The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Zhaojie Guo - One of the best experts on this subject based on the ideXlab platform.
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cenozoic structural inversion from transtension to Transpression in yingxiong range western qaidam basin new insights into strike slip superimposition controlled by altyn tagh and eastern kunlun faults
Tectonophysics, 2018Co-Authors: Xiang Cheng, Daowei Zhang, Marc Jolivet, Runchao Liu, Zhaojie GuoAbstract:Abstract A Cenozoic structural inversion event from transtension to Transpression involving salt tectonics has been uncovered in the Yingxiong Range, the western Qaidam Basin. Seismic reflection data show that there are two common structural styles in the Yingxiong Range: (1) the positive flower structure; (2) the thrust-controlled fold at shallow depth and the positive inverted flower structure at deep levels, which are separated by a salt layer in the upper Xiaganchaigou Formation. The Yingxiong Range experienced a first stage of transtension in the Eocene, induced by the Altyn Tagh Fault, and a second stage of Transpression from the early Miocene to present, jointly controlled by the Altyn Tagh and Eastern Kunlun Faults. The Eocene transtension produced numerous NW-striking right-stepping en-echelon transtensional normal faults or fractures in the Yingxiong Range. At the same time, evaporites and mudstone were deposited in the vicinity of these faults. In the early Miocene, the Eocene transtensional normal faults were reactivated in a reverse sense, and the thrust-controlled folds at shallow depth started to form simultaneously. With Transpression enhanced in the late Cenozoic, positive flower structures directly formed in places without evaporites. The Cenozoic transtension to Transpression inversion of the Yingxiong Range is the result of strike-slip superimposition controlled by the Altyn Tagh and Eastern Kunlun Faults in time and space.
Xiang Cheng - One of the best experts on this subject based on the ideXlab platform.
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cenozoic structural inversion from transtension to Transpression in yingxiong range western qaidam basin new insights into strike slip superimposition controlled by altyn tagh and eastern kunlun faults
Tectonophysics, 2018Co-Authors: Xiang Cheng, Daowei Zhang, Marc Jolivet, Runchao Liu, Zhaojie GuoAbstract:Abstract A Cenozoic structural inversion event from transtension to Transpression involving salt tectonics has been uncovered in the Yingxiong Range, the western Qaidam Basin. Seismic reflection data show that there are two common structural styles in the Yingxiong Range: (1) the positive flower structure; (2) the thrust-controlled fold at shallow depth and the positive inverted flower structure at deep levels, which are separated by a salt layer in the upper Xiaganchaigou Formation. The Yingxiong Range experienced a first stage of transtension in the Eocene, induced by the Altyn Tagh Fault, and a second stage of Transpression from the early Miocene to present, jointly controlled by the Altyn Tagh and Eastern Kunlun Faults. The Eocene transtension produced numerous NW-striking right-stepping en-echelon transtensional normal faults or fractures in the Yingxiong Range. At the same time, evaporites and mudstone were deposited in the vicinity of these faults. In the early Miocene, the Eocene transtensional normal faults were reactivated in a reverse sense, and the thrust-controlled folds at shallow depth started to form simultaneously. With Transpression enhanced in the late Cenozoic, positive flower structures directly formed in places without evaporites. The Cenozoic transtension to Transpression inversion of the Yingxiong Range is the result of strike-slip superimposition controlled by the Altyn Tagh and Eastern Kunlun Faults in time and space.
Manuel Diazazpiroz - One of the best experts on this subject based on the ideXlab platform.
