SeismicstratigraphyofLateQuaternarydepositsfromthe ... · around the greater Istanbul area, the...

Seismic stratigraphy of Late Quaternary deposits from thesouthwestern Black Sea shelf : evidence for non-catastrophic

variations in sea-level during the last V10 000 yr

A.E. Aksu a;�, R.N. Hiscott a, D. Yas'ar b, F.I. Is'ler a, S. Marsh a

a Department of Earth Sciences, Centre for Earth Resources Research, Memorial University of Newfoundland,St. John’s, NF, Canada A1B 3X5

b Institute of Marine Sciences and Technology, Dokuz Eylu«l University, Haydar Aliyev Caddesi No: 10, Inciralt|, 35340 Izmir, Turkey

Received 7 May 2001; accepted 19 February 2002

Abstract

Detailed interpretation of single channel seismic reflection and Huntec deep-tow boomer and sparker profilesdemonstrates that the southwestern Black Sea shelf formed by a protracted shelf-edge progradation since theMiocene^Pliocene. Five seismic^stratigraphic units are recognized. Unit 1 represents the last phase of theprogradational history, and was deposited during the last glacial lowstand and Holocene. It is divided into foursubunits: Subunit 1A is interpreted as a lowstand systems tract, 1B and 1C are interpreted as a transgressive systemstract, and Subunit 1D is interpreted as a highstand systems tract. The lowstand systems tract deposits consist ofoverlapping and seaward-prograding shelf-edge wedges deposited during the lowstand and the subsequent initial riseof sea level. These shelf-edge wedges are best developed along the westernmost and easternmost segments of the studyarea, off the mouths of rivers. The transgressive systems tract deposits consist of a set of shingled, shore-parallel,back-stepping parasequences, deposited during a phase of relatively rapid sea-level rise, and include a number ofprograded sediment bodies (including barrier islands, beach deposits) and thin veneers of seismically transparent mudsshowing onlap onto the flanks of older sedimentary features. A number of radiocarbon dates from gravity cores showthat the sedimentary architecture of Unit 1 contain a detailed sedimentary record for the post-glacial sea-level risealong the southwestern Black Sea shelf. These data do not support the catastrophic refilling of the Black Sea bywaters from the Mediterranean Sea at 7.1 ka postulated by [Ryan, Pitman, Major, Shimkus, Maskalenko, Jones,Dimitrov, Go«ru«r, Sak|nc', Yu«ce, Mar. Geol. 138 (1997) 119^126], [Ryan, Pitman, Touchstone Book (1999) 319 pp.],and [Ballard, Coleman, Rosenberg, Mar. Geol. 170 (2000) 253^261].Crown Copyright D 2002 Elsevier Science B.V. All rights reserved.

Keywords: Black Sea; sea level; sequence stratigraphy; transgressive systems tracts

1. Introduction

The Black Sea is an east^west trending ellipticalland-locked basin, situated between the NorthAnatolian (Pontides) Mountains of northern Tur-

0025-3227 / 02 / $ ^ see front matter Crown Copyright D 2002 Elsevier Science B.V. All rights reserved.PII: S 0 0 2 5 - 3 2 2 7 ( 0 2 ) 0 0 3 4 3 - 2

* Corresponding author. Tel. : +1 709-737-8385;Fax: +1 709-737-2589.

E-mail address: [email protected] (A.E. Aksu).

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Marine Geology 190 (2002) 61^94

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key in the south and the Caucasus and CrimeaMountains of southern Russia and Ukraine inthe north and northwest (Fig. 1). It is connectedto the eastern Mediterranean via the Strait ofBosphorus ( = Strait of Istanbul; sill depth of340 m), the marginal Marmara Sea, the Straitof Dardanelles ( = Strait of C'anakkale; sill depthof 370 m) and the Aegean Sea.The southwestern Black Sea shelf is a generally

