Vorticity analysis in calcite tectonites: An example from the Attico-Cycladic massif (Attica, Greece)

Spanos, D.; Xypolias, P.; Koukouvelas, Ioannis

doi:10.1016/j.jsg.2015.08.014

Cited by 15 publications

(21 citation statements)

References 64 publications

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“…11). Antithetically rotated calcite c-axis maxima are commonly attributed to e-twinning, whereas symmetric or synthetically rotated c-axis maxima are characteristic of samples in which intracrystalline slip dominates over deformation twinning (e.g., Schmid et al, 1987;Lafrance et al, 1994;Trullenque et al, 2006;Spanos et al, 2015). Twinned recrystallized calcite grains are common in all of the Battleship Peak marble mylonite samples, and because we did not distinguish twinned grains from non-twinned grains in the pole figures, we suggest that the c-axis asymmetry reflects the relative significance of e-twinning versus intracrystalline slip.…”

Section: Penetrative Deformation In the Battleship Peak Area And Vertmentioning

confidence: 99%

“…12). The long axes of recrystallized grains in mylonites typically initiate parallel to the instantaneous stretching axis (ISA 1 ) and rotate during progressive shear, so grains that form the largest angle with respect to foliation should approximate the orientation of the ISA 1 (e.g., Law et al, 1984;Dell'Angelo and Tullis, 1989;Wallis, 1995;Spanos et al, 2015). In the 6 marble mylonite samples the maximum angle between grain shape orientation and foliation (not including outliers that are not within a continuous range of the mode orientation) ranges from 30° to 43°, with an average of 37° (excluding BP-201, which does not have a strong calcite grain shape-preferred orientation, the average is 38°; Table DR5).…”

Section: Penetrative Deformation In the Battleship Peak Area And Vertmentioning

confidence: 99%

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The role of calcite-rich metasedimentary mylonites in localizing detachment fault strain and influencing the structural evolution of the Buckskin-Rawhide metamorphic core complex, west-central Arizona

2018

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Although crystalline rocks dominate the footwall of the Buckskin-Rawhide detachment fault in west-central Arizona (USA), we estimate that thin (<1 to 100 m thick) calcite-rich metasedimentary mylonites were present along 25%-35% of the detachment fault, and in parts of the footwall they were continuous for ~30 km in the slip direction. New field observations, geochronology, and detailed microstructural data provide insight into the origin of these metasedimentary rocks and their role in the structural evolution of the detachment fault system. We propose that calc-mylonites along the Ives Peak footwall corrugation were derived from locally overturned Pennsylvanian-Permian strata that were buried to mid-crustal depths beneath a southeast-vergent Cretaceous thrust fault, which was reactivated in the Miocene by the parallel Buckskin detachment fault shear zone. In some areas these laterally persistent calc-mylonites were smeared out along the detachment fault during incisement into the crystalline footwall, forming a thin carapace of rheologically weak rocks structurally below the original weak zone. Metasedimentary mylonites consistently record top-to-the-northeast simple shear parallel to the detachment fault slip direction. Strain, synmylonitic veins, and paleostress recorded in these mylonites increase toward the detachment fault. Marble mylonites <1 m below the detachment fault preserve strong calcite crystallographic preferred orientations and lack cataclastic deformation that characterizes quartz-rich rocks along the detachment fault. In addition, unlike quartzofeldspathic mylonites, calc-mylonites typically lack extension via postmylonitic normal faults and associated horizontal axis rotation. Paleopiezometry and rheological modeling of the metasedimentary mylonites suggest that when quartzite layers were being sheared at ~100 MPa and 10 −13 to 10 −14 s −1 near the brittle-plastic transition, marble layers could have been strained ~100× faster at ~20 MPa. Detachment fault strain localized within the metasedimentary rocks, and the calcite marbles exerted significant control on the rheology of the footwall shear zone. This study highlights the important role that inherited weak zones may play in influencing the location, geometry, rheology, and style of deformation associated with detachment fault systems.