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deformation mechanics in inclined brittle ductile Transpression zones insights from 3d finite element modelling
Journal of Structural Geology, 2020Co-Authors: Seyed Tohid Nabavi, Carlos Fernández, Manuel Diazazpiroz, Leticia Barcos, Seyed Ahmad Alavi, S Mohammadi, Mohammad R Ghassemi, Marcel FrehnerAbstract:Abstract Most natural examples of Transpression zones developed at oblique convergence regime are inherently 3D and have inclined boundaries. A 3D finite element model with an elasto-plastic rheology is used to investigate the structural and mechanical evolution of inclined Transpression zones in a rock sequence above a frictional basal detachment. Inelastic constitutive relationships allow permanent strains to develop in response to the applied loads. FE-modelling results show that oblique convergence is accommodated by discrete deformation at the main pre-existing inclined faults (=70°) and by distributed brittle and ductile deformation at active blocks. Oblique contraction at the active blocks resulted mainly in layer-parallel shortening, orthogonal to the model outer boundaries, whereas thickening in the horizontal and vertical directions was accommodated via layer-parallel, fault strike-parallel extension and up-dip extrusion (i.e., inclined extrusion). Lateral extrusion should have compensated the rest and/or volume loss took place. Folding and thickening of the mobile backstop produced a non-cylindrical, asymmetric, bi-vergent anticline where permanent strains developed principally in the steep forelimb. Secondary, conjugate fault zones also accommodate oblique slip and contribute to uplift. Displacement vectors within the Transpression zone are rotated counter-clockwise (ca. 20°–30°) with respect to vectors in the fixed backstop. Areas with higher rotation values seem to correlate with those showing higher ellipticity values. The presence of pre-existing faults favored strain partitioning from the onset of deformation. FE-modelling results compared with analytical, natural example, and analogue modelling results show that our mechanical modelling can overall match inclined Transpression zones geometry that present different modes of strain partitioning and localisation.
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inclined Transpression in the neka valley eastern alborz iran
International Journal of Earth Sciences, 2017Co-Authors: Seyed Tohid Nabavi, Manuel Diazazpiroz, Christopher J TalbotAbstract:Three major nappes in the Neka Valley in the eastern Alborz Mountains of Iran allow the Cimmerian to present convergence following the oblique collision between Iran and the southern margin of Eurasia. This work reports the identification of an inclined Transpression zone recognized by field investigations and strain analyses of the geometries of formations and detailed mesoscopic structural analyses of multiple faults, folds and a cleavage. The main structures encountered include refolded recumbent asymmetric fold nappes, highly curved fold hinges, in a Transpression zone that dips 37° to the NW between boundaries thrusts striking from N050° to N060°. The β angle (the angle between the zone boundary and direction of horizontal far-field shortening) is about 80°. The north-west and south-east boundaries of this zone coincide with the Haji-abad thrust and the Shah-Kuh thrust, respectively. Fold axes generally trend NE–SW and step to both right and left as a result of strike–slip components of fault displacements. Strain analyses using Fry’s method on macroscopic ooids and fusulina deformed into oblate ellipsoids indicate that the natural strain varies between 2.1 and 3.14. The estimated angle between the maximum instantaneous strain axis (ISAmax) and the Transpression zone boundary (θ′) is between 6° and 20°. The estimated oblique convergence angle (α), therefore, ranges between 31° and 43°. The average kinematic vorticity number (W k ) is 0.6, in a zone of sinistral pure shear-dominated inclined triclinic Transpression. These results support the applicability of kinematic models of triclinic Transpression to natural brittle–ductile shear zones.
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applying a general triclinic Transpression model to highly partitioned brittle ductile shear zones a case study from the torcal de antequera massif external betics southern spain
Journal of Structural Geology, 2014Co-Authors: Manuel Diazazpiroz, Carlos Fernández, Leticia Barcos, J C Balanya, Inmaculada Exposito, Dyanna M CzeckAbstract:Abstract Oblique convergence and subsequent Transpression kinematics can be considered as the general situation in most convergent and strike-slip tectonic boundaries. To better understand such settings, progressively more complex kinematic models have been proposed, which need to be tested against natural shear zones using standardized procedures that minimise subjectivism. In this work, a protocol to test a general triclinic Transpression model is applied to the Torcal de Antequera massif (TAM), an essentially brittle shear zone. Our results, given as kinematic parameters of the transpressive flow (Transpression obliquity, ϕ; extrusion obliquity, υ; and kinematic vorticity number, Wk), suggest that the bulk triclinic transpressive flow imposed on the TAM was partitioned into two different flow fields, following a general partitioning type. As such, one flow field produced narrow structural domains located at the limits of the TAM, where mainly dextral strike-slip simple-shear-dominated Transpression took place (Outer domains, ODs). In contrast, the remaining part of the bulk flow produced pure-shear-dominated dextral triclinic Transpression at the inner part of the TAM (Inner domain, ID). A graphical method relating internal (ϕ, Wk) to far-field (dip of the shear zone boundary, δ; angle of oblique convergence, α) Transpression parameters is proposed to obtain the theoretical horizontal velocity vector ( V → ), which in the case of the TAM, ranges between 099 and 118. These results support the applicability of kinematic models of triclinic Transpression to brittle-ductile shear zones and the potential utility of the proposed protocol.