£at, gently north-dipping platform dissected by aprominent channel (Bosphorus Channel) whichconnects the Strait of Bosphorus to the Bospho-rus Canyon (Fig. 2). The channel is 200^500 mwide and 10^25 m deep and separates the shelfregion into a 10^17-km-wide eastern shelf and a25^35-km-wide western segment. The shelf^slopebreak in both areas occurs at V115^120 m waterdepth, with 5^9‡ slopes leading to the £oor of theBlack Sea basin at V2200 m, also known as theEuxine Abyssal Plain (Figs. 1 and 2). The slope isdissected by numerous submarine canyons andgullies.In recent years, there has been a renewed inter-

est in the Black Sea region, associated with astudy of the northern Black Sea shelf by Ryanet al. (1997) who suggested that the Black Seabecame a giant freshwater lake during the last

glacial maximum, with the water level standingat 3150 m, and that during the post-glacial sea-level rise at V7.15 ka the Mediterranean Seabreached the Strait of Bosphorus, catastrophicallyre-¢lling the Black Sea basin and contributing tothe Noah’s Flood myth (Mestel, 1997). A numberof related papers and popular-press articles havebeen published since (e.g. Ryan and Pitman,1999; McInnis, 1998; Brown, 1999; Ballard etal., 2000; Uchupi and Ross, 2000) discussing thee¡ects and implications of this perceived cata-strophic oceanographic event. This hypothesis iscontradicted by Aksu et al. (1999), who suggestedthat it was instead the Black Sea that ¢rstbreached the Bosphorus and over£owed into theMarmara Sea during the early Holocene. Theyshowed that, in the western Marmara Sea, sandwaves and current-generated marine bars indicateunidirectional southerly to westerly £ow prior tothe deposition of a veneer of Holocene surfacemuds. Hiscott and Aksu (2002) infer, based onradiocarbon dates from cores, that the sur¢cialmud drape started to accumulate at or beforeV9 ka. The Ryan et al. (1997) hypothesis isalso contradicted by multi-proxy climatic andoceanographic data from Aegean Sea cores whichshow that the Holocene in the Aegean Sea began

Fig. 1. Location map of the Black Sea, showing the surface water circulation (from Ogfluz et al., 1993). Inset is the study areaillustrated in Fig. 2.

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A.E. Aksu et al. /Marine Geology 190 (2002) 61^9462

with a V10‡C increase in sea-surface temperatureand 1.0^1.5x decrease in sea-surface salinity(Aksu et al., 1995a,b). Aksu et al. (2002) arguethat the excess freshwater originated from in-creased river discharge into the Black Sea follow-ing a dry period at the glacial maximum. Net out-£ow of fresh water into the Aegean Sea provideda low-salinity surface lid, which prevented verticalmixing and ventilation, thus allowing the deposi-tion of the most recent sapropel S1 in the AegeanSea between 9.6 and 6.4 ka (Aksu et al., 1995a,b).The chronology of the paleoclimatic and pale-

oceanographic events associated with the last gla-cial^interglacial transition in the Black Sea andMarmara Sea, and the precise chronology ofsea-level variations vis-a'-vis the Bosphorus andDardanelles sills, are crucial for better under-standing of the communication between the BlackSea and eastern Mediterranean. This communica-tion likely controlled sapropel deposition in theAegean Sea, possibly the eastern MediterraneanSea, as well as the Black Sea. To delineate therole of this important gateway as a link betweenhigh-latitude Eurasia and low-latitude easternMediterranean Sea, the southwestern continentalshelf of the Black Sea was surveyed in 1998 and2000. In this paper, high-resolution seismic pro-¢les and short gravity cores are used to provide a

record of changing water levels and currents fromthe lowstand of the last glacial maximum to thepresent.