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Section: Penetrative Deformation In the Battleship Peak Area And Vertmentioning

confidence: 99%

Section: Penetrative Deformation In the Battleship Peak Area And Vertmentioning

confidence: 99%

The role of calcite-rich metasedimentary mylonites in localizing detachment fault strain and influencing the structural evolution of the Buckskin-Rawhide metamorphic core complex, west-central Arizona

2018

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“…Notably, this assumption has been extensively used to estimate kinematic vorticity in quartz tectonites (e.g., Weijermars, 1991Weijermars, , 1993Weijermars, , 1998Xypolias and Doutsos, 2001;Law et al, 2004;Zheng and Wang, 2005;Xypolias, 2009;Liang et al, 2015). Thus, it is reasonable to extend this approach to the analysis of calcite tectonites since the mechanism of formation of oblique foliation is similar to both rock types (Passchier, 1998;Spanos et al, 2015). Therefore, we suggest that the greatest recorded angle, δ, between the oblique grain shape fabric and the mylonitic foliation or shear plane can be used to estimates the kinematic vorticity (Fig.…”

Section: Kinematic Vorticitymentioning

confidence: 97%

“…Kinematic vorticity estimates can also be obtained based on the assumption that the orientations of the long axes of recrystallized grains are parallel to the direction of the instantaneous stretching axis of flow (Wallis, 1995;Spanos et al, 2015;Fig. 10).…”

Section: Kinematic Vorticitymentioning

confidence: 99%

“…10). Lots of experimental studies have demonstrated that recrystallized grains within an oblique grain shape fabric, and their long axes in a fixed orientation which progressively rotate towards parallelism with the shear plane (Dell'Angelo and Tullis, 1989;Ree, 1991;Herwegh and Handy, 1998;Spanos et al, 2015). Notably, this assumption has been extensively used to estimate kinematic vorticity in quartz tectonites (e.g., Weijermars, 1991Weijermars, , 1993Weijermars, , 1998Xypolias and Doutsos, 2001;Law et al, 2004;Zheng and Wang, 2005;Xypolias, 2009;Liang et al, 2015).…”

Section: Kinematic Vorticitymentioning

confidence: 99%

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Macro‐and Microstructural, Textural Fabrics and Deformation Mechanism of Calcite Mylonites from Xar Moron‐Changchun Dextral Shear Zone, Northeast China

Liang

Liu

Zheng

et al. 2019

Acta Geologica Sinica (Eng)

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The calcite mylonites in the Xar Moron‐Changchun shear zone show a significance dextral shearing characteristics. The asymmetric (σ‐structure) calcite/quartz grains or aggregates, asymmetry of calcite c‐axes fabric diagrams and the oblique foliation of recrystallized calcite grains correspond to a top‐to‐E shearing. Mineral deformation behaviors, twin morphology, C‐axis EBSD fabrics, and quartz grain size‐frequency diagrams demonstrate that the ductile shear zone was developed under conditions of greenschist facies, with the range of deformation temperatures from 200 to 300°C. These subgrains of host grains and surrounding recrystallized grains, strong undulose extinction, and slightly curved grain boundaries are probably results of intracrystalline deformation and dynamic recrystallization implying that the deformation took place within the dislocation‐creep regime at shallow crustal levels. The calculated paleo‐strain rates are between 10−7.87 s−1 and 10−11.49 s−1 with differential stresses of 32.63–63.94 MPa lying at the higher bound of typical strain rates in shear zones at crustal levels, and may indicate a relatively rapid deformation. The S‐L‐calcite tectonites have undergone a component of uplift which led to subhorizontal lifting in an already non‐coaxial compressional deformation regime with a bulk pure shear‐dominated general shear. This E‐W large‐scale dextral strike‐slip movement is a consequence of the eastward extrusion of the Xing'an‐Mongolian Orogenic Belt, and results from far‐field forces associated with Late Triassic convergence domains after the final closure of the Paleo‐Asian Ocean.

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Vorticity analysis in the Zagros orogen, Shiraz area, Iran

Sarkarinejad

Heibati

2016

Int J Earth Sci (Geol Rundsch)

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Vorticity analysis in calcite tectonites: An example from the Attico-Cycladic massif (Attica, Greece)

Cited by 15 publications

References 64 publications

The role of calcite-rich metasedimentary mylonites in localizing detachment fault strain and influencing the structural evolution of the Buckskin-Rawhide metamorphic core complex, west-central Arizona

The role of calcite-rich metasedimentary mylonites in localizing detachment fault strain and influencing the structural evolution of the Buckskin-Rawhide metamorphic core complex, west-central Arizona

Macro‐and Microstructural, Textural Fabrics and Deformation Mechanism of Calcite Mylonites from Xar Moron‐Changchun Dextral Shear Zone, Northeast China

Vorticity analysis in the Zagros orogen, Shiraz area, Iran

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