Styles of crustal deformation in compressional orogens caused by subduction of the underlying lithosphere

Beaumont, Christopher; Fullsack, Philippe; Hamilton, Juliet

doi:10.1016/0040-1951(94)90079-5

Cited by 174 publications

(112 citation statements)

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“…[58] The SE Carpathians do not show enhanced exhumation in the upper plate (the Bucovinian basement) during collision, in contrast with theoretical models of retroshear exhumation of double-vergent orogenic wedges [e.g., Beaumont et al, 1994;Schmid et al, 1996;Willett and Brandon, 2002]. This is demonstrated by the fact that the exhumation of the Bucovinian basement and the neighboring Transylvania Basin at around 9 Ma [Krézsek and Bally, 2006] was minor and exhumation was not enough to reset AFT ages (Figures 7 and 8e).…”

Section: Collision Mechanicsmentioning

confidence: 95%

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

Merten¹,

Maţenco

Foeken

et al. 2010

Tectonics

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[1] Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronology have been combined to constrain the exhumation history of the SE Carpathians. Cooling ages generally decrease from Cretaceous for the internal basement nappes (AFT ages), to Miocene-Quaternary (AFT and AHe, respectively) for the external sedimentary wedge. The AFT and AHe data show a Paleogene age cluster, which confirms a suspected but never demonstrated tectonic event. The new data furthermore suggest that the SE Carpathians have been affected by a middle Miocene exhumation phase related to continental collision, which occurred at rates of ∼0.8 mm/yr, similar to the one previously inferred for the East Carpathians. The SE Carpathian tectonic evolution, however, is overprinted by two younger exhumation events in the Pliocene-Pleistocene. The first exhumation phase (latest Miocene-early Pliocene) occurred at high exhumation rates (∼1.7 mm/yr) and is interpreted as a tectonic event and/or associated with a sea level drop in the Paratethys basins during the Messinian low stand. The youngest recorded tectonic phase suggests rapid Pleistocene exhumation (∼1.6 mm/yr) and is interpreted to represent crustal-scale shortening different in mechanics from collisional processes. The data suggest that the SE Carpathians did not develop as a typical double-vergent orogenic wedge; instead, exhumation was related to a foreland-vergent sequence of nappe stacking during collision and was subsequently followed by a large out-of-sequence shortening event truncating the already locked collisional boundary.

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Section: Collision Mechanicsmentioning

confidence: 95%

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

Merten¹,

Maţenco

Foeken

et al. 2010

Tectonics

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“…accretion) across the plate boundary (Willett et al 1993;Beaumont et al 1994;Waschbusch & Beaumont 1996). Below this point, which we denote as S, subduction of the downgoing plate occurs beneath a discrete shear zone.…”

Section: Orogenic Deformation and Tectonic Modelsmentioning

confidence: 99%

Exhumation processes

et al. 1999

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Deep-seated metamorphic rocks are commonly found in the interior of many divergent and convergent orogens. Plate tectonics can account for high-pressure metamorphism by subduction and crustal thickening, but the return of these metamorphosed crustal rocks back to the surface is a more complicated problem. In particular, we seek to know how various processes, such as normal faulting, ductile thinning, and erosion, contribute to the exhumation of metamorphic rocks, and what evidence can be used to distinguish between these different exhumation processes.In this paper, we provide a selective overview of the issues associated with the exhumation problem. We start with a discussion of the terms exhumation, denudation and erosion, and follow with a summary of relevant tectonic parameters. Then, we review the characteristics of exhumation in different tectonic settings. For instance, continental rifts, such as the severely extended Basin-and-Range province, appear to exhume only middle and upper crustal rocks, whereas continental collision zones expose rocks from 125 km and greater. Mantle rocks are locally exhumed in oceanic rifts and transform zones, probably due to the relatively thin crust associated with oceanic lithosphere.Another topic is the use of P-T-t data to distinguish between different exhumation processes. We conclude that this approach is generally not very diagnostic since erosion and normal faulting show the same range of exhumation rates, reaching maximum rates of >5-10 km Ma -1 for both processes. In contrast, ductile thinning appears to operate at significantly slower rates. The pattern of cooling ages can be used to distinguish between different exhumation processes. Normal faulting generally shows an asymmetric distribution of cooling ages, with an abrupt discontinuity at the causative fault, whereas erosional exhumation is typically characterized by a smoothly varying cooling-age pattern with few to no structural breaks. Last, we consider the challenging problem of ultrahigh-pressure crustal rocks, which indicate metamorphism at depths greater than 100-125 kin. Understanding the exhumation of these rocks requires that we first know where and how they were formed. One explanation is that metamorphism occurred within a thickened crustal root, but it does seem unlikely that the crust, including an eclogitized mafic lower crust, could get much thicker than c. 110 km while maintaining a reasonable Moho depth (<70 km, assuming that the seismically defined Moho would be observed to lie above the eclogitized lower crust). Diamondbearing crustal rocks cannot be explained by this scheme. The alternative is to accrete the upper 10-40 km of lithospheric mantle into the orogenic root. This scenario will provide sufficient pressures for both coesite-and diamond-bearing eclogite-facies metamorphism, while maintaining a reasonable Moho depth (<70 km) and reasonable mean topography (<3 kin). We speculate that the detachment and foundering of the mantle root may contribute to the exhumation of any crust...

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“…[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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Styles of crustal deformation in compressional orogens caused by subduction of the underlying lithosphere

Cited by 174 publications

References 6 publications

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

Exhumation processes

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

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