Exhumation of high‐pressure metamorphic rocks in a subduction channel: A numerical simulation

Gerya, Taras; Stöckhert, Bernhard; Perchuk, A. L.

doi:10.1029/2002tc001406

Cited by 702 publications

(647 citation statements)

References 115 publications

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“…Although some of the above variables have been explored previously [Gerya et al, 2002[Gerya et al, , 2008Warren et al, 2008aWarren et al, , 2008bYamato et al, 2008;Sizova et al, 2012], few studies have addressed the influence of these factors specifically in the context of Alpine-type orogens, and none has produced a quantitative working model that explains the essential tectonic features of the Western Alps.…”

Section: Key Pointsmentioning

confidence: 99%

The Alps 2: Controls on crustal subduction and (ultra)high‐pressure rock exhumation in Alpine‐type orogens

2014

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Building on our previous results, we use 2-D upper mantle-scale thermomechanical numerical models to explore key controls on the evolution of Alpine-type orogens and the Alps per se, focusing on (ultra)high-pressure ((U)HP) metamorphic rocks. The models show that UHP rocks form and exhume by burial and subsequent buoyant ascent of continental crust in the subduction conduit. Here we test the sensitivity of the models to surface erosion rate, crustal heat production, plate convergence/divergence rates, geometry of the subducting continental margin, and strength of the retrocontinent. Surface erosion affects crustal exhumation but not early buoyant exhumation. Metamorphic temperatures increase with crustal radioactive heat production. Maximum burial depth prior to exhumation increases with plate convergence rates, but exhumation rates are only weakly dependent on subduction rates. Onset of absolute plate divergence does not trigger exhumation in these models. We conclude that contrasting peak pressures, exhumation rates, and volumes of (U)HP crust exhumed in the Alps orogen primarily reflect along-strike contrasts in the geometry, thermal structure, and/or strength of the subducting microcontinent (Briançonnais) and continental (European margin) crust. The experiments also support the interpretation that the Western Alps (U)HP Internal Crystalline Massifs exhumed as composite, stacked plumes and that these plumes drove local crustal extension during orogen-scale shortening. For weak upper plate retrocrusts, postexhumation retrothrusting forms a retrowedge. Overall, these results are consistent with predictions using the exhumation number (ratio of buoyancy to side traction forces in the conduit), which expresses the combined parameter control of the depth/volume of crustal subduction and the transition to buoyant exhumation.

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Section: Key Pointsmentioning

confidence: 99%

The Alps 2: Controls on crustal subduction and (ultra)high‐pressure rock exhumation in Alpine‐type orogens

2014

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“…In addition, deformational experiments on serpentine minerals suggest that even slight degrees of serpentinization, enhances shear localization [e.g., Escartín et al, 1997] and drastically weakens the peridotite [e.g., Escartín et al, 2001]. These physical properties of serpentine are considered to promote both the detachment of ultramafic rocks from mantle wedge and buoyant flow reverse to subduction [e.g., Schwartz et al, 2001;Gerya et al, 2002].…”

Section: Serpentine Formation: a Trigger To Exhumationmentioning

confidence: 99%

“…[43] It is generally accepted that serpentine is important for dynamic processes in subduction zone because of wide stability in mantle lithosphere [e.g., Ulmer and Trommsdorff, 1999;Seno et al, 2001;Bostock et al, 2002] and relatively weak mechanical properties [e.g., Raleigh and Paterson, 1965;Gerya et al, 2002]. Particularly its contribution to exhumation processes has been discussed on the basis of numerous geological and structural studies [e.g., Takasu, 1989;Hermann et al, 2000;Guillot et al, 2000].…”

Section: Serpentine Formation: a Trigger To Exhumationmentioning

confidence: 99%

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

Mizukami

Wallis

2005

Tectonics

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[1] The Higashi-akaishi peridotite body in the Sanbagawa metamorphic belt is a unique example of a kilometer-scale body including garnet-lherzolite facies rocks from an oceanic subduction-type orogen. In this body, four distinct deformational phases D 1 , D 2 , D 3 , and D 4 can be defined. The tectonic significance of D 1 is unclear. Microstructural observations and application of garnet-orthopyroxene geothermobarometry suggest that D 2 took place during high-temperature subduction up to depths of $100 km (from 2.3 GPa to above 2.8 GPa at temperature of 700-800°C) or more. D 3 represents a major phase of exhumation. After exhumation the Higashi-akaishi body became juxtaposed with the adjacent Besshi and Eclogite units at a depth of around 35 km (1 GPa). The common history of the two units after D 3 is shown by the intertectonic growth of tremolite between D 3 and D 4 that corresponds to a stage of intertectonic growth of plagioclase in the Besshi and Eclogite units. Both the spatial distribution and the estimated pressuretemperature (P-T) conditions of this intertectonic phase of mineral growth in the different units are in excellent agreement. The development of an antigorite schistosity during the late stage of D 2 indicates an anticlockwise P-T path with cooling at depths of around 100 km. The association of the antigorite-bearing fabric and the onset of exhumation after the D 2 stage suggest that the density decrease due to antigorite formation may have been sufficient to trigger the exhumation of dense ultramafic body from UHP conditions in subduction zones. Syn-D 2 water introduction and the anticlockwise P-T path are expected when convection in the mantle wedge brings peridotite toward a subduction boundary through mantle wedge or when peridotite is dragged down along a subduction boundary that is progressively cooling immediately after initiation of subduction. Citation: Mizukami, T., and S. R. Wallis (2005), Structural and petrological constraints on the tectonic evolution of the garnet-lherzolite facies Higashi-akaishi peridotite body, Sanbagawa belt, SW Japan, Tectonics, 24, TC6012,

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“…The oceanic plate is then dehydrated because of the increased temperature and pressure (Schmidt & Poli 1998;Liu et al 2007;Faccenda et al 2009;Faccenda & Mancktelow 2010). The water released by the slab hydrates the mantle wedge and can lead to its serpentinization and to a decrease in viscosity (Gerya et al 2002;Honda & Saito 2003;Arcay et al 2005). We simulate the rheological weakening of the mantle wedge by assuming a constant viscosity of 10 19 Pa s and a density of 3000 kg m −3 for the mantle occurring at the pressure and temperature conditions described by the stability field of serpentine (Honda & Saito 2003;Arcay et al 2005;Gerya & Stoeckert 2006;Roda et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Gerya et al 2002;Gorczyk et al 2006Gorczyk et al , 2007Yamato et al 2007;Ernst & Liou 2008;Agard et al 2009;Meda et al 2010;Roda et al 2010Roda et al , 2012Le Voci et al 2014). In ocean-continent sub-Q3 Q4 duction systems, low viscosity hydrated mantle facilitates the exhumation and underplating of subducted oceanic and continental material at the base of the crust of the upper plate (Billen & Gurnis 2001;Hirth & Kohlstedt 2003;Billen 2008;Hirth & Guillot 2013;Nagaya 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 of high‐pressure metamorphic rocks in a subduction channel: A numerical simulation

Cited by 702 publications

References 115 publications

The Alps 2: Controls on crustal subduction and (ultra)high‐pressure rock exhumation in Alpine‐type orogens

The Alps 2: Controls on crustal subduction and (ultra)high‐pressure rock exhumation in Alpine‐type orogens

Structural and petrological constraints on the tectonic evolution of the garnet‐lherzolite facies Higashi‐akaishi peridotite body, Sanbagawa belt, SW Japan

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

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