present-day orogenic systems.

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Section: Input Data and Modelling Setupsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Inverted Magma-rich Versus Magma-poor Rifted Margins: Implications for Early Orogenic Systems

Gómez-Romeu

Jammes

Ducoux

et al. 2023

tekt

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“…Such an embryonic basin-margin system is likely to be more laterally homogeneous than ocean basins, which contain significant spreading ridges. Under these conditions, the mechanical weakness of the serpentinized mantle and the hyper-thinned continental lithosphere serve as focal points for the initiation of convergence and downward thrusting of these basins beneath passive continental boundaries [7,[30][31][32]. The main features for recognizing Ampferer-type subductions are (i) coherent structural units or nappes (flake tectonics) transported over long distances modified by moderate deformation and comprising the (ultra-) high-pressure continental and oceanic fragments and (ii) the lack of Penrose-type oceanic crustal fragments [7,38].…”

Section: The Ampferer-type Subduction: Convergence and Assembly Of Th...mentioning

confidence: 99%

“…The Ampferer-type (or A-type) subduction occurs when a continent or large island collides with another continent by subducting hyperextended continental basins that contain minor oceanic crust formed at rift margins [7,8,20]. These hyper-thinned basins and their mechanically weak serpentinized mantle beneath serve as focal points for initiating convergence and down-thrusting of these basins beneath passive margins [7,20,[30][31][32]. Only the dry root lithosphere is subducting, while hydrated lithologies from the descending plate (hydrated mantle rocks and sedimentary deposits) are sequentially accreted into a nascent orogenic wedge, resulting in amagmatic closure associated with tremendous deformation of preexisting continental rocks, forcing the material upward, creating high mountains [7,[32][33][34].…”

Section: Introductionmentioning

confidence: 99%

The Ampferer-Type Subduction: A Case of Missing Arc Magmatism

El-Rus¹,

Khudier²,

Hamid³

et al. 2023

Updates in Volcanology - Linking Active Volcanism and the Geological Record

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Ampferer-type subduction is a term that refers to the foundering of hyper-extended continental or embryonic oceanic basins (i.e., ocean-continent transitions) at passive continental margins. The lithospheric mantle underlying these rift basins is mechanically weaker, less dense, and more fertile than the lithospheric mantle underlying bounded continents. Therefore, orogens resulting from the closure of a narrow, immature extensional system are essentially controlled by mechanical processes without significant thermal and lithologic changes. Self-consistent, spontaneous subduction initiation (SI) due to the density contrast between the lithosphere and the crust of ocean-continent transitions is unlikely to occur. Additional far-field external horizontal forces are generally required for the SI. When the lithosphere subducts, the upper crust or serpentinized mantle and sediments separate from the lower crust, which becomes accreted to the orogen, while the lower crust subducts into the asthenosphere. Subduction of the lower crust, which typically consists of dry lithologies, does not allow significant flux-melting within the mantle wedge, so arc magmatism does not occur. As a result of melting inhibition within the mantle wedge during Ampferer-type subduction zones, the mantle beneath the resulting orogenic belts is fertile and thus has a high potential for magma generation during a subsequent breakup (i.e., magma-rich collapse).

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“…In panel "e", the corresponding crustal-scale pro-and retro-shear zones are labelled by "p" and "r". Oppositely dipping thrust faults have been commonly reproduced in previous 2D(Vogt et al, 2017;Auzemery et al, 2021) and 3D(Braun & Yamato, 2010;Ruh et al, 2013) numerical studies investigating the accumulation and localization of deformation in convergent geodynamic environments [Colour figure can be viewed at wileyonlinelibrary.com]…”

mentioning

confidence: 99%

Plate corner subduction and rapid localized exhumation: Insights from3Dcoupled geodynamic and geomorphological modelling

2022

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Plate corners represent narrow, bent segments of the boundary between lithospheric plates (Figure 1a). The transition zones separating the longer, straight to slightly concave zones of plate convergence (subduction or continental collision) are termed as "syntaxial orogens" (Bendick & Ehlers, 2014). Quasi-circular patterns of young thermochronometer ages (also called bull's eye structures) found in the "syntaxial orogens" such as Southeast Alaska (Berger

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Influence of magma-poor versus magma-rich passive margins on subduction initiation

Cited by 7 publications

References 87 publications

Inverted Magma-rich Versus Magma-poor Rifted Margins: Implications for Early Orogenic Systems

Inverted Magma-rich Versus Magma-poor Rifted Margins: Implications for Early Orogenic Systems

The Ampferer-Type Subduction: A Case of Missing Arc Magmatism

Plate corner subduction and rapid localized exhumation: Insights from3Dcoupled geodynamic and geomorphological modelling

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