The output (.pmag) file including details of paleomagnetic analysis performed in this study can be evaluated and visualized in the available modules of the online portal of Paleomagnetism.org.
The west Anatolian extensional province is dominantly shaped by an E–W-trending graben-forming high-angle normal faults. However, there are some studies revealing the presence of a number of NE-trending strike-slip faults deforming the western Anatolia crust onshore and offsore. The Izmir Bay and the surrounding area is located at the NE-trending strike-slip dominated zone of weakness known as the Izmir-Balikesir Transfer Zone forming the western end of the west Anatolian extensional province. The Izmir Bay is a marine basin that controlled by NE, NW, N-S and E-W trending active faults. The bay of Izmir is topographically divided into an E-trending inner bay and an NW-trending outer bay. The southern sector of the inner bay is bounded by Izmir Fault which is made up of two main segments trending approximately in E-W. According to field studies, the Izmir Fault is an oblique-slip normal fault dipping to the north. The northern sector of the inner bay is bounded by Kar siyaka Fault which is antithetic to the Izmir Fault. Kar siyaka Fault in this section has a characteristic of oblique-slip normal fault dipping to the south. The NE-trending Seferihisar Fault, which is approximately developed normal to the Izmir Fault is approximately 30 km long on the land. Morphological, geological and seismological evidences suggest that the northern segment of the Seferihisar fault has been activated during Holocene time. The fault is a dextral strike-slip fault with oblique-slip movement. The fault trends in N20E at the southern part where it cuts the Upper Cretaceous Bornova Flysch and Quaternary alluvium. Towards the north, the strike of the fault changes to N40-50E and it gets connected with the Izmir Fault. Within the excavated trenches on the fault segments mapped in 1/1000 scale, it is established that the strike-slip fault (Seferihisar Fault) is transformed by bending into the normal fault (Izmir Fault). Kinematic analysis carried out at 9 stations suggest that the faults have controlled by an N-S extensional direction associated with E-W contraction. The data support that the kinematically linked Izmir Fault, Seferihisar Fault and Kar siyaka Fault have been contributed to the opening of the inner bay of under the control of the transtensional forces.
The Quaternary period on the western coast of Turkey is studied using sedimentological features and geochronological age data of the Söke-Milet Basin (SMB), which is a subsidiary to the Büyük Menderes Graben (BMG). Here, for the first time, we geochronologically document the Early Pleistocene shallow marine fan-deltaic succession in the Fevzipaşa Formation (basin-fill unit of the SMB), 15 km inland of the current Aegean coast and 150 m above current sea level. The formation outcrops at the western end of the BMG. It comprises an alluvial fan to freshwater carbonate, shallow marine fan-deltaic and alluvial fan depositional packages separated by intrabasinal unconformities. Based on conventional sedimentary data, seven different facies associations (FA) have been distinguished in the Fevzipaşa Formation: (FA 1) hyperconcentrated flow-generated lower alluvial fan deposits, (FA 2) freshwater lacustrine carbonate deposits, (FA 3) prodelta deposits, (FA 4) shallow marine fan-delta slope deposits, (FA 5) nearshore sandy mouth-bar-type fan-delta front deposits, (FA 6) alluvial fan-delta top deposits and (FA 7) hyperconcentrated flow-generated upper alluvial fan deposits. The shallow marine facies above the lower alluvial fan deposits, considered in conjunction with stratigraphical observations and geochronological and paleontological age data, suggest that a late Early Pleistocene transgression affected the Aegean region.
