Neotectonics and seismicity of Erzurum pull-apart basin, East Turkey

Abstract

The study area is the Erzurum pull-apart basin located in the East Anatolian Tectonic Block (EATB), which is under the control of a strike-slip neotectonic regime since the beginning of Quaternary. The Quaternary Erzurum pull-apart basin is an about 1–30 km wide, 90 km long and actively growing strike-slip depression. It is bounded by the Erzurum–Dumlu sinistral strike-slip fault zone to the east-southeast, by the Askale sinistral strike-slip fault zone to the north-northwest, and by the Basköy–Kandilli reverse fault zone and the N–S-trending Ilica oblique-slip normal fault set to the west. The Erzurum pull-apart basin was evolved by the deformation and subdivision of an E–W-trending older intermontane basin. The new basin has a 0.5 km thick, flat-lying (undeformed) and uconsolidated fill, which overlies, with an angular unconformitry, the deformed (folded and faulted) basement rocks of pre-Quaternary age. Basin fill consists of coarser-grained marginal facies (fault terrace, fan, fan-apron and superimposed fan deposits) and finer-grained depocentral facies represented by flood plain to organic material-rich marsh deposits. All gradations are seen among these lithofacies. The seismicity of the Erzurum pull-apart basin is quite high. The magnitude of the peak earthquake to be sourced from the active faults (e.g., the Erzurum fault) is about Mw = 7.0. This was proved by both the historical and recent earthquakes. Numerous settlements in the size of a large city (e.g., Erzurum), county, town and small villages with a total population of over 766,000 are located in and along the active fault-bounded margins of the Erzurum pull-apart basin. They are under the threat of destructive earthquakes to be sourced from the margin-boundary faults. Therefore, based on both the active fault parameters and the water-saturated basin fill, a large-scale earthquake hazard map has to be prepared. This map has to be used in both the earthquake hazard to risk analyses and the redesign of city planning and all type of constructions in Erzurum and other settlements in this region.

The Local Earthquake Tomography of Erzurum (Turkey) Geothermal Area

“…The Erzurum pull-apart basin is mainly developed by the deformation and subdivision of an E-W-trending paleo-tectonic unit, during the Quaternary strike-slip neotectonic period. It is located in the East Anatolian tectonic block, which has been controlled by a strike-slip neo-tectonic regime since the early Quaternary period (Kocyigit and Canoglu 2017). The Quaternary Erzurum pull-apart basin is an approximately 90 km long, 30 km wide, actively developing strike-slip depression.…”

“…Previous studies such as Baris et al (2005), Ozer and Polat (2017a, b), Ozer et al (2018) indicate that geothermal fluids are born in the crust by thermal conduction, particularly in volcanic and tectonically active areas. Furthermore, Kocyigit and Canoglu (2017) claimed that the Erzurum pull-apart basin is also a geothermal field, but this aspect of the basin has not been studied yet (Fig. 1).…”

“…Several studies have been conducted in the study area within the earth sciences. The geological structure and tectonic evolution of Erzurum region and its surroundings have been mainly investigated by Keskin et al (1998), Yarbasi and Kalkan (2009), Kocyigit and Canoglu (2017). Moreover, there are some attempts associated with geothermal potential (Bektas et al 2007;Gulec and Hilton 2016), geochemical (Bayraktutan et al 1996;Keskin e al.…”

“…The most prominent results were produced by the Eastern Turkey Seismic Experiment (ETSE) project in the east-southeastern edge of the Erzurum pull-apart basin. The AFZ is a 6 km wide, 140 km long and extends along the NE-trending sinistral strike-slip fault zone (Kocyigit and Canoglu 2017) (Fig. 2).…”

The Ground-Motion Attenuation Comparison: A case study for the 2017/05/11 Askale earthquake (Mw4.7)

“…Erzurum is located on the Eastern Anatolian Tectonic Block [1][2]. Destructive earthquakes occurred in and around Erzurum in both historical and instrumental periods.…”