9Holocene earthquake history of the Central High Segment of the North Anatolian Fault is 10 examined here for the first time based on analysis of seismoturbidites within a 21-m-long piston 11 core recovered from the Kumburgaz Basin in the Sea of Marmara. The visual lithological 12 description combined with detailed grainsize analyses indicate that the deep basin hemipelagic 13 sediments are interrupted by 28 turbidite units during the last 6.1 cal kyrs BP. The turbidites 14 show strong segregation and a sharp boundary between a coarse basal part and overlying 15 homogenite as inferred from detailed sedimentological and geochemical data. Several 16 amalgamated turbidites are recognized by repeated fining upward sequences with no 17 intervening homogenite indicating multiple episodes of traction and deposition as a result of 18 various slope failures and turbidity currents. Each unit was possibly triggered by the same 19 earthquake event rupturing in the Sea of Marmara. The most common sedimentary feature is 20 the continuous parallel lamination that was presumably introduced by long lasting water 21 oscillations on suspended sediments due to the seiche effect. The establishment of geochemical 22 criteria and exclusive sedimentary processes distinguish earthquake triggered turbidites 23 (seismoturbidites) from other trigger factors. Moreover, such distinction allows us to evaluate 24 2 hydrodynamic sedimentary conditions and processes in the Kumburgaz Basin. The base of most 25 seismoturbidites are associated with a sharp increase in Mn concentration that can be explained 26 by a diagenetic enrichment of Mn at the oxic/anoxic interface of the sediments near the seafloor 27 prior to the deposition of the turbidite. An age-depth model of the studied core based on seven 28 AMS 14 C ages allows precise correlation between historical earthquakes and seismoturbidites 29 in the Kumburgaz Basin. At least the latest nine of them fit well with the previously recorded 30 major earthquake events between ca. ~500 cal yrs BP and 2.5 cal kyrs BP.31

IntroductionPaleoseismology is a powerful technique to study the earthquake history and potential of active faults. Previous paleoseismology studies along normal fault systems have provided important information regarding the seismotectonic behaviour, timing, slip rates, size, and intervals of past earthquakes (

Multi-proxy analyses and lithology of two cores, MRS-CS18 and MRS-CS27, from the İmralı Basin of the Sea of Marmara (SoM) provide important new information on environmental conditions, relative sea level, and sill depths of the straits of Bosporus and Dardanelles during the marine isotope stages (MIS) 5 and 6. The fossil and multi-proxy geochemical records show that lacustrine conditions prevailed in the SoM during most of MIS-6, from 173 to 134 ka BP, and that the transition to marine conditions during Termination II took place at~134.06±1.10 ka BP. MIS5 interstadials a, c, and e witnessed the formation of three sapropels (MSAP-4, MSAP-3 and MSAP-2) under suboxic to anoxic marine conditions, whereas during stadials MIS5b (~94-86) and MIS5d (~112-105 ka BP), lacustrine and marine conditions with deposition of sediments having relatively low TOC contents (<2 %) prevailed, respectively. Consideration of the global sea level, together with the timing of the marine reconnection of the SoM during Termination II and persistence of the marine conditions during MIS5, except for the MIS5b, suggests that the Dardanelles sill depth was at~-75±5 m during the reconnection at Termination II and at-55±5 m during most of MIS5. On similar considerations of the Black Sea marine reconnections and disruptions during the MIS5, a sill depth of-35 to-40 m (similar to the present day depth) is indicated for the Bosporus Strait. The SoM geochemical proxy records correlate well with the regional terrestrial and marine records and the NGRIP oxygen isotope record with its glacial and interglacial (GI) phases, showing the common effect of the North Atlantic climatic events triggered by the perturbations in the Atlantic Meridional Overturning Circulation (AMOC). However, the amplitude of the oscillations recorded in the SoM during MIS6 (Penultimate Glacial Period) is relatively smaller compared to the MIS4 to MIS2 (Last Glacial Period).

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