Cenozoic convergence between the Eurasian and African plates and concurrent slab roll-back processes have produced a progressive extension in back-arc areas, such as the Aegean region and western Anatolia. There is still a long-standing controversy as to whether this was a continuous or stepwise process. To shed light on this controversy and on the driving mechanism of regional extension, we present palaeomagnetic and geochronological results from the Söke Basin located at the southeastern rim of the İzmir–Balıkesir Transfer Zone. Our improved geochronology shows that volcanic activity in the region occurred between 11.66 and 12.85 Ma. Middle to late Miocene palaeomagnetic data for the Söke Basin show a c. 23° clockwise rotation, whereas early Miocene data show a c. 28° counterclockwise rotation. The primary nature of the magnetization is indicated by a positive tilt test. The resulting c. 51° counterclockwise rotations during the middle Miocene signify a major tectonic reorganization, during a period when an interruption of exhumation of metamorphic massifs has been reported. We suggest that the İzmir–Balıkesir Transfer Zone is the main driver of the reorganization in the region. The regional fingerprint of this tectonic reorganization coincides with the acceleration of trench retreat and illustrates the surface impact of tearing of the Hellenic slab. Supplementary material: Details of 40 Ar/ 39 Ar analysis including heating steps and the output (.pmag) file including details of paleomagnetic analysis performed in this study are available at https://doi.org/10.6084/m9.figshare.c.3690871
Izmir ili ve cevresi Izmir-Balikesir Transfer Zonu olarak bilinen dogrultu-atimli faylarca baskin bir zayiflik zonu icinde yer alir. Bu zonun son aktivitesi 17-20 Ekim 2005-Sigacik korfezi depremleriyle kanitlanmistir. Bu calismada Sigacik Korfezi depremlerinin sismo-jeomorfolojik ozelliklerinin bolgedeki aktif faylar ve gerilme dagilimlariyla iliskisi tartisilacaktir. Ana soklari Sigacik Korfezi’nde 17-20 Ekim 2005 tarihlerinde olan orta buyuklukteki uc deprem (17 Ekim 2005, saat: 05.45, buyukluk Mw=5.4, 17 ekim 2005, saat: 09.46, buyukluk Mw=5.8 ve 20 Ekim 2005, saat: 21.40, buyukluk Mw=5.9) Sigacik Korfezi’nin kara kisminda sismik sok sirasinda gelismis tortullasmayla yasit bicim degis tirme yapilarinin (sismitlerin) olusmasina neden olmustur. Bu yapilar depremlerden hemen sonra haritalanmis ve sismo-jeomorfolojik ozelliklerine gore degerlendirilmistir. Tortullasmayla yasit bicim degistirme yapilari Urla Havzasi guneyindeki Demircili Koyu ve Yumlu Ciftligi cevresinde tespit edilmistir. Bu yapilar karasal tortullarla girik olan cakilli ve kumlu plaj cokellerinde gelismistir. Sismitler KD-GB ve D-B dogrultulu catlaklar ile sivilasmayla olusmus kum volkanlarindan yapilidir. KD-GB dogrultulu catlaklar onlarca cm ile birkac m uzunlugundadir ve yerel olarak kaynasmis geometri sunan kademeli bir sekle sahiptir. Bunlar ana fay segmentleri ile uyumlu olarak K40-70 D dogrultusunda uzanir. D-B dogrultulu kiri klar ise, Sigacik Korfezi’nin kiyi cizgisine paraleldir ve 8 cm’ye ulasan egim atim sunar. Yumlu ciftliginde, sismik sarsilma nedeniyle KKD dogrultusunda kilcal bir catlak olusmustur. Bununla beraber, Gulbahce Korfezi’nin bati kenari uzerindeki fayin sicrama alaninda (stepover) da kucuk olcekli kitle hareketleri saptanmistir. Tortullasmayla yasit bicim degistirme yapilari sismik sarsilmaya atfedilmesine ragmen, KD/KB dogrultu atimli faylar ve D-B oblik atimli faylarla sekillenmis olan tektonik catiyla da zamansal ve alansal anlamda yakin bir iliskiye sahiptir. Izmir depremlerinin ana ve artci soklarinin negatif bir cicek yapisi sunan bu tektonik catiyla uyumluluk sunmasi bunun en belirgin kanitidir. Bu cicek yapisi Kuvaterner yasli Urla Havzasi ni sekillendiren ve yukari dogru-iraksayan dogrultu atimli fay kollariyla baskin bir fay zonuyla karakteristiktir.
Calisma, Gemliklin guneyinde yeralan Alt Tersiyer kayalarim konu eder. Bes kaya birimi ayirdedilmistir, alttan uste* Seckoy camurtasi-gakiltasi birimi, Durdane gamurtasi-cakutasi- kumtagi birimi, Hisartepe kirectasi birimi ve Gengali kumtasi-gamurtasi birimi* Segkoy birimi, camurtaslarmdan ve volkanoklastik cakutaslarindan yapilidir, Diirdane birimi, egemen olarak kirmmmei, kahverengimsi camurtasi ve kumtaslarmdan olusur; yersel olarak cakiltasi arakatkilari icerir. Kurtul kalkerli camurtasi birimi sarimsi, beyazimsi renklidir, Hisartepe kirectap birimi, beyazimsi renklidir. Hisartepe kirectasi birimi, beya« zimsi, biyoklast kapsamli kiregta§larmdan ve kalkerli gamurtasi arakatkilarmdan yapilidir. Kirectasi Eosen Basi yaslidir. Gengali birimi, ince katmanli kumtaslarini ve sarimsi, yesilimsi, kirmmms! camurtaslarmi nobetlesmeli olarak icerir. Birimler genellikle uyumlu olarak birbirlerini Merler, Tersiyer kesitinin toplam kaJiniigi en m 630 metre dir. Sedimantoloji ve Paleontoloji ozellikleri bu birimlerin kiyi bolgesi cokelme alaninda olustuklarini yansitir,
