Plio-Quaternary kinematic development and paleostress pattern of the Edremit Basin, western Turkey (original) (raw)
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Geodinamica Acta, 2016
The Edremit Fault Zone (EFZ) forms one of the southern segments of the North Anatolian Fault Zone (NAFZ) at the northern margin of the Edremit Gulf (Biga Peninsula, South Marmara Region, Turkey). Stratigraphic, structural and kinematic results indicate that basinward younging of the fault zone, in terms of a rolling-hinge mechanism, has resulted in at least three discrete Miocene to Holocene deformational phases: the oldest one (Phase 1) directly related to the inactive Kazdağ Detachment Fault, which was formed under N-S trending pure extension; Phase 2 is characterised by a strike-slip stress condition, probably related to the progression of the NAFZ towards the Edremit area in the Plio-Quaternary; and Phase 3 is represented by the high-angle normal faulting, which is directly interrelated with the last movement of the EFZ. Our palaeoseismic studies on the EFZ revealed the occurrence of three past surface rupture events; the first one occurred before 13178 BC, a penultimate event that may correspond to either the 160 AD or 253 AD historical earthquakes, and the youngest one can be associated with the 6 October 1944 earthquake (M w = 6.8). These palaeoseismic data indicate that there is no systematic earthquake recurrence period on the EFZ.
The East Anatolian Fault: geometry, segmentation and jog characteristics
Geological Society, London, Special Publications, 2013
A detailed account is given of the fault geometry and segment structure of the East Anatolian Fault Zone as a whole based on mapping of active faults, supported by available seismological and palaeoseismological data. We divide the East Anatolian Fault into two main strands: southern and northern. The main southern strand is c. 580 km long between Karlıova and Antakya, and connects with the Dead Sea Fault Zone and the Cyprus Arc via the Amik triple junction. The northern strand, termed the Sürgü–Misis Fault system, is c. 350 km long and connects with the Kyrenia–Misis Fault Zone beneath the Gulf of İskenderun. We infer that slip partitioning between the main and northern strands of the East Anatolian Fault accommodates 2/3 and 1/3 of the slip rate of the lateral motion between the Arabian and Anatolian plates, respectively in the Çelikhan–Adana–Antakya region. Taking account of the time elapsed from the latest events on the East Anatolian Fault, we suggest that the Pazarcık and Aman...
Tectonic evolution of the central part of the East Anatolian Fault Zone, Eastern Turkey
TURKISH JOURNAL OF EARTH SCIENCES, 2021
The Eastern Anatolian Fault Zone (EAFZ), having a prominent place in the tectonic evolution of the Eastern Mediterranean, is a structural element of tectonic indentor due to the convergence between the African-Arabian plates and the Eurasian Plate. This study investigates the central part of EAFZ between Doğanyol (Malatya) and Çelikhan (Adıyaman). The geometry of the fault and the morphotectonic structures were determined by the field studies. Moreover, fault-slip data are measured according to the fault planes along the deformation zone for paleostress analysis. The paleostress analysis revealed three deformation phases that developed from the Late Eocene to the present due to the convergence between the Arabian Plate and the Anatolian Block. The first deformation phase is characterized by NW-SE compressional stress between Late Eocene and Late Oligocene periods. The second deformation phase is related to N-S compressional stress from the Middle Miocene to Pliocene. The most recent deformation phase shows the strike-slip faulting under the NNE-SSW compressional stress from the Late Pliocene to the present. The EAFZ developed during the last phase of these deformation stages. In addition, elongated ridges parallel to the fault, sinistral offsets of drainage networks, linear valleys, and fault terraces observed along the segment show that the study area exhibits active tectonic morphology of the EAFZ. The distribution of seismic activity that occurred during and after the recent mainshock (24 January 2020, Sivrice-Doğanyol earthquake) is compatible with the geometry of the segment and confirms strongly the active tectonics of the segment.
