Strain heating and thermal softening in continental shear zones: a review

Brun, Jean; Cobbold, P.R.

doi:10.1016/0191-8141(80)90045-0

Cited by 158 publications

(77 citation statements)

References 35 publications

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“…The strain softening is associated with the weakening effect of plastic-flow belts, which, as one of the reasons, is due to the frictional heat production [36][37][38][39]. The studies [19,20] indicate that the shear thermal effect of plastic-flow belt in the lower lithosphere is the main origin of the positive heat-flow anomaly in the central-eastern Asian continent.…”

Section: Weakening Effect Of Plastic-flow Beltmentioning

confidence: 97%

Numerical simulation of ductile shear localization: Plastic‐flow network and slip‐line field

Shengzu

Sun

Ning

2007

Num Anal Meth Geomechanics

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SUMMARYThe development of plastic-flow network (PFN) in plane-strain elastoplastic medium indented locally is simulated using the finite element method, in which the von Mises criterion and a constitutive relation with post-yield softening are used. The results of simulations show that the development process of PFN, which is composed of two families of plastic-flow belts (i.e. ductile shear zones or shear bands) intersecting each other, includes the stages of locally-compacting (I), PFN-spreading (IIa + IIb) and surface-bulging (III). PFN is similar to but different from the traditional slip-line network (slip-line field) that the various solutions of slip-line field correspond only to some critical states of PFN. PFN occurring in elastoplastic medium can be considered as a PFN in viscoplastic medium with high viscosity or high strain rate and both of them are identical in some basic aspects, such as the conjugate angles equal to or greater than 90 • , the direction of the maximum compressive stress in coincidence with the bisector of conjugate angle, the evolution of triangular compacted area, the ingeneration of discontinuity, the weakening effect of the belts and the plastic-flow background of PFN. The simulations of the simplified models stated in this paper provide a basis for the further studies of numerical simulations of PFN, especially those in viscoplastic medium.

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Section: Weakening Effect Of Plastic-flow Beltmentioning

confidence: 97%

Numerical simulation of ductile shear localization: Plastic‐flow network and slip‐line field

Shengzu

Sun

Ning

2007

Num Anal Meth Geomechanics

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“…Many examples of such a structural control of igneous complexes in general and granites in particular have been reviewed by PITCHER (1979, p. 645) who suggests that 'deep faults promote partial melting by rapid pressure reduction, by providing low pressure zones towards which new magma would migrate and towards which it would be focused and into which it would be funnelled'. Initial interactions between granite ridges and transcurrent faults have often been encountered, for instance in the South Armorican Shear Zone which shows synchronous association with several leucogranite plutons (JEGOUZO, 1980;BRUN, 1981). It is unlikely that deep faults can lower the pressure and that shear-heating can produce partial melting (BRUN & COB-BOLD, 1980).…”

Section: Initiationmentioning

confidence: 97%

Kinematics of large syn-orogenic intrusions: example of the Lower Proterozoic Saraya batholith (Eastern Senegal)

1992

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ZusammenfassungDer groge Saraya Batholith intrudierte in die unterproterozoischen Schichten des 6stlichen Senegals. Die Geftigeanalyse zeigt, dag dieger groge, granitische Batholith einem zusammengesetzten K6rper entspricht, der aug mehreren zusammengewachsenen Plutonen mit zwischengeschalteten Diapiren besteht. Die Interpretation des strukturellen Geftigemusters in diesen Plutonen und in den umgebenden Gesteinen liefert die Basis ftir ein hypothetisches Modell ftir den Beginn, den Aufstieg und die Platznahme des Plutons wie folgt: 1. Entwicklung eines tiefen N-S orientierten Rtickens in Abhfingigkeit von einer wichtigen Krustenfraktur, welche aug einer frtiheren Dehnungsphase durch eine Horizontalverschiebung reaktiviert wurde. Diese hat wahrscheinlich die Absonderung, Ansammlung und den Aufstieg des Magmas erleichtert. 2. Die Intrusion und das Aufsplittern des Rtickens in einige Diapire, erm6glichte dag simultane und separate Aufsteigen, in einer Anordnung von N-S gerichteten sinistralen Transversalverschiebungen, die eine NW-SE Verengung und eine verstfirkte Platznahme der Plutone initiierte. 3. Die endgtiltige Platznahme wird charakterisiert durch dag Wechselspiel zwischen regionaler Deformation und plutonischer ,,Aufblfihung~<. Letztere ftihrte zu einem Zusammenwachsen der Intursionen, und zur Bildung eines gr6geren, scheinbar homogenen K6rpers. Dieses Modell kann erweitert werden auf die anderen gr6geren Birimian Batholithe des Unteten Proterozoikums im 6stlichen Senegal. AbstractThe large Saraya batholith intruded the Lower Proterozoic sequences of Eastern Senegal. Structural analysis indicates that this large granitic batholith corresponds to a composite body consisting of several coalescent plutons and interfering diapirs. Interpretation of the structural fabric patterns in these plutons and in the host-rocks constitutes the basis of a hypothetical model of initiation, ascent and emplacement as follows: (1.) development of a deep N-S granitic ridge controled by a major crustal fracture generated by an earlier extensional phase re-activated by a strike-slip fault which, probably, would facilitate segregation, collection and ascent of magmas; (2.) intrusion and splitting up of the ridge into several diapirs which ascended simultaneously and separately in a setting of a N-S sinistral transcurrent deformation inducing a transverse NW-SE shortening and forceful emplacement of plutons and (3.) final emplacement characterized by interference between regional deformation and pluton 'ballooning', the latter leading to the coalescence of intrusions and to the formation of a larger, apparently homogeneous body.This model could be extended to the other large Birimian batholiths of the Lower Proterozoic in Eastern Senegal.

