Evidence for widespread creep on the flanks of the Sea of Marmara transform basin from marine geophysical data

"Wave" fields have long been recognized in marine sediments on the flanks of basins and oceans in both tectonically active and inactive environments. The origin of "waves" (hereafter called undulations) is controversial; competing models ascribe them to depositional processes, gravity-driven downslope creep or collapse, and/or tectonic shortening. Here we analyze pervasive undulation fields identified in swath bathymetry and new high-resolution multichannel seismic (MCS) reflection data from the Sea of Marmara, Turkey. Although they exhibit some of the classical features of sediment waves, the following distinctive characteristics exclude a purely depositional origin: (1) parallelism between the crests of the undulations and bathymetric contours over a wide range of orientations, (2) steep flanks of the undulations (up to ∼40°), and (3) increases in undulations amplitude with depth. We argue that the undulations are folds formed by gravity-driven downslope creep that have been augmented by depositional processes. These creep folds develop over long time periods (≥0.5 m.y.) and stand in contrast to geologically instantaneous collapse. Stratigraphic growth on the upslope limbs indicates that deposition contributes to the formation and upslope migration of the folds. The temporal and spatial evolution of the creep folds is clearly related to rapid tilting in this tectonically active transform basin

Investigation of Çınarcık Basin and the contunation of North Anatolian Fault in Marmara Sea with multi channel seismic data

Marmara Denizi, aktif tektonik yapısı ve Kuzey Anadolu Fay Zonu'nun (KAFZ) yaratmış olduğu aktif depremsellik nedeniyle birçok araştırmacı tarafından odak konusu haline gelmiştir. KAFZ Marmara Denizi içerisinde 3 kola ayrılıp devam etmesi nedeni ile tartışma konularına açık hale gelen karmaşık bir tektonik yapıya sahip olmuştur. Tez kapsamında İstanbul'a yakınlığı ile de bilinen aktif bakımdan oldukça önemli olan Çınarcık Havzası incelenmiştir. Havza için yapılan bu çalışmada 2008 yılında gerçekleştirilen TAMAM (Turkish American Multichannel Project) ve 2010 yılında gerçekleştirilen TAMAM-2 (PirMarmara) seferlerinde R/V K. Piri Reis gemisi tarafından toplanan çok kanallı sismik yansıma verileri ve Fransız deniz araştırma enstitüsü olan Ifremer kurumunun hazırladığı yüksek ayrımlı batimetri haritası kullanılmıştır. TAMAM projesi ile birlikte yaklaşık 3000 km yüksek çözünürlüklü çok kanallı sismik yansıma verisi toplanmıştır. Çalışma kapsamında havzanın fay haritası ayrıntılı bir şekilde ortaya konmuştur ve birçok çalışmada bahsedilen havzanın güney yamacında konumlanan büyük ölçekli bir fayın varlığı araştırılmış, böyle bir fayın varlığına rastlanmamıştır. Çok kanallı sismik yansıma verileri sayesinde havza çökellerinin sismik stratigrafik yorumlamaları yapılmıştır. Havza içerisinde oluşan faylanmanın en aktif olduğu yerde yapılan hesaplama işlemi ile havzanın kuzey-güney yönlü yıllık kümülatif açılması hesaplanmıştır. Ayrıca havza içerisinde paralel şekilde çökelen tabakaların eğimlerinden yararlanılarak ve bu hesaplanan eğimlerin küresel deniz seviyesi değişimleri ile eşleştirilmesinden tabaka yaşları hesaplanmaya çalışılmıştır. Marmara Sea is an important area for investigations due to its tectonic structure and remarkable seismic activity of North Anatolian Fault Zone (NAFZ). As NAFZ separates into 3 branches in the Marmara Sea, it has a complicated tectonic structure which gives rise to debates among researchers. Çınarcık Basin, which is close to İstanbul and very important for its tectonic activity, is studied in this thesis. Two different multichannel seismic reflection data were used in this thesis. First data were acquired in 2008 in the frame of TAMAM (Turkish American Multichannel Project) and second data were in 2010 in the frame of TAMAM-2 (PirMarmara) onboard R/V K.Piri Reis. Also high resolution multibeam data were used which is provided by French Marine Institute IFREMER. In the scope of TAMAM project total 3000 km high resolution multi channel data were collected. In this study, a detailed fault map of the basin is created and the fault on the southern slope of the basin which is interpreted by many researchers in many publications was investigated. Tnd there is no evidence that such a fault exists on the southern part of the basin. With the multichannel seismic reflection data seismic stratigrafic interpretations of the basin deposits were done. The yearly cumulative north-south extension of the basin was calculated by making some calculations on the most active part of the faulting in the basin. In addition, the tilt angles of parallel tilted sediments were calculated and correlated with global sea level changes to calculate ages of the deposits in the basi

