Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks

Platt, J. P.

doi:10.1130/0016-7606(1986)97<1037:doowat>2.0.co;2

Cited by 1,238 publications

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“…It assumes that magmas that exhibit geochemical systematics that are characteristic of suprasubduction zone magmas did in fact form above a subduction zone and that the consistent progression of magma series within all SSZ ophiolites worldwide results from the operation of a physical process that progresses in a consistent and repeatable fashion. It should be noted, however, that these stages may overlap in time and may even be diachronous; that is, the initiation of each proposed stage may migrate toward the trench in concert with hinge rollback, and several stages may be active simultaneously at different [Platt, 1986]. The life cycle of the CRO is illustrated in Figure 2; locations discussed in the text are shown in Figure 3.…”

Section: Discussionmentioning

confidence: 99%

“…As material is accreted in the subduction zone beneath the ophiolite, the ophiolite is progressively elevated, until gravitational collapse of the accretionary complex begins to exhume rocks subjected to high-pressure metamorphism, while the overlying ophiolite is preserved in the upper plate of the detachment fault. The implications of this process have been discussed by Platt [1986], Jayko et al [1987], and Harms et al [1992]. During its life overlying the accretionary complex the ophiolite may undergo several cycles of uplift and detachment faulting.…”

Section: Stage 5: Resurrectionmentioning

confidence: 99%

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Birth, death, and resurrection: The life cycle of suprasubduction zone ophiolites

Shervais

2001

Geochem Geophys Geosyst

460

275

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[1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation of the ophiolite above a nascent or reconfigured subduction zone; this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex; (2) youth, during which is continued melting of refractory asthenosphere (depleted during birth) occurs in response to fluid flux from the subducting slab, with extensional deformation of the older plutonic suite, eruption of refractory lavas, and the intrusion of wehrlite-pyroxenite; (3) maturity, with the onset of semistable arc volcanism, typically calc-alkaline, as the subduction zone matures and stabilizes, and the intrusion of quartz diorite and eruption of silicic lavas; and (4) death, which is the sudden demise of active spreading and ophiolite-related volcanism, which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis; expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites; (5) resurrection, with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction. The early stages (1± 3) may be diachronous, and each stage may overlap in both time and space. The existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the SSZ tectonic setting.

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Section: Discussionmentioning

confidence: 99%

Section: Stage 5: Resurrectionmentioning

confidence: 99%

Birth, death, and resurrection: The life cycle of suprasubduction zone ophiolites

Shervais

2001

Geochem Geophys Geosyst

460

275

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“…Platt, 1986;Malavieille, 1997;Jolivet and Goffé, 2000). Extensional structures formed both during and following regional contraction can coexist along the same cross section of an orogen (Jolivet and Goffé, 2000).…”

Section: Extension Contemporaneous With Thrusting In Orogenic Beltsmentioning

confidence: 99%

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Harris

Koyi

Fossen

2002

Earth-Science Reviews

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This review of structures developed in extensional high-grade terrains, combined with results of centrifuge analogue modelling, illustrates the range of fold styles and mechanisms for folding of amphibolite to granulite facies rocks during rifting or the collapse of a thrust-thickened orogen. Several extensional fold mechanisms (such as folding within detachment shear zones) are similar to those in contractional settings. The metamorphic P -T -t path, and not fold style or mode of formation, is therefore required to determine the tectonic setting in which some folds developed. Other mechanisms such as rollover above and folding between listric normal shear zones, and folding due to isostatic adjustments during crustal thinning, are unique to extensional tectonic settings. Several mechanisms for folding during crustal extension produce structures that could easily be misinterpreted as implying regional contraction and hence lead to errors in their tectonic interpretation. It is shown that isoclinal recumbent folds refolded by open, upright folds may develop during regional extension in the deep crust. Folds with a thrust sense of asymmetry can develop due to high shear strains within an extensional detachment, or from enhanced back-rotation of layers between normal shear zones. During back-rotation folding, layers rotated into the shortening field undergo further buckle folding, and all may rotate towards orthogonality to the maximum shortening direction. This mechanism explains the presence of many transposed folds, folds with axial planar pegmatites and folds with opposite vergence in extensional terrains. Examples of folds in high-grade rocks interpreted as forming during regional extension included in this paper are from the Grenville Province of Canada, Norwegian

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“…During this circulation, the metamorphic rocks in general undergo extensive synmetamorphic deformation. Viscous flow and deformation at depths, associated with brittle or plastic deformation at relatively shallow levels and erosion at the surface (Figure 1), are thought to be important for understanding the deformation at plate boundaries, including exhumation of the metamorphic rocks, orogeny, and active deformation [e.g., Platt, 1986;Beaumont et al, 1996;Maruyama et al, 1996;England and Molnar, 1997;Ring et al, 1999].…”

Section: Introductionmentioning

confidence: 99%

“…[8] Three main mechanisms which drive the viscous flow have been proposed for the accretionary wedge and the forearc region as a weak deforming zone between the plates [e.g., Cloos, 1982;Toriumi, 1985;Platt, 1986;Otsuki, 1992;Beaumont et al, 1994;Maruyama et al, 1996;Wintsch et al, 1999;Feehan and Brandon, 1999]: (1) squeezing between the parallel or hinged boundaries by reducing the distance or the angle between the boundaries; (2) corner flow in the forearc wedge by dragging of the subducting plate with a rigid backstop (viscous coupling is required between the subducting plate and the overlying wedge); and (3) mass accretion and underplating to the wedge system (Figure 1). The viscous flow corresponding to each driving force should result in different deformation, i.e., rock textures, geological structures and their distributions.…”

Section: Introductionmentioning

confidence: 99%

Viscous flow and deformation of regional metamorphic belts at convergent plate boundaries

Iwamori

2003

J. Geophys. Res.

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[1] Viscous flow and deformation of a Newtonian fluid between rigid boundaries have been modeled for investigating deformation of a forearc wedge and a regional metamorphic belt as a weak deforming zone between the plates at convergent boundaries. Three types of analytic formulations together with numerical formulations for a Newtonian fluid with a constant viscosity are used for investigating various flows and deformation: (1) flows induced by squeezing between two parallel boundaries, (2) flows induced by squeezing and heterogeneous mass influx in the wedge between two oblique boundaries (e.g., accretionary wedge over the subducting plate with the continental plate as a backstop), and (3) flows induced by dragging along the boundaries and by homogeneous mass influx in the wedge as in type 2. All cases include strike-slip movements of the boundaries, which allows us to investigate three-dimensional (3-D) deformation (e.g., 3-D corner flow). The corresponding flow, deformation of infinitesimal and finite elements, and the timescale of flow are calculated for each configuration with various mechanical boundary conditions. The model results show that configuration and mechanism of the flow can be inferred from the spatial variation of finite deformation (e.g., deformed radiolarians as a strain marker and geometry of folding as finite deformation of a large block). In particular, prolate strain nearly parallel to the strike of subduction zone, together with a large-scale folding, can be a good indicator for deformation in the forearc wedge associated with 3-D corner flow induced by oblique subduction. Deformation observed in the Cretaceous regional metamorphic belts in southwest Japan can be explained by this mechanism.

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Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks

Cited by 1,238 publications

References 0 publications

Birth, death, and resurrection: The life cycle of suprasubduction zone ophiolites

Birth, death, and resurrection: The life cycle of suprasubduction zone ophiolites

Mechanisms for folding of high-grade rocks in extensional tectonic settings

Viscous flow and deformation of regional metamorphic belts at convergent plate boundaries

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