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testing the model of oblique Transpression with oblique extrusion in two natural cases steps and consequences
Journal of Structural Geology, 2013Co-Authors: Carlos Fernández, Dyanna M Czeck, Manuel DiazazpirozAbstract:Abstract Kinematic models of various types of Transpression have been used to explain fabric features and strain in many natural deformation studies. Here, a mathematical model that encompasses all monoclinic and triclinic Transpressional deformations including triclinic deformation with inclined simple shear (ϕ) and/or inclined extrusion orientations (υ) can be tested using a step-by-step approach with available field evidence. Two cases are presented. The first case from the Wabigoon–Quetico boundary in the Archean Superior Province utilizes both fabric orientation and quantified strain data. The best fit of the field evidence to the model indicates that deformation likely took place along subvertical shear zones via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (extrusion can be either east or west and υ typically indicates extrusion orientations between 0 and 50° from vertical). The second case of the South Iberian shear zone has fabric orientation data, but no quantifiable strain possibilities. The best fit of the field evidence to the model indicates that deformation likely took place along a moderately inclined shear zone via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (υ values between 0° and 80° from the true dip of the shear zone). Using this protocol in other examples of natural deformation will allow further constraints to be applied to kinematic models.
Carlos Fernández - One of the best experts on this subject based on the ideXlab platform.
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deformation mechanics in inclined brittle ductile Transpression zones insights from 3d finite element modelling
Journal of Structural Geology, 2020Co-Authors: Seyed Tohid Nabavi, Carlos Fernández, Manuel Diazazpiroz, Leticia Barcos, Seyed Ahmad Alavi, S Mohammadi, Mohammad R Ghassemi, Marcel FrehnerAbstract:Abstract Most natural examples of Transpression zones developed at oblique convergence regime are inherently 3D and have inclined boundaries. A 3D finite element model with an elasto-plastic rheology is used to investigate the structural and mechanical evolution of inclined Transpression zones in a rock sequence above a frictional basal detachment. Inelastic constitutive relationships allow permanent strains to develop in response to the applied loads. FE-modelling results show that oblique convergence is accommodated by discrete deformation at the main pre-existing inclined faults (=70°) and by distributed brittle and ductile deformation at active blocks. Oblique contraction at the active blocks resulted mainly in layer-parallel shortening, orthogonal to the model outer boundaries, whereas thickening in the horizontal and vertical directions was accommodated via layer-parallel, fault strike-parallel extension and up-dip extrusion (i.e., inclined extrusion). Lateral extrusion should have compensated the rest and/or volume loss took place. Folding and thickening of the mobile backstop produced a non-cylindrical, asymmetric, bi-vergent anticline where permanent strains developed principally in the steep forelimb. Secondary, conjugate fault zones also accommodate oblique slip and contribute to uplift. Displacement vectors within the Transpression zone are rotated counter-clockwise (ca. 20°–30°) with respect to vectors in the fixed backstop. Areas with higher rotation values seem to correlate with those showing higher ellipticity values. The presence of pre-existing faults favored strain partitioning from the onset of deformation. FE-modelling results compared with analytical, natural example, and analogue modelling results show that our mechanical modelling can overall match inclined Transpression zones geometry that present different modes of strain partitioning and localisation.
