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In this study, marine Pleistocene mollusc faunas from deposits along the southern shores of the Izmit Bay area (Marmara Sea, Turkey) are reviewed. Ten samples from five localities spanning middle and late Pleistocene intervals are assessed and compared to four samples of a Holocene age. For the Pleistocene fauna, a total of 59 mollusc species (33 bivalve and 26 gastropod species) are recorded, some of which are reported for the first time for this region. The middle Pleistocene fauna bears large resemblance to the late Pleistocene faunas, even though marine conditions were lacking during sea-level drops in the Marmara Sea Basin in intervening times. The middle Pleistocene mollusc fauna is dominated by species that typify the so-called Uzunlarian faunas while the late Pleistocene mollusc fauna is indistinguishable from Karangatian faunas of the Black Sea Basin. Several common species (including Bittium reticulatum , Rissoa spp. and Lucinella divaricata ) show that the both Uzunlarian and Karangatian assemblages of Yalova fauna mainly represent seagrass palaeoenvironments. Palaeosalinities estimates for the Yalova area are uppermost mesohaline to polyhaline, typically around or above 20 psu, which is almost similar to the optimum salinity estimates for the middle Pleistocene Uzunlarian. However, it is slightly lower then the Upper Pleistocene Karangatian, representing the location of the Yalova area in an embayment with freshwater input at that time. The Yalova sections are located in the southern flank of the North Anatolian fault system responsible for a strong local uplift of the study area. The sections contain evidence for three marine high stands, separated by terrestrial intervals. When regional uplift rates (approximately 0.2 mm/y) and oceanic sea-levels are considered it is likely that the three highstand intervals correspond to relative sea level high stands of MIS7, MIS5e and possibly MIS5d but further study is required to confirm such a suggestion. [ABSTRACT FROM AUTHOR]

We invert the present day states of stresses for five apparent earthquake clusters in the Northern branch of the North Anatolian Fault in the Sea of Marmara. As the center of the Sea of Marmara is prone to a devastating earthquake within a seismic gap between these selected clusters, sensitive analyses of the understanding of the stress and strain characteristics of the region are all-important. We use high quality P and S phases, and P-wave first motion polarities from 398 earthquakes with ML ≥ 1.5 using at least 10 P-wave first motion polarities (FMPs), and a maximum of 1 inconsistent station, obtained from a total of 105 seismic stations, including 5 continuous OBSs. We report here on large numbers of simultaneously determined individual fault plane solutions (FPSs), and orientations of principal stress axes, which previously have not been determined with any confidence from the basins of the Sea of Marmara and prominent fault branches. We find NE–SW trending transtensional stress structures, predominantly in the earthquake clusters of the Eastern Tekirdağ Basin, Eastern Çınarcık Basin, Yalova and Gemlik areas. We infer that a dextral strike-slip deformation exist in the Eastern Ganos Offshore cluster. Furthermore, we analyze FPSs of four ML ≥ 4.0 earthquakes, occurred in seismically quiet regions after 1999 Izmit earthquake. Stress tensor solutions from a cluster of small events that we have obtained, correlate with FPSs of these moderate size events as a demonstration of the effectiveness of the small earthquakes in the derivation of states of local stresses. Consequently, our analyses of seismicity and large numbers of FPSs using the densest seismic network of Turkey contribute to better understanding of the present states of the stresses and seismotectonics of the Sea of Marmara. [ABSTRACT FROM AUTHOR]

Abstract: In closed marine basins and large lakes, gravity re-depositional processes often result in specific turbidites with two abruptly separated layers: a coarse graded lower term and an upper homogenous fine-grained term. An additional mixed term generally occurs in between, indicating to and from particle displacements. The later ones are related to oscillating bottom currents responsible for a high increase of the fine fraction segregation, within the reworked wasted mass. The whole sedimentary event is the association “homogenite+turbidite” (HmTu), which specific a settling condition area here characterized through Anisotropy of Magnetic Susceptibility (AMS). Homogenites's magnetic foliation appears anomalously high with respect to their expected state of compaction, and strikingly higher than hemipelagites's values. We applied this approach to Late Pleistocene/Holocene sediments from the Sea of Marmara and from the Gulf of Corinth. Grain-size and other magnetic parameters related to mineralogy are added to better assess the granular array influence on AMS. As HmTu is considered as often related to earthquake-triggering and tsunami/seiche effects, AMS appears as a useful tool for subaqueous paleoseismic investigations. First, it may evidence the signature of paleo-earthquakes; second, it permits to decipher hemipelagic intervals which are inferred to represent the time elapsed between two successive reworking events. [Copyright &y& Elsevier]