2. Physical oceanography and rivers

2.1. Physical oceanography

The water exchange between the Black Sea andthe eastern Mediterranean Sea occurs through theStraits of Bosphorus and Dardanelles as a two-layer £ow (Latif et al., 1992). The cooler (5^15‡C)and lower-salinity (17^20x) surface layer origi-nates from the Black Sea, and £ows south/south-west across the Straits of Bosphorus and Darda-nelles with velocities of 10^30 cm s31. This watermass forms a 25^100-m-thick surface veneer inthe Black Sea, the Marmara Sea, in the northeastAegean Sea. Warmer (15^20‡C) and high-salinity(38^39x) Mediterranean water £ows northalong the eastern Aegean Sea. The Mediterraneanmass plunges beneath the low-salinity surfacelayer in the northeastern Aegean Sea and pene-trates the Strait of Dardanelles £owing northeastwith velocities of 5^25 cm s31 (Oº zsoy et al., 1995;Polat and Tugflrul, 1996). The Mediterraneanwater mass occupies the entire Marmara basin

Fig. 2. Detailed bathymetry of southwestern Black Sea compiled using 12-kHz data collected during the R/V Koca Piri Reiscruises MAR98 and MAR00, supplemented by data from the International Bathymetric Charts of the Mediterranean, IBCM.Isobaths are in meters.

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A.E. Aksu et al. /Marine Geology 190 (2002) 61^94 63

below the 20^30-m-thick low-salinity surface ve-neer. It extends farther northeast across the Straitof Bosphorus with velocities of 5^15 cm s31, andpenetrates the Black Sea where it constitutes thebottom water mass below the 100^200-m-thicksurface layer (Oº zsoy et al., 1995; Polat and Tu-gflrul, 1996).Today there is a net export of V300 km3 yr31

of water from the Black Sea into the Aegean Seaacross the Straits of Bosphorus and Dardanelles(Oº zsoy et al., 1995). This out£ow results fromexcess precipitation over the Black Sea (V300km3 yr31) and freshwater input by large rivers(V350 km3 yr31), which together exceed evapo-ration (V350 km3 yr31) in the region. The Dan-ube, Dniester, Dnieper, Southern Bug and Donrivers drain V20% of central and eastern Europe(V2 million km2), and are the major sources offresh water entering the Black Sea (UNESCO,1969, 1993). The freshwater in£ow into the BlackSea shows large seasonal variations, with peakriver discharges occurring during April andMay. The narrow constriction at the Strait ofBosphorus forces the level of the Black Sea to£uctuate in perfect synchroneity with the interan-nual and seasonal variations of fresh water dis-charge into the basin, with a range of V50 cmmeasured at various monitoring stations over thelast century (Oº zsoy et al., 1995, 1996). Smaller-scale oscillations in the water level also occur inresponse to variations in barometric pressure(Oº zsoy et al., 1996). Satellite altimetry showsthat the surface of the Black Sea is, on average,30 cm (X 10 cm) above the level of the MarmaraSea (Bes'iktepe et al., 1994). The Marmara Sea,in turn, is approximately 5^27 cm above the

level of the northern Aegean Sea (Bogdanova,1969).The surface-water circulation in the Black Sea

is dominated by two large central cyclonic gyres(eastern and western gyres) and several smaller,anticyclonic coastal eddies (Fig. 1; Ogfluz et al.,1993). The narrow (6 75 km wide) counterclock-wise-rotating peripheral ‘Rim Current’ separatesthe cyclonic basinal gyres from the anticycloniccoastal eddies. This current £ows eastward alongthe Anatolian coast with velocities of V20 cm s31

and dominates the surface circulation across thenarrow continental shelves (Ogfluz et al., 1993).The weaker Bosphorus and Sakarya anticycloniceddies are situated west and east of the StraitBosphorus, respectively, and are con¢ned to thecoastal regions. Semidiurnal tides with a springtidal range of less than 8 cm do little to in£uencethe hydrodynamic regime in the Black Sea.In the southwestern Black Sea, the annual aver-

age signi¢cant wave height of 3.3^4.2 m corre-sponds to signi¢cant wave lengths of 77^100 mand periods of 7^8 s, respectively (database ofthe IMST). Longer-term observations show that100-yr storms generate wave heights of 6.0^7.2 m,with corresponding wave lengths of 157^190 mand periods of 10^11 s. These data indicate thatwave base for the 100-yr storm along the south-western Black Sea ranges between 80 and 95 m(i.e. half the signi¢cant wave length), suggestingthat, except near the mouths of rivers, the entireregion above the 95 m isobath is wave-dominated.