Marmara Adası Güneyi ve Erdek Körfezi'nin Çok Kanallı Sismik Yansıma Yöntemi ile Tektonik Yapısının İncelenmesi

The Sea of Marmara is one of the most important active tectonic areasunder the influence of many faults belonging to the North AnatolianFault Zone (NAF), one of the most active tectonic structures of Turkey.It is known that the NAF is divided into three branches named asNorth, Middle and Southern branches within the Sea of Marmara.Among these branches, the middle branch fault system extends alongthe southern shelf of the Sea of Marmara and is distributed over theentire shelf from the west to the east. Therefore, the south of theMarmara Sea is at least as important as the northern part and has thepotential to produce earthquakes. The study area covers the Erdek Bay,located in the west of the Kapıdağ Peninsula in the southwest of theMarmara Sea, and the region between the Marmara Island and KapıdağPeninsula. Therefore, the study area is under the influence of the NorthAnatolian Fault. Today, the models of the Marmara Sea are still thesubject of the discussions by many researchers. Especially, the ideathat the main fault passes from the north has been revealed by manyresearchers and the majority of the attention has been drawn on thismain branch. However, this fault system, which has a very complexstructure in the Marmara Sea, has many effects in the southern partalso. Although there are a lot of researchs about the tectonics of theNorthern branch and the general Marmara Sea, studies for the southernregion are very limited.In this study, in order to reveal the tectonic structure of the south of theMarmara Sea in 2013 and 2014, multichannel seismic and sparkerseismic reflection datasets collected within the scope of the TUBİTAK112Y026 (NSF-TÜBİTAK) project named as SoMAR, jointlyconducted by the Institute of Marine Sciences and Technology ofDokuz Eylül University and the Institute of Lamont-Doherty EarthObservatory of Columbia University.In the northern part of the study area, there is a fault system called theKapıdağ Fault and has strike-slip characteristics. Within the scope ofthe study, it is aimed to reveal the direction of this fault system in theregion in detail. One of the aims of the study is to create a fault map ofthe Erdek Bay of the Sea of Marmara and to reveal the activity of thesefaults since late Quaternary time. The acoustic basement is observedin almost all of the study area. The acoustic basement observed atshallower depths in the south is cut by many faults.The tectonics ofthis region are also studied in detail, including shallow faults anddeeper faults that can be traced to the basement. These faults aremapped among themselves as active and inactive faults. In addition, tothe extent that it can be observed, the horizons on the acousticbasement are also interpreted stratigraphically.</p

Güneydoğu Marmara Şelfinin Sismo-akustik Yapısı

Since Turkey is located in one of the most active earthquake zones inthe world, there is an earthquake risk in almost the whole country.Considering the studies carried out by many researchers, the historicalearthquakes in the region and especially the 17 August 1999earthquake that caused great destruction, it is understood that theearthquake potential of the Marmara Region is quite high. It is knownthat the North Anatolian Fault (NAF), which continues along thenorthern line of Anatolia, is one of the most seismically active faultsin the world, and this fault is divided into many small fault brancheswith three main branches in the Sea of Marmara. These main branchesare named as the Northern Branch, the Central Branch and theSouthern Branch. Therefore, in the Sea of Marmara, many differentfault types are seen together with the effect of different branches aswell as lateral faults. Previous studies have revealed that manyearthquakes have occurred in the Sea of Marmara are concentrated onthe northern branch of the NAF, and also showed that the earthquakesoccurring on this branch are more than the other branches. However,as the studies on the central branch on the Southern Marmara shelf arelimited, there is no detailed information in the literature about theregion. Since this fault system, which has a very complex structure inthe Marmara Sea, has many effects in the south, it is necessary toevaluate possible large-scale earthquakes that could be caused bymany faults belonging to the NAF.Within the scope of the study, the region between the KapıdağPeninsula and the İmralı Island located on the southern shelf of theMarmara Sea, is being studied tectonically. Throughout the study,multi-channel seismic reflection and sparker seismic reflectiondatasets collected within the scope of the TUBİTAK 112Y026 projectnamed as SOMAR, carried out in 2013 and 2014 to examine thesouthern shelf of the Marmara Sea. In total, approximately 750 km ofmulti-channel seismic reflection, 420 km of sparker seismic reflectionand 450 km of engineering seismic (chirp) datasets were processed andtheir initial interpretations were done.Acoustic data collected within the scope of the study has a penetrationthat we call the middle range, so the faults seen up to this depth aremapped as active and inactive faults. In addition, since the acousticbasement is at a depth that the data can penetrate in the southern partof the study area, the basement in this region has been interpreted indetail and the faults traced to the basement have been revealed. Thelevels above the acoustic basement will be interpreted stratigraphicallyduring the study and horizon maps will be created.</p