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applying a general triclinic Transpression model to highly partitioned brittle ductile shear zones a case study from the torcal de antequera massif external betics southern spain
Journal of Structural Geology, 2014Co-Authors: Manuel Diazazpiroz, Carlos Fernández, Leticia Barcos, J C Balanya, Inmaculada Exposito, Dyanna M CzeckAbstract:Abstract Oblique convergence and subsequent Transpression kinematics can be considered as the general situation in most convergent and strike-slip tectonic boundaries. To better understand such settings, progressively more complex kinematic models have been proposed, which need to be tested against natural shear zones using standardized procedures that minimise subjectivism. In this work, a protocol to test a general triclinic Transpression model is applied to the Torcal de Antequera massif (TAM), an essentially brittle shear zone. Our results, given as kinematic parameters of the transpressive flow (Transpression obliquity, ϕ; extrusion obliquity, υ; and kinematic vorticity number, Wk), suggest that the bulk triclinic transpressive flow imposed on the TAM was partitioned into two different flow fields, following a general partitioning type. As such, one flow field produced narrow structural domains located at the limits of the TAM, where mainly dextral strike-slip simple-shear-dominated Transpression took place (Outer domains, ODs). In contrast, the remaining part of the bulk flow produced pure-shear-dominated dextral triclinic Transpression at the inner part of the TAM (Inner domain, ID). A graphical method relating internal (ϕ, Wk) to far-field (dip of the shear zone boundary, δ; angle of oblique convergence, α) Transpression parameters is proposed to obtain the theoretical horizontal velocity vector ( V → ), which in the case of the TAM, ranges between 099 and 118. These results support the applicability of kinematic models of triclinic Transpression to brittle-ductile shear zones and the potential utility of the proposed protocol.
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testing the model of oblique Transpression with oblique extrusion in two natural cases steps and consequences
Journal of Structural Geology, 2013Co-Authors: Carlos Fernández, Dyanna M Czeck, Manuel DiazazpirozAbstract:Abstract Kinematic models of various types of Transpression have been used to explain fabric features and strain in many natural deformation studies. Here, a mathematical model that encompasses all monoclinic and triclinic Transpressional deformations including triclinic deformation with inclined simple shear (ϕ) and/or inclined extrusion orientations (υ) can be tested using a step-by-step approach with available field evidence. Two cases are presented. The first case from the Wabigoon–Quetico boundary in the Archean Superior Province utilizes both fabric orientation and quantified strain data. The best fit of the field evidence to the model indicates that deformation likely took place along subvertical shear zones via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (extrusion can be either east or west and υ typically indicates extrusion orientations between 0 and 50° from vertical). The second case of the South Iberian shear zone has fabric orientation data, but no quantifiable strain possibilities. The best fit of the field evidence to the model indicates that deformation likely took place along a moderately inclined shear zone via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (υ values between 0° and 80° from the true dip of the shear zone). Using this protocol in other examples of natural deformation will allow further constraints to be applied to kinematic models.
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Triclinic Transpression zones with inclined extrusion
Journal of Structural Geology, 2009Co-Authors: Carlos Fernández, Manuel Díaz-azpirozAbstract:Data from natural Transpressional shear zones reveal a large range of lineation orientations that can spread along complete girdles. One possible way to account for such a type of fabrics is variation in the extrusion direction. This work presents a new theoretical model of oblique Transpression with inclined extrusion. The model is kinematic and the flow is considered as homogeneous and steady. The angle ζ between the simple shear direction and the extrusion direction is one of the main parameters controlling the final fabric. Low values of ζ ( 40°) can generate strain ellipsoids very close to the abscissa axis of the Flinn plot. Depending on the vorticity of the flow, the finite strain and the actual value of the ζ angle, the model predicts the generation of lineation fabrics ranging from point maxima to patterns with opposite plunge senses. These patterns can display monoclinic, nearly monoclinic or clearly triclinic symmetry. Lineation patterns spreading along complete girdles can be obtained by allowing the extrusion direction to deviate less than 30° about the vertical in either direction.
Dyanna M Czeck - One of the best experts on this subject based on the ideXlab platform.