2.2. Rivers

Several small rivers drain into the southwestern

Table 1Hydrological data for small rivers discharging into the western Black Sea for the period between 60 and 1990 (from EIE, 1991)

River Drainage area Average discharge Annual discharge Sediment yield(km2) (m3 s31) (106 m3 yr31) (t yr31)

Bulan|k 155 1.597 59.5 9 987Pabuc' 95 0.907 27.5 5 395Kazan 125 1.262 45.2 7 619C'ilingos 91 0.887 39.9 5 111Kuzulu 40 0.368 12.3 1 817Riva 635 7.129 224.8 58 837Go«ksu 39 0.402 15.7 1 760

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Black Sea: Bulan|k, Pabuc', Kazan, C'ilingos andKuzulu rivers discharge west of the Bosphorus;whereas Riva, Go«ksu and Sakarya rivers dis-charge east of the Bosphorus (Fig. 2; Table 1).Bulan|k, Pabuc', Kazan, C'ilingos and Kuzuluhave a combined drainage area of 506 km2, aver-age combined annual discharge of 5.1 m3 s31,suspended sediment discharge of 0.95 kg s31,and corresponding combined annual sedimentyield of V29 930 t (Table 1). Riva and Go«ksurivers have a combined drainage area of 674km2, average annual discharge of 7.5 m3 s31, sus-pended sediment discharge of 1.92 kg s31, andcorresponding combined annual sediment yieldof 60 600 t (Table 1). The present-day shorelineat the mouths of these rivers includes small deltascharacterized by a series of shore-parallel sandridges and dunes, protecting minor lakes and la-goons behind the present-day shoreline, re£ectingthe wave-dominated hydrological regime of the

western Black Sea coast. The middle-to-lowerreaches of all the rivers were dammed between1956 and 1990, therefore the above-mentionedsediment discharges should be regarded as mini-ma.

3. Geology of northwestern Turkey

The geology of the basement in Thrace (north-western Turkey) is characterized by two distinctrocks: the Istranca Massif and Paleozoic platfor-mal successions (Fig. 3; Okay et al., 1994; Y|lmazet al., 1997). The Istranca Massif occupies north-western Thrace, immediately landward of theBlack Sea coastline, and consists of metamorphicand meta-sedimentary successions of Triassic age,which are unconformably overlain by Jurassic^Cretaceous siliciclastic and volcaniclastic succes-sions (Y|lmaz et al., 1997). In eastern Thrace,

Fig. 3. Simpli¢ed geological map of northwestern Turkey, modi¢ed from Sak|nc' et al. (1999), and the Istanbul and Zonguldakmap sheets of the Geological Maps of Turkey, from Ternek (1964) and Tokay (1964), respectively. Also shown is the regionaldistribution of seismic stratigraphic units 1^5 across the southwestern Black Sea shelf, below the major shelf-crossing unconform-ity K (discussed in text), and the exploration wells Igflneada-1 (I) and Karadeniz-1 (K).

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around the greater Istanbul area, the basementis composed of Ordovician^Carboniferous lime-stones and siliciclastics (Fig. 3; Okay et al.,1994). The basement of the Istanbul Zone, inthe Anatolian segment of western Turkey, is com-posed of meta-sedimentary and siliciclastic succes-sions of Triassic age, unconformably overlainby Cretaceous volcano-sedimentary successions(Y|lmaz et al., 1997). In northwestern Turkey,these basement rocks are unconformably overlainby Eocene limestones and minor siliciclastics (Fig.3; Doust and Ar|kan, 1974; Turgut et al., 1991)which are, in turn, unconformably overlain byOligocene to early Miocene-prograding deltaicsuccessions (Oktay et al., 1992). Early^middleMiocene to Pliocene lacustrine, £uvial and pro-grading deltaic siliciclastics as well as alluvial

fans unconformably overlie the Oligocene to ear-liest Miocene successions (Sak|nc' et al., 1999).Along the coastal region of the Black Sea, allunits are blanketed by a veneer of Quaternarysediments, particularly sands.

