Seismic history of western Anatolia during the last 16 kyr determined by cosmogenic 36Cl dating.

Western Anatolia is one of the most seismically active regions worldwide. To date, the paleoseismic history of many major faults, in terms of recurrence intervals of destructive earthquakes, their magnitude, displacement, and slip rates is poorly understood. Regional crustal extension has produced major horst-graben systems bounded by kilometer-scale normal faults locally in carbonates, along which vertical crustal displacements occurred. In this study, we explore the seismic history of western Anatolia using 36Cl exposure dating through study of well-preserved carbonate normal fault scarps. To accomplish this, 36Cl concentrations in 214 samples from fault plane transects on the Rahmiye and Ören fault scarps were measured and compared with existing 36Cl measurements of 370 samples on five fault scraps in western Anatolia. At least 20 seismic events have been reconstructed over the past 16 kyr. The age correlation of the seismic events implies four phases of high seismic activity in western Anatolia, at around 2, 4, 6, and 8 ka. Slips are modeled ranging between 0.6 to 4.2 m per seismic event, but are probably the result of clustered earthquakes of maximum magnitude 6.5 to 7.1. While the average slip rates have values of 0.3 to 1.9 mm/yr, incremental slip rates of the faults range greater than 0.1 to 2.2 mm/yr, showing more activity mostly through late Holocene. Our finding reveals high capability of cosmogenic 36Cl dating to explore seismic behavior of active faults beyond the existing earthquake records. Supplementary Information The online version contains supplementary material available at 10.1186/s00015-022-00408-x

Field evidence for normal fault linkage and relay ramp evolution: the Krkaac Fault Zone, western Anatolia (Turkey)

Linking of normal faults forms at all scales as a relay ramp during growth stages and represents the most efficient way for faults to lengthen during their progressive formation. Here, I study the linking of normal faulting along the active Krkaac Fault Zone within the west Anatolian extensional system to reconstruct fault interaction in time and space using both field- and computer-based data. I find that (i) connecting of the relay zone/ramp occurred with two breaching faults of different generations and that (ii) the propagation was facilitated by the presence of pre-existing structures, inherited from the zmir-Balkesir transfer zone. Hence, the linkage cannot be compared directly to a simple fault growth model. Therefore, I propose a combined scenario of both hangingwall and footwall fault propagation mechanisms that explain the present-day geometry of the composite fault line. The computer-based analyses show that the approximate slip rate is 0.38mm/year during the Quaternary, and a NE-SW-directed extension is mainly responsible for the recent faulting along the Krkaac Fault Zone. The proposed structural scenario also highlights the active fault termination and should be considered in future seismic hazard assessments for the region that includes densely populated settlements

İzmir-Balıkesir transfer zonunun jeolojik evrimi: Batı Anadolu'daki genişleme tektoniğini yeniden organize eden kıtasal ölçekte bir yapı