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applying a general triclinic Transpression model to highly partitioned brittle ductile shear zones a case study from the torcal de antequera massif external betics southern spain
Journal of Structural Geology, 2014Co-Authors: Manuel Diazazpiroz, Carlos Fernández, Leticia Barcos, J C Balanya, Inmaculada Exposito, Dyanna M CzeckAbstract:Abstract Oblique convergence and subsequent Transpression kinematics can be considered as the general situation in most convergent and strike-slip tectonic boundaries. To better understand such settings, progressively more complex kinematic models have been proposed, which need to be tested against natural shear zones using standardized procedures that minimise subjectivism. In this work, a protocol to test a general triclinic Transpression model is applied to the Torcal de Antequera massif (TAM), an essentially brittle shear zone. Our results, given as kinematic parameters of the transpressive flow (Transpression obliquity, ϕ; extrusion obliquity, υ; and kinematic vorticity number, Wk), suggest that the bulk triclinic transpressive flow imposed on the TAM was partitioned into two different flow fields, following a general partitioning type. As such, one flow field produced narrow structural domains located at the limits of the TAM, where mainly dextral strike-slip simple-shear-dominated Transpression took place (Outer domains, ODs). In contrast, the remaining part of the bulk flow produced pure-shear-dominated dextral triclinic Transpression at the inner part of the TAM (Inner domain, ID). A graphical method relating internal (ϕ, Wk) to far-field (dip of the shear zone boundary, δ; angle of oblique convergence, α) Transpression parameters is proposed to obtain the theoretical horizontal velocity vector ( V → ), which in the case of the TAM, ranges between 099 and 118. These results support the applicability of kinematic models of triclinic Transpression to brittle-ductile shear zones and the potential utility of the proposed protocol.
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testing the model of oblique Transpression with oblique extrusion in two natural cases steps and consequences
Journal of Structural Geology, 2013Co-Authors: Carlos Fernández, Dyanna M Czeck, Manuel DiazazpirozAbstract:Abstract Kinematic models of various types of Transpression have been used to explain fabric features and strain in many natural deformation studies. Here, a mathematical model that encompasses all monoclinic and triclinic Transpressional deformations including triclinic deformation with inclined simple shear (ϕ) and/or inclined extrusion orientations (υ) can be tested using a step-by-step approach with available field evidence. Two cases are presented. The first case from the Wabigoon–Quetico boundary in the Archean Superior Province utilizes both fabric orientation and quantified strain data. The best fit of the field evidence to the model indicates that deformation likely took place along subvertical shear zones via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (extrusion can be either east or west and υ typically indicates extrusion orientations between 0 and 50° from vertical). The second case of the South Iberian shear zone has fabric orientation data, but no quantifiable strain possibilities. The best fit of the field evidence to the model indicates that deformation likely took place along a moderately inclined shear zone via Transpression with subhorizontal simple shear (ϕ = 0–20°) and variable inclined extrusion direction (υ values between 0° and 80° from the true dip of the shear zone). Using this protocol in other examples of natural deformation will allow further constraints to be applied to kinematic models.
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physical experiments of vertical Transpression with localized nonvertical extrusion
Journal of Structural Geology, 2004Co-Authors: Dyanna M Czeck, Peter J HudlestonAbstract:Abstract Previously proposed models of vertical-walled Transpression implicitly assume that material extrudes upwards during deformation. This assumption is not necessarily valid at all scales given that: (a) in areas of diverse lithologies, local zones of relatively rigid materials may cause extruding material to deflect around those zones, and (b) ductile strain often forms anastomosing geometries of shear zones. Therefore, it is possible that a local extension direction in otherwise classic Transpression may be nonvertical for rocks deforming at depth. Using an analogue experiment, we have modeled a Transpression zone with localized nonvertical extrusion. This extrusion is accomplished by the addition of a side ‘leak’ that allows sideways extrusion in addition to vertical extrusion. The net extension direction depends on the material's position within the deforming zone, resulting in a significant range of lineation orientations with deformation. The strain patterns produced by Transpression with localized nonvertical extrusion may explain the wide array of lineation orientations found in some natural ductile Transpression zones.
