Spatial slip behavior of large strike‐slip fault belts: Implications for the Holocene slip rates of the eastern termination of the North Anatolian Fault, Turkey

Abstract

We present new data on Holocene slip rates for the eastern end of the North Anatolian Fault (NAF) by using the optically stimulated luminescence ages of the offset terrace deposits at two sites, where a total of four displaced landforms was studied. Each offset feature was analyzed independently, and three different assumptions were made for all the offsets, depending on whether the age of the upper tread (upper tread reconstruction), the lower tread (lower tread reconstruction), or all bounding surfaces (intermediate solution) were used in dating of the terrace risers. The deflected geometry of the risers strongly suggests the use of either the intermediate solution or the upper tread reconstruction. The joint slip rate distributions for the upper tread reconstructions and the intermediate solutions were modeled as 13.0 + 1.8 / −1.4 and 14.3 + 5.8 / −2.4 mm/yr (2σ), respectively. Although the intermediate solution covers the full range of ages for the measured displacements, the curved geometry of the terrace risers suggests that the initiations of the riser offsets are most probably close to the abandonment ages of the upper terrace treads. Therefore, we accepted the joint slip rate of the intermediate solution but suggested that the average rate for the main displacement zone of the eastern NAF should be close to its lower limits. This slower rate with respect to previous estimates suggests that the total deformation is not only accommodated on the main displacement zone but is also distributed along the secondary faults to the south of the easternmost segments of the NAF.

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

“…These curvilinear faults initiate from the NAFZ at beginning of the Experiment 3, propagate into the wedge and terminate around the EAFZ. Development of these faults support the idea, which depend upon paleoseismological (Sançar & Akyüz, 2014) and slip-rate studies (Zabcı et al, 2015a), non-homogeneous deformation in the easternmost part of the NAFZ, close the KTJ, is due to distribution of total strain between the main deformation zone and secondary faults. Furthermore, to explain the initiation and development of these faults by using their geometry and sense of motion passive wedge-shaped Prandtl cell model of Varnes (1962) is more appropriate to explain the overall, regional fault pattern than the previously proposed active Prandtl cell model by (Şengör, 1979; Şengör et al, 1985).…”

“…Considering the age of the NAFZ and EAFZ, although there is no age determination the VFZ, we assume that they have already been formed in Plio-Quaternary and their orientation, sense of motion and velocity of NAFZ and EAFZ are known. Furthermore, not only previous studies (Sançar, 2014;Sançar et al, 2011b;Zabcı et al, 2015a) but also the geology of the Karlıova region ( Figure 5) show that the tectonic structures between the NAFZ and EAFZ in the vicinity of the KTJ have already been formed and active during the Plio-Quaternary. In order to understand causal relationship between the main fault zones (the NAFZ and EAFZ) and tectonic structures of the Karlıova region, we organize the initial orientation of the plate boundaries (basement faults) in accord with the Plio-Quaternary geometry of the triple junction components (Figure 8 (a)): The boundary between the Eurasian Plate and the Anatolian Scholle (future NAFZ) is oriented N70°W, as is the boundary between the Eurasian Plate and the Arabian Plate (future VFZ).…”

“…This non-homogeneous behavior may be due to the (a) the release of energy through small and frequent earthquakes, such as the 2005 Karlıova earthquakes (Emre, Özalp, Yildirim, Özaksoy, & Doğan, 2005), and/or (b) the distribution of total strain between the main deformation zone and secondary faults (Sançar & Akyüz, 2014). The geologic slip-rate study, which claims that the main branch of the NAFZ only takes up to 55-75% (Zabcı et al, 2015a) of the total rate of about 20 mm/yr (Cavalié & Jónsson, 2014;Walters, Parsons, & Wright, 2014) and the rest of the deformation is taken up by secondary faults.…”

“…However, the secondary faulting around the KTJ and the VFZ have been used to explain the deformation around the KTJ and put forward some regional result (Barka & Gülen, 1988). Furthermore, the strong relationship has been established between the non-homogeneous behavior of eastern part of the NAFZ and the secondary faults (Sançar et al, 2015;Zabcı et al, 2015a). In this regard, the region close to KTJ has a key spatial position to understand how deformation initiate and develop between the main fault zones and evaluate the proposed ideas about not only around the KTJ but also eastern part of the 'Ova' province.…”

“…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).…”