Exhumation Processes in Oceanic and Continental Subduction Contexts: A Review

Guillot, Stéphane; Hattori, Kéiko; Agard, Philippe; Schwartz, Stéphane; Vidal, Olivier

doi:10.1007/978-3-540-87974-9_10

Cited by 226 publications

(233 citation statements)

References 172 publications

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“…Most continental crustal UHP rocks record pressures between 2.5 and 4.0 GPa (Hacker, 2006;Guillot et al, 2009). The most extreme pressures, up to ∼ 6 GPa, documented in terranes such as the Kokchetav Massif and Norway's Western Gneiss Region, are commonly recorded in garnet-bearing peridotite bodies hosted within rocks of continental crustal origin, rather than within the host rocks themselves (e.g.…”

Section: Pressures and Temperaturesmentioning

confidence: 99%

“…The crystallization of these minerals in high-strain zones may help localize deformation and initiate decoupling of buoyant crust from the subducting slab. The formation of discrete weak shear zones may also protect stronger lenses and boudins of UHP material from penetrative deformation, assisting in the preservation of UHP indicator minerals (Guillot et al, 2009). …”

Section: Hydration Weakeningmentioning

confidence: 99%

“…Guillot et al, 2009). Field observations, geochemical and geochronological analyses, and conceptual, analytical and numerical models suggest that these different tectonic environments exhume high-pressure rocks at different rates and by different, competing mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Exhumation of (ultra-)high-pressure terranes: concepts and mechanisms

Warren

2013

Solid Earth

113

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Abstract. The formation and exhumation of high and ultrahigh-pressure, (U)HP, rocks of crustal origin appears to be ubiquitous during Phanerozoic plate subduction and continental collision events. Exhumation of (U)HP material has been shown in some orogens to have occurred only once, during a single short-lived event; in other cases exhumation appears to have occurred multiple discrete times or during a single, long-lived, protracted event. It is becoming increasingly clear that no single exhumation mechanism dominates in any particular tectonic environment, and the mechanism may change in time and space within the same subduction zone. Subduction zone style and internal force balance change in both time and space, responding to changes in width, steepness, composition of subducting material and velocity of subduction. In order for continental crust, which is relatively buoyant compared to the mantle even when metamorphosed to (U)HP assemblages, to be subducted to (U)HP conditions, it must remain attached to a stronger and denser substrate. Buoyancy and external tectonic forces drive exhumation, although the changing spatial and temporal dominance of different driving forces still remains unclear. Exhumation may involve whole-scale detachment of the terrane from the subducting slab followed by exhumation within a subduction channel (perhaps during continued subduction) or a reversal in motion of the entire plate (eduction) following the removal of a lower part of the subducting slab. Weakening mechanisms that may be responsible for the detachment of deeply subducted crust from its stronger, denser substrate include strain weakening, hydration, melting, grain size reduction and the development of foliation. These may act locally to form narrow high-strain shear zones separating stronger, less-strained crust or may act on the bulk of the subducted material, allowing whole-scale flow. Metamorphic reactions, metastability and the composition of the subducted crust all affect buoyancy and overall strength. Future research directions include identifying temporal and spatial changes in exhumation mechanisms within different tectonic environments, and determining the factors that influence those changes.

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Section: Pressures and Temperaturesmentioning

confidence: 99%

Section: Hydration Weakeningmentioning

confidence: 99%

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Exhumation of (ultra-)high-pressure terranes: concepts and mechanisms

Warren

2013

Solid Earth

113

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“…It was primarily focused on the plate interface interaction in oceanic subduction zones, and now it has being extended to continental subduction zone [7]. Although this concept has been used in studying the occurrence of metamorphic rocks in oceanic subduction zones [8][9][10], it is just at the beginning of its application to continental collision orogens. Despite the difference in the tectonic mechanism for subduction and exhumation of continental curst, it is certain that crustal and mantle materials at the place interface are variably detached into subduction channel during the processes of subduction and exhumation.…”

mentioning

confidence: 99%

Continental subduction channel processes: Plate interface interaction during continental collision