Natural Hazards, 2021
The Northern Branch of the North Anatolian Fault System controls and deforms the Izmit Basin and the Sapanca Lake Basin in the study area. Unlike the Sapanca Lake Basin, the oblique normal faults with WNW-ESE trending with maximum length of 5 km in the south of the basin have contributed to the deformation process in the formation of Izmit Basin. The fault sets mainly incline to the north. The N-S width of the dextral strike-slip active deformation was determined as 9 km at Izmit basin and 3.8 km at Sapanca Lake basin. Further, the minimum principal stress axes (σ3) vary in the trending ranges of N11°-74° E, which are caused by the transtensional stresses associated with strikeslip faulting in the Izmit Basin by a different tectonic source than the Sapanca Lake Basin. Besides, the crust depth of main strand of NAFS-NB was determined up to 1112 m by magnetic method. The secondary faults were determined by both magnetic and resistivity methods up to a depth of 110 m. The depression area between Izmit bay and Sapanca Lake on the northern Anatolian fault is an integrated basin with two dextral strike-slip tectonic origins. Thus, the Izmit Basin, along with the main strike-slip faulting, has been developed in the asymmetric negative ower structure, where only the southern boundary has become a fault. The Sapanca Lake Basin is a lazy-Z-shaped pull-apart system formed by the E-W trending fault as a releasing bend. A simple shear deformation ellipsoid with a long axis of approximately 35 km on the Northern Branch of the North Anatolian Fault System is de ned for the Izmit-Sapanca integrated basin. Therefore, intra-basin deposits have different depths estimated from the gravity data in the Izmit-Sapanca integrated basin, and the maximum sediment thickness estimated is 2200 m in the middle of the Izmit Basin. Ogawa et al. 2001; Ogawa and Honkura 2004). Ateş et al. (2003) have identi ed the faults in the deep section of the crust along the NAFS-NB based on the high-speed zones and the regions where coincident with gravity and magnetic highs. Bohnhoff et al. (2016b), suggested that a coseismically introduced lateral and vertical slip de cit is systematically compensated postseismically in both the brittle and ductile portions of the crust in east Marmara region. This study explains the development of an integrated basin-like ISIB consisting of Izmit basin and Sapanca Lake basin with different basin morphology, located on a right-lateral strike-slip fault (NAFS). In this sense, the deformation geometry of the active structural elements, which are associated with lithofacies features, the sedimentary processes of the basin-lling formations, and which are different from each other in each basin, are formed from the surface to a certain depth of the upper crust. The tectonostratigraphic observations made on the surface were correlated with the geophysical data collected by the resistivity, magnetic, gravity, and joint inversion methods, identi ed the traces of active deformation in the upper depths of the ISIB. Thus, the characteristics and genesis of tectonic sources such as type, length, N-S range and width, creating the deformation zone in the continental crust were studied. The difference of this study from previous studies is that the geometry of the secondary active faults, which play an important role in the setting of the basins in the region, together with the NAFS-NB main fault, was determined by comparing with the geophysical data obtained from both the surface and the deep. Accordingly, the fault types were detailed in three dimensions and it was determined that IB and SB are integrated basins in two different geometries with different deformation areas, and NAFS-NB was the main tectonic source for these basins to take their present shape. 2 Study Area The study area covers the İzmit basin-Sapanca Lake integrated basin (ISIB) consisting of IB with 21 x 11 km 2 and SB with 15 x 6 km 2 (Fig. 1b). The geology of the southern uplift of the ISIB belongs to Armutlu-Ovacık Zone, whereas the geology of the northern uplift of the ISIB belongs to İstanbul-Zonguldak Zone (Yiğitbaş et al. 1999), (Figs. 1a, 2). Both of these uplifts consist of the pre-Plio-Quaternary period rocks and structures. The ISIB developed during the Plio-Quaternary period (
THE EAST ANATOLIAN FAULT SYSTEM; THOUGHTS ON ITS DEVELOPMENT
A fault zone consisting of left-lateral strike-slip faults extends between Karlıova and Hazar Lake, in Eastern Turkey. This major fracture zone must have been caused by the same compressional forces that formed the low-angle thrust faults belt in Southeastern Turkey. Between Hazar Lake and Genç the fault zone follows a primary zone of weakness. The segment of the fault zone between Karlıova and Bingöl was probably formed by subordinate fracturing of a tectonic plate. Bingöl-Genç segment takes place between these two main segments. Strike and slip characteristics of the fractures associated with 1971 earthquake agree with the view that the region is under north-south acting compressional forces.