Bu tez, Ege Genişleme Sistemindeki Menderes Çekirdek Kompleksi ile Kikladlar arasındaki farklı deformasyonu karşılayan ve kabuksal ölçekli bir makaslama zonu olarak tanımlanan İzmir-Balıkesir Transfer Zonu?nun yapısal önemini tanımlamayı amaçlar. Bu çalışmada, İBTZ içindeki Miyosen-Kuvaterner birimleri 1/25.000 ölçeğinde haritalanmış ve birimlerden stratigrafik, yapısal, jeomorfolojik, paleomanyetik ve jeokronolojik veriler elde edilmiştir. Veriler İBTZ?nin transtansiyonal bir makaslama zonu olduğunu ve Neojen öncesi temel kayaları, Neojen volkanosedimanter istifleri ve Pliyo-Kuvaterner birimlerini deforme ettiğini göstermiştir. Yapısal ve kinematik verilere göre, İBTZ?de Geç Senozoyik?te üç deformasyon evresi tanımlanmıştır. Miyosen dönemine karşılık gelen ilk evrede K-G genişleme ve D-B sıkışma sonucunda gelişen doğrultu atımlı faylarca baskındır. Bu evrede KD-GB uzanımlı Miyosen volkanosedimanter havzaların oluşumu gerçekleşmiştir. İkinci evre doğrultu atım-baskın transtansiyondan genişleme-baskın transtansiyona dönüşen tektonizmayla ilişkilidir. Bu evre olasılıkla Erken Pliyosen?deki orta Kiklad çizgiselliğinin aktivitesini yitirmesi ve Menderes çekirdek kompleksinin orta bölümünün en son yüzeylemesiyle eşyaşlıdır. Son evre KB-GD sol yönlü doğrultu atımlı fay, KD-GB sağ yönlü doğrultu atımlı fay ve D-B doğrultulu normal fayların birlikte çalışmasıyla karakteristiktir. Son evrede İBTZ parçalanarak daha dar bir makaslama zonuna dönüşmüştür. Yeni paleomagnetik veriler İBTZ?nin saat ibresinin tersi yönünde rijit bloklar şeklinde rotasyona uğrayan Menderes Çekirdek Kompleksi ve Kikladları ayıran ve zon içinde saatibresi yönünde rotasyonların geliştiği bir makaslama zonu olduğunu göstermektedir. Tüm verilere göre, İBTZ Anadolu levhası altındaki yitim zonundaki bir yırtığın yüzeye yansımış şekli olarak yorumlanabilir. This thesis attempts to expose the structural implication of a crustal scale zone of weakness, the İzmir?Balıkesir transfer zone (İBTZ) which is a recently recognized as strike-slip dominated shear zone that accommodates the differential deformation between the Cycladic and Menderes core complexes within the Aegean Extensional System. Here, I present new stratigraphic, structural, paleomagnetic, geochronologic and kinematic data and 1/25,000 scale mapping of Miocene to Recent rock units within the İBTZ. The results point out that the İBTZ is a transtensional brittle shear zone that deforms the pre-Neogene basement rock units, the early-middle Miocene volcano-sedimentary units and the Plio?Quaternary continental units. The analysis of large-scale structures and fault kinematic data indicate that three different deformation phases prevailed in the İBTZ during the late Cenozoic. The first phase (Phase 1) is characterized by N?S directed extension and E?W contraction that gave way to the development of strike-slip faults with normal components and likely took place during the early (?) to late Miocene. This transtensional phase, forming the volcano-sedimentary basin was overprinted by the second phase (Phase 2) which is characterized by variable extension and contraction directions indicating wrench-to extension-dominated transtension. The structures related to Phase 2 are observed all around the İzmir Bay and indicate a distributed nature of the deformation that probably took place during the early Pliocene, coeval with the end of the activity of the mid-Cycladic lineament and the last exhumation of the central Menderes core complex. The latest deformation phase (Phase 3) is characterized by an association of NW?SE trending left-lateral and NE?SW trending right-lateral strike-slip faults and E?W trending normal faults forming extensional deformation. During Phase 3, the İBTZ evolved from a wider shear zone into a relatively narrow discrete fault zone by the late Pliocene, during which the strike-slip and extensional deformation were completely decoupled from each other. With respect to new paleomagnetic data, İBTZ is a clockwise rotated structural shear zone that separated two counterclockwise rotated rigid blocks; the Menderes and Cycladic complexes, and can be interpreted as the surface reflection of the teared part of the subduction beneath the Anatolian plate

A first record of a strike-slip basin in western Anatolia and its tectonic implication: The Cumaovasi basin

The Cumaovasi basin, formerly known as the Cubukludag Graben, is located at the western end of Gediz and Kucuk Menderes grabens in the west Anatolian extensional province. It is 5-17-km wide and 35-km-long, NNE-SSW-trending, asymmetric basin that was formed under the control of strike-slip and oblique-slip normal faults