Distributed transpressive continental deformation: The Varto Fault Zone, eastern Turkey

Sançar, Taylan; Zabcı, Cengiz; Akyüz, H. Serdar; Sunal, Gürsel; Villa, Igor M.

doi:10.1016/j.tecto.2015.08.018

Cited by 17 publications

(22 citation statements)

References 28 publications

(26 reference statements)

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“…1). The VFZ extends for over 50 km, strikes N105°E-N120°E and can be subdivided into six fault segments (Sançar et al, 2015). The Varto Fault (VF, Fig.…”

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

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Numerical modelling of triple-junction tectonics at Karlıova, Eastern Turkey, with implications for regional magma transport

Karaoğlu

Browning

Bazargan

et al. 2016

Earth and Planetary Science Letters

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Few places on Earth are as tectonically active as the Karlıova region of eastern Turkey. In this region, complex interactions between the Arabian, Eurasian and Anatolian plates occur at the Karlıova Triple Junction (KTJ). The relationship between tectonics and magma propagation in triple-junction tectonic settings is poorly understood. Here we present new field and numerical results on the mechanism of magma propagation at the KTJ. We explore the effects of crustal heterogeneity and anisotropy, in particular the geometry and mechanical properties of many faults and layers, on magma propagation paths under a variety of tectonic loads. We propose that two major volcanic centres in the area, the Turnadağ volcano and the Varto caldera, are both fed by comparatively shallow magma chambers at depths of about 8 km, which, in turn, are fed by a single, much larger and deeper reservoir at about 15-18 km depth. By contrast, the nearby Özenç volcanic area is fed directly by the deeper reservoir. We present a series of two-dimensional and three-dimensional numerical models showing that the present tectonic stresses encourage magma-chamber rupture and dyke injection. The results show that inversion tectonics encourages the formation of magma paths as potential feeder dykes. Our three-dimensional models allow us to explore the local stresses induced by complex loading conditions at the Karlıova triple junction, using an approach that can in future be applied to other similar tectonic regions. The numerical results indicate a great complexity in the potential magma (dyke) paths, resulting from local stresses generated by interaction between mechanical layers, major faults, and magma chambers. In particular, the results suggest three main controls on magma path formation and, eventual eruptions, at KTJ: (1) the geometry and attitude of the associated faults; (2) the heterogeneity and anisotropic of the crust; and (3) mechanical (stress) interactions between deep and shallow magma chambers.

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“…1). The VFZ extends for over 50 km, strikes N105°E-N120°E and can be subdivided into six fault segments (Sançar et al, 2015). The Varto Fault (VF, Fig.…”

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

“…2) show distinct volcanic facies, and also certain geochemical characteristics (e.g. Buket and Temel, 1998;Hubert-Ferrari et al, 2009;Sançar et al, 2015).…”

Section: Geologic and Tectonic Settingmentioning

confidence: 99%

Numerical modelling of triple-junction tectonics at Karlıova, Eastern Turkey, with implications for regional magma transport

Karaoğlu

Browning

Bazargan

et al. 2016

Earth and Planetary Science Letters

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“…The VFZ extends from the KTJ for about 30 km to the ESE along a widely-distributed deformation zone with a maximum width of 12 km (Sançar et al, 2015) (Figure 2). The interpretation of the structures in the VFZ is controversially discussed and several models have been proposed to explain the mechanical behavior and/or initiation of the VFZ: (a) as the eastern continuation of the NAF (Gürboğa, 2016;Ketin, 1969Ketin, , 1976).…”

Section: The Varto Fault Zone (Vfz)mentioning

confidence: 99%

“…The Anatolian Scholle, which represents one of the most outstanding intraplate regions in the eastern Mediterranean region, is bounded by two large strike-slip fault zones, the North Anatolian Fault Zone (NAFZ) and the East Anatolian Fault Zone (EAFZ), marking the northern and southeastern boundaries (Şengör, 1980; Şengör et al, 1985), respectively (Figure 1(a)). The boundary between the Eurasian and Arabian plate is distributed in a wide zone, mostly represented by discrete structures of a long-lived transpressional setting, named the Varto Fault Zone (VFZ) ( Figure 2) (Sançar, Zabcı, Akyüz, Sunal, & Villa, 2015). The discussions on the stationary (Sançar et al, 2015;Şengör, 1979Şengör et al, 1985;Zabcı, Sançar, Akyüz, & Kıyak, 2015a) or migrating (Barka & Gülen, 1988;Hubert-Ferrari et al, 2009;Westaway & Arger, 2001;Westaway, Demir, & Seyrek, 2008) nature of the continental KTJ and the surrounding structural complexity make this region of particular interest.…”