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“…Shear heating Hs results from the transformation of mechanical energy into heat during deformation and is recognised as a major component of the total energy budget (e.g., Brun and Cobbold, 1980;Lachenbruch and Sass, 1980;Chester et al, 2005). Shear heating is a function of the strain rate and stress tensors ( ij and σ ij respectively) and is computed according to the following equation:…”

Section: Computation Methodsmentioning

confidence: 99%

“…However, this is a simplification and other energy transfers should be taken into account and their influence on the formation and preservation of the inverted thermal gradient tested. (i) The energy dissipated during a continuous deformation is not entirely converted into heat but can also be used to change the physical properties of the rock inside the sheared area (e.g., the rock microstructure; Brun and Cobbold, 1980). (ii) Metamorphic reactions occurring within and astride the shear zone can significantly consume or release heat (Oxburgh and Turcotte, 1976;Anderson et al, 1978;DeVore, 1983;Peacock, 1987aPeacock, , b, 1990).…”

Section: Shear Heating the Key Parametermentioning

confidence: 99%

“…Shear heating constitutes a part of the conservation of energy and a study of the thermal evolution around a thrust during its activity requires to take into account the relative displacement between the two crustal blocks as a source of heat (Toksöz et al, 1971;Brun and Cobbold, 1980;Pavlis, 1986). By considering shear heating in the viscous way, two parameters have to be examined: the strain rate and the effective viscosity η within the thrust (section 2.2, Eq.…”

Section: Shear Heating Effectsmentioning

confidence: 99%

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Major role of shear heating in intracontinental inverted metamorphism: Inference from a thermo-kinematic parametric study

2013

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role of shear heating in intracontinental inverted metamorphism: Inference from a thermo-kinematic parametric study. Tectonophysics, Elsevier, 2013, 608, pp.812-831. 10.1016/j.tecto.2013 1 Major role of shear heating in intracontinental inverted metamorphism:Inference from a thermo-kinematic parametric study. AbstractInverted metamorphism corresponds to the stacking of high-temperature metamorphic units structurally on top of lower-temperature units and is commonly observed along main thrusts in major orogens. Yet, in spite of many existing models, the origin and preservation of the metamorphic inversion in intracontinental collision belts is still debated. In this study, we use a crustal-scale 2D thermo-kinematic model in order to investigate the key parameters controlling the inversion of the geothermal gradient at crustal scale. Our results confirm that the kinematic framework strongly impacts the thermal evolution around the thrust. Erosion velocity and thermal conductivity of rocks are two parameters that control the spatial location of the thermal perturbation and the intensity of inversion, respectively. However, even in extreme kinematic configurations, i.e., convergence velocities > 3cm.yr 3

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Strain heating and thermal softening in continental shear zones: a review

Cited by 158 publications

References 35 publications

Numerical simulation of ductile shear localization: Plastic‐flow network and slip‐line field

Numerical simulation of ductile shear localization: Plastic‐flow network and slip‐line field

Kinematics of large syn-orogenic intrusions: example of the Lower Proterozoic Saraya batholith (Eastern Senegal)

Major role of shear heating in intracontinental inverted metamorphism: Inference from a thermo-kinematic parametric study

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