2013

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The study of subduction-zone processes is a key to development of the plate tectonic theory. Plate interface interaction is a basic mechanism for the mass and energy exchange between Earth's surface and interior. By developing the subduction channel model into continental collision orogens, insights are provided into tectonic processes during continental subduction and its products. The continental crust, composed of felsic to mafic rocks, is detached at different depths from subducting continental lithosphere and then migrates into continental subduction channel. Part of the subcontinental lithospheric mantle wedge, composed of peridotite, is offscrapped from its bottom. The crustal and mantle fragments of different sizes are transported downwards and upwards inside subduction channels by the corner flow, resulting in varying extents of metamorphism, with heterogeneous deformation and local anatexis. All these metamorphic rocks can be viewed as tectonic melanges due to mechanical mixing of crust-and mantle-derived rocks in the subduction channels, resulting in different types of metamorphic rocks now exposed in the same orogens. The crust-mantle interaction in the continental subduction channel is realized by reaction of the overlying ancient subcontinental lithospheric mantle wedge peridotite with aqueous fluid and hydrous melt derived from partial melting of subducted continental basement granite and cover sediment. The nature of premetamorphic protoliths dictates the type of collisional orogens, the size of ultrahigh-pressure metamorphic terranes and the duration of ultrahigh-pressure metamorphism. In continental collision orogens, exposed ultrahigh-pressure (UHP) metamorphic terranes contain the lithotectonic records of Alpine-type subduction [1]. These records highlight metamorphic P-T conditions and mass transfers, indicating subduction of continental crustal rocks to mantle depths of over 100 km. The UHP terranes are characterized by minor occurrences of mafic eclogites and ultramafic peridotites that are hosted by felsic gneisses. Such UHP eclogite-facies parageneses are absent in Pacific-type subduction zones [2]. These UHP rocks are of crustal and mantle protoliths and now occur together with their lower pressure counterparts in continental collision orogens [3]. It is intriguing how the continental crust is subducted to mantle depths for UHP metamorphism, how UHP slices are exhumed from mantle depths to crustal levels, and how metamorphic rocks of different P-T conditions occur together in the same orogens. The property of plate interface in subduction zones is a key to physical and chemical interactions at interplate boundaries. Physical and chemical transfers at convergent plate margins can occur on various spatial and temporal scales, which is fundamental to subduction-zone processes. Like the plate tectonic theory, the concept of subduction channel was originally developed from the tectonics of oceanic subduction zone [4][5][6]. It was primarily focused on the plate interface interaction in ocean...

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“…Dal Piaz 1972;Cloos 1982;Platt 1986Platt , 1993Shreve & Cloos 1986;Cloos & Shreve 1988;Polino et al 1990;Tao & O'Connell 1992;Spalla et al 1996;Duchene et al 1997;Guillot et al 2009;Maierovà et al 2016).…”

Section: Introductionmentioning

confidence: 99%

2-D numerical study of hydrated wedge dynamics from subduction to post-collisional phases

Regorda¹,

Roda²,

Marotta³

et al. 2017

Geophysical Journal International

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S U M M A R YWe developed a 2-D finite element model to investigate the effect of shear heating and mantle hydration on the dynamics of the mantle wedge area. The model considers an initial phase of active oceanic subduction, which is followed by a post-collisional phase characterized by pure gravitational evolution. To investigate the impact of the subduction velocity on the thermomechanics of the system, three models with different velocities prescribed during the initial subduction phase were implemented. Shear heating and mantle hydration were then systematically added into the models. We then analysed the evolution of the hydrated area during both the subduction and post-collisional phases, and examined the difference in P max -T (maximum pressure-temperature) and P-T max (pressure-maximum temperature) conditions for the models with mantle hydration. The dynamics that allow for the recycling and exhumation of subducted material in the wedge area are strictly correlated with the thermal state at the external boundaries of the mantle wedge, and the size of the hydrated area depends on the subduction velocity when mantle hydration and shear heating are considered simultaneously. During the post-collisional phase, the hydrated portion of the mantle wedge increases in models with high subduction velocities. The predicted P-T configuration indicates that contrasting P-T conditions, such as Barrovian-to Franciscan-type metamorphic gradients, can contemporaneously characterize different portions of the subduction system during both the active oceanic subduction and post-collisional phases and are not indicative of collisional or subduction phases.

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Exhumation Processes in Oceanic and Continental Subduction Contexts: A Review

Cited by 226 publications

References 172 publications

Exhumation of (ultra-)high-pressure terranes: concepts and mechanisms

Exhumation of (ultra-)high-pressure terranes: concepts and mechanisms

Continental subduction channel processes: Plate interface interaction during continental collision

2-D numerical study of hydrated wedge dynamics from subduction to post-collisional phases

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