Section: Introductionmentioning

confidence: 99%

“…The boundary between the Eurasian and Arabian plate is distributed in a wide zone, mostly represented by discrete structures of a long-lived transpressional setting, named the Varto Fault Zone (VFZ) ( Figure 2) (Sançar, Zabcı, Akyüz, Sunal, & Villa, 2015). The discussions on the stationary (Sançar et al, 2015;Şengör, 1979Şengör et al, 1985;Zabcı, Sançar, Akyüz, & Kıyak, 2015a) or migrating (Barka & Gülen, 1988;Hubert-Ferrari et al, 2009;Westaway & Arger, 2001;Westaway, Demir, & Seyrek, 2008) nature of the continental KTJ and the surrounding structural complexity make this region of particular interest. Although recent publications discuss the faulting around the VFZ in details, to the east of the KTJ, (Gürboğa, 2016;Hubert-Ferrari et al, 2009;Karaoğlu, Selçuk, & Gudmundsson, 2017;Sançar et al, 2015) and propose different faulting mechanisms, they provide less information on the distribution of faults and their mechanics for the region west of around the KTJ (Gürboğa, 2016;Hubert-Ferrari, Armijo, King, Meyer, & Barka, 2002;Karaoğlu et al, 2017;Tutkun & Hancock, 1990).…”

Section: Introductionmentioning

confidence: 99%

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Mechanics of plio-quaternary faulting around the Karliova triple junction: implications for the deformation of Eastern part of the AnatolianScholle

et al. 2018

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The intersection of the Eurasian and Arabian plates and the smaller Anatolian Scholle created the Karlıova Triple Junction (KTJ) in eastern Turkey. In this study, we present analogue model experiments for this region and compare the results with our field observations and data from remote sensing imagery. Our comparison suggests that the sense of slip along curvilinear faults at the west of the KTJ changes along strike moving away from the principal displacement zones, from strike-slip to oblique normal and then to pure normal slip. Although, the active Prandtl cell model has been proposed to explain the overall regional fault pattern at eastern part of the Anatolian Scholle, the map view orientation of the secondary faults within the Karlıova wedge and performed analogue modelling results suggest that the passive wedgeshaped Prandtl cell model with a normal dip-slip component along slip lines is more appropriate in order to explain not only deformation pattern around the KTJ but also internal deformation of eastern part of the Anatolia. Moreover, these faults accumulate the significant amount of deformation that causes to the irregular earthquake behavior and the relatively lower geologic slip-rates along the main fault branch of boundary faults around the KTJ.

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Depths of magma chambers at three volcanic provinces in the Karlıova region of Eastern Turkey

et al. 2018

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The size of a volcanic eruption, and thus the associated potential hazards, depends partly on the depth, geometry, and size of the source magma chamber. To estimate magma chamber depths and sizes, we apply a newly developed analytical method, based on the aspect ratio (length/thickness) of dikes, to three volcanoes in the Karlıova region of Eastern Turkey, namely Turnadağ, Varto, and Özenç. The results indicate that the depths of the source chambers are between 2 and 4 km at Turnadağ, 2 to 5 km at Varto, both of which are located in transtensional tectonic regimes, but from 22 to 27 km at Özenç, which is located in a convergent tectonic regime. A similar reservoir depth at Özenç is indicated by seismic tomography, and this data also suggests that the reservoir is laterally continuous for more than 40 km. The large volume of ignimbrites (>40 km 3) associated with Varto, a collapse caldera, indicates that caldera subsidence may have maintained the excess magmatic pressure (through tectonic forcing) in the chamber over a longer time than during normal pyroclastic eruptions. The dike aspect ratios further indicate magmatic overpressures of 13-21 MPa for Varto, 13-17 MPa for Turnadağ, and 26-31 MPa for Özenç. The combined results from seismic tomography, analytical models and magma compositions indicate that both Turnadağ and Varto volcanoes, which are typical stratovolcanoes composed of mostly intermediate, and more rarely, acidic magmas, were fed by two very shallow and comparatively small magma chambers (2-5 km depth). Whereas less evolved magmas were erupted from Özenç, which hosts predominantly basaltic and intermediate lavas and dikes that were fed by a deep reservoir at 22-27 km depth. Our tomographic models show that none of the volcanoes are located directly over the centre of a deep magma reservoir. Our data also indicates that the magma in the reservoir has migrated between 34 and 40 km in a right lateral motion (to the east) below Varto and Turnadağ, respectively, and 23 km in a left lateral motion (to the west) at Özenç over the past 3 Ma. This lateral propagation of magma can be explained by tectonic escape of the Anatolian block to the west through the Northern Anatolian Fault and the Varto Fault Zone over the last 6 Ma.

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Distributed transpressive continental deformation: The Varto Fault Zone, eastern Turkey

Cited by 17 publications

References 28 publications

Numerical modelling of triple-junction tectonics at Karlıova, Eastern Turkey, with implications for regional magma transport

Numerical modelling of triple-junction tectonics at Karlıova, Eastern Turkey, with implications for regional magma transport

Mechanics of plio-quaternary faulting around the Karliova triple junction: implications for the deformation of Eastern part of the AnatolianScholle

Depths of magma chambers at three volcanic provinces in the Karlıova region of Eastern Turkey

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