Tectonophysics, 2000
The Tasova-Erbaa and Niksar basins are two adjacent pull-apart basins along the North Anatolian Fault Zone (NAFZ). Within the Tasova-Erbaa basin, sedimentary lithofacies of the Upper Pontus Formation (Plio-Pleistocene) are asymmetrically distributed, with laterally derived alluvial fans, coarse braid plain deposits, and axial braided stream deposits dominating the northern and western parts of the basin. The basin has gently dipping sediments locally affected by pervasive extensional (T) faulting. Isolated compressional structures are associated with master faults (deformation zone width ≤500 m). Pervasive extensional faults (T and R?) and late-stage PDZ-parallel compressional faults are also present. An additional set of extensional faults trends perpendicular to the PDZ, accommodating secondary pull-apart stretching within the basin. The distribution of sedimentary facies and structural styles is consistent with that predicted by models for pull-apart basins. The adjacent Niksar basin is an active pullapart basin, possibly as young as 0.5-1 Ma. Its modern drainage and sedimentary facies are symmetrically arranged. Adding the lengths of the Tasova-Erbaa and Niksar basin suggests~80 km total displacement along the North Anatolian fault, which is consistent with Seymen (ITU Ph.D. Thesis, 1975), Sengor [J. Geol. Soc. 136 (1979) 269-282] and Armijo et al. [ Tectonophysics 243 (1999) 135-154], who observed about 85±5 km total displacement along the North Anatolian fault. The change in course of the North Anatolian fault, marked by the formation of the Niksar-Ezinepazari segment, and this new geometry suggest that the Anatolian block is rotating anticlockwise by having two separate poles: one located near Damascus and the other occurring north of the Sinai peninsula. This change may also mark the transfer of the Anatolian triple junction from Erzincan to Karliova about 1 Ma ago. Furthermore, it appears that while the fault shortcuts the older basin, a new generation of pull-apart basins are formed due to changes of boundary conditions along the fault zone.
The Kinematics of the East Anatolian Fault Zone, Eastern Turkey and Seismotectonic Implications
International Journal of Engineering and Applied Sciences
One of most prominent and active faults in Eastern Turkey is the NE-SW oriented left-lateral strike-slip East Anatolian Fault Zone (EAFZ) with a length of approximately 500 km. In this study, we have examined the recent seismicity of EAFZ that was obtained from the records of 34 three-dimensional broad-band earthquake stations established around the fault zone within TURDEP project since 2006. Further the seismicity and fault mechanism solutions of EAFZ, Eastern Turkey have been examined. The new fault mechanism solutions in addition to previously published 220 earthquakes, with a magnitude of ML=2.0 or more were determined by a local moment tensor solution and P-wave first motion data. It was suggested that the recent tectonic deformation of EAFZ south of Türkoğlu was taken up by the left-lateral strike-slip active faults in between Amik and Adana Basins were young trans-tensional stress regime was also active.
Tectonic structures along the North Anatolian fault zone, northeast of Refahiye (Erzincan)
Tectonophysics, 1975
A 22 km long segment of the still active North Anatolian fault zone has been studied. The main fault can be observed clearly in the field and on aerial photographs, and it trends 105' in the mapped area. Antithetic en-echelon faults are less common, synthetic en-echelon faults are more abundant. There are some examples of en-echelon folds, related to wrenching, in the Pliocene sediments. Some fractures are oriented nearly parallel with, and some others perpendicular to the axes of the folds. The observed structures appear to be similar to those observed in clay-model experiments, suggesting that the North Anatolian fault zone has been formed by a force couple, oriented nearly E-W. Geologic evidence is found indicating that the fault movement begun before Pliocene time. Further investigations are necessary to estimate the amount of displacement and the age of the fault. Magnesite occurrences in the area, which are genetically related to the wrenching and the presence of fold structures, which might be sites for oil traps, are indications of the economic importance of the North Anatolian fault zone.