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Figure 1. The Istanbul-Uskudar isthmus

separates the Sea of Marmara from theBlack Sea. Exploration was carried out inareas designated A, B and C south of theisthmus and area D located north of it.Area Ais located at the ekmecesubmarine canyon, area B south ofPrince Island, and area C is located southof the southern edge of the BosporusStraits, all in the Sea of Marmara. Area Dis located in the Black Sea, at the shelfedge north of the Straits. Note theorientational similarity between theBosporus and other valleys in theisthmus.

Figure 2-a. Area 1_2 in the Black Sea is aprime example of the researchmethodology of dense lattice of seismicprofiles. On board interpretation of thechirp survey led to sophisticated mappingof the seafloor and subsurfaceunconformities. The isopach map isbetween unconformity 1 and theseafloor.

Figure 2-b. Track chart and bathymetry ofthe eastern flank of ekmece Canyon.Contours in seconds of reflection time(TWT). The depth of the Straits of theDardanelles, 86 m, is equivalent to the0.114 sec TWT, but the transition from thegently dipping continental shelf to thesteeply dipping continental slope occursat reflection time ca 0.13 (change fromyellow to red), that equals to 97.5 m.

Figure 3-a. Sevaral coastal terraces alongthe ekmece shelf, NE Sea of Marmarawere discerned at 98, 93 and 86 m waterdepths. The Dreissena shells indicatefresh-water depositional facies. Coresobtained at MeDex05 cruise are markedby green circles. See Table I for additionaldata regarding the cores.

Cruise reportofR/V Mediterranean Explorer Black Sea Expedition21st July 3rd August 2005

William B.F. Ryan1, Yossi Mart2 and M. Namik agatay3

Co-Chief Scientists

Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, 10964, USA.1Recanati Institute for Marine Studies, University of Haifa, Haifa 31905, Israel .2Division of Geology, Faculty of Mineral Resources, Istanbul Technical University, Istanbul, .3Turkey

October 2005

Variable sealevels and flooding phenomena in the Sea of Marmara andthe Black Sea during the latest Pleistocene and the early Holocene

IntroductionAgeological and geophysical marine survey was carried out along both sides of the Bosporus(Istanbul) Straits, both in the Sea of Marmara and the Black Sea, from 21st July to 3rd August,2005 on board R/V Mediterranean Explorer. The survey was a joint project of earth scientistsfrom Turkey, the U.S.A, and Israel, and its purpose was to elucidate the details of the transitionof these two aquatic bodies from lakes to seas in the late Pleistocene and the early Holocene.The survey encompassed ca. 1000 km of high-resolution seismic profiles and obtained 14gravity cores. Our analysis of these data suggests that both seas were fresh to brackishwaterlakes at the late Pleistocene, and that the marine flooding of both seas was abrupt. Specificevidence for extensive subaerial erosion on the present continental shelf was encountered in.the Black Sea which preceded the subsequent intensive marine flooding

RationalConflicting geological and geophysical articles regarding the water composition of the Sea ofMarmara and the Black Sea and their changing levels and variable composition during thelatest Pleistocene and the earliest Holocene were presented during the last 12 years in thescientific literature. While it is generally agreed that fresh water lakes occurred in those basinsafter the Last Glacial maximum (LGM), when global sealevel was 125 m lower than thepresent level, there is disagreement on the mode in which the Sea of Marmara and the Black

Sea changed into their present marine environment as global sealevel was rising in the latestPleistocene and the early Holocene. While some persistently argue that a steady aquaticconnection existed between the Black Sea and the Sea of Marmara after the LGM (e.g. Aksu etal., 2002), accumulating evidence suggests that abrupt marine flooding took place first inMarmara Lake and then in the Euxenic Lake, the fresh water predecessor of the Black Sea, inthe latest Pleistocene and the early Holocene, respectively (e.g. Cagatay et al., 2000; Grr etal., 2001; Major et al., 2002). In an effort to explore this dispute further, an international marinegeological exploration was carried out in the Sea of Marmara and the southern Black Seaduring July 21 August 3, 2005 aboard the R/V Mediterranean Explorer, to advance theinvestigation of the sub-recent to recent geological history of the Black Sea and the Sea ofMarmara, and their interconnection with the Mediterranean Sea after the Last Glacial.Maximum

Participants:Co-Chief scientistsProf. M. Namik agatay, ITU-EMCOL, Maden Fakultesi, Istanbul Technical University, Istanbul,TurkeyProf. Yossi Mart, Recanati Institute for Marine Studies, University of Haifa, Haifa, Israel

Prof. William B.F. Ryan, Lamont-Doherty Earth Observatory, Columbia University, Palisades,NY, USA

ScientistsMr. Kedir Eris, ITU-EMCOL, Maden Fakultesi, Istanbul Technical University, TurkeyDr. Liviu Giosan, Woods Hole Oceanographic Institution, Woods Hole, MA, USADr. Cecilia McHugh, Queens College, City University of New York, Flushing, NY 11367, andLamont-Doherty Earth Observatory, Columbia University of New York, Palisades, NY, USADina Vachtman, Department of Geography and Environmental Studies, Ben Gurion University,Beer Sheva, Israel

SupervisorsDr. Kerim Sarikavak, MTA, Ankara, TurkeyProf. Atilla Ulug, Dokuz Eylul University, Izmir, Turkey

EquipmentThe expedition was conducted from R/V Mediterranean Explorer, which was equipped withchirp sub-bottom imaging system that was linked to the GPS navigation system. The chirpdata were analyzed on board using the Kingdom Suite interpretation package, which hadbeen donated both to the University of Haifa and to Columbia University by SeismicMicrotechnologies Inc. of Houston, TX. The expedition also deployed a 3 m long, 10 cmdiameter gravity corer. With this equipment the expedition obtained nearly 1000 km of chirpprofiles and 14 cores. The seismic profiles were interpreted on board, and the cores weresplit open, described and sampled right after their acquisition. The seismic data were

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Figure 3-b. Schematic interpretation of theChirp profile (a) shows foredeltadepositional patterns along the shelf-slope transition zone of the northeasternSea of Marmara off the ekmece Canyon.The gradient of the present seafloorincreases seawards of the shelf edge,and similar features can be discerned inthe older strata. The unconformity at thebase of the Holocene sediments (heavydashed line) truncated the upper portionof the prograding sedimentarysequences. The level of the unconformityis deeper than 86 m (0.1147 sec reflection

time), is deeper than the paleo-sill depthof the Dardanelles Straits, suggestingsubaerial exposure of the Marmara shelfwhen global sealevel was lower than 86m, before the Younger Dryas Period.Location of core #3 is shown on the chirpprofile. Core #5 is projected from theKurbagali delta.

Figure 5. The three areas surveyed in the

Black Sea are shown in frames blocks.The eastern block is a multibeam map ofthe inflow canyon along proximalcontinental slope. Li