4. Data acquisition and approach

During the cruises MAR98 (1998) and MAR00(2000) of the R/V Koca Piri Reis of the Instituteof Marine Sciences and Technology, 14 6 2.5-m-long gravity cores, V2800 line-km of single-chan-nel seismic-re£ection pro¢les and Huntec DeepTow System (DTS) boomer pro¢les, and V2250line-km of 100-kHz side-scan sonar pro¢les werecollected from the southwestern Black Sea shelf

Fig. 4. Index map showing the location of seismic re£ection pro¢les and gravity cores collected during the MAR98 and MAR00cruises of the R/V Koca Piri Reis. Heavy lines in insets a, b and c are seismic pro¢les illustrated in Figs. 5^7, 9, 11^13, 15^20.Circled numbers are gravity cores: cores 1, 2, 3 and 4 are collected during MAR98 cruise whereas the remaining cores are col-lected during the MAR00 cruise. Also shown are the locations of Deep Sea Drilling Project Site 381 (Leg 42), and the explora-tion wells Igflneada-1 (I) and Karadeniz-1 (K).

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and upper slope (Fig. 4). In 1998, V550 line-kmof single-channel pro¢les were acquired using a1580 J sparker source and a 50-element, 9-m-long Benthos hydrophone streamer. In 2000,V2250 km of seismic pro¢les were collected usinga 40-cubic-inch (655 cm3) sleeve-gun source andtwo separate streamers: a 6-m-long, 21-elementNova Scotia Research Foundation Corporation

(NSRFC) streamer, and a 9-m-long, 50-elementBenthos streamer. The Huntec DTS pro¢leswere collected with a 500-J boomer source, re-corded using both a very-high-resolution singleinternal hydrophone and a 21-element, 6-m-longBenthos hydrophone streamer. The Huntec DTSpro¢les have a vertical resolution of 15^30 cm,and locally provide details on sedimentary depos-

Fig. 5. Air-gun seismic re£ection pro¢le showing the seismic stratigraphic units 1^5 identi¢ed in the Black Sea shelf (discussed intext). See Fig. 2 for location.

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Fig. 6. Huntec DTS pro¢les across the southern Black Sea shelf showing gently dipping strata of Unit 2 irregularly truncated bythe regional unconformity, K, and overlain by a thin veneer of subunits 5C and 5D. See Fig. 2 for location.

Table 2Radiocarbon ages reported as uncalibrated conventional 14C dates in yr BP (half-life of 5568 yr; errors represents 68.3% con¢-dence limits), and calibrated calendar years calculated using OxCal (Stuiver et al., 1998a,b) and a marine reservoir correction of415 yr (Marine Reservoir Correction Database, Queens University Belfast, Ireland)

Core # and depth Latitude Longitude Water depth Dated material 14C date Calendar age Lab No.a

(cm) (m) (yr BP) (Cal BP)

MAR98-04 24 41‡27.26PN 29‡16.01PE 3112 Mytilus spp. 5680X 60 6080X 127 TO-7782MAR98-04 104 41‡27.26PN 29‡16.01PE 3112 Mytilus spp. 5780X 60 6165X 143 TO-7783MAR98-04 118 41‡27.26PN 29‡16.01PE 3112 White mussel 33550X 330 N/A TO-7784MAR00-05 60 41‡49.01PN 28‡30.68PE 383 Mytilus spp. 5460X 70 5850X 167 TO-9137MAR00-05 167 41‡49.01PN 28‡30.68PE 383 Cardium spp. 6600X 60 7090X 140 TO-9088MAR00-06 45 41‡50.38PN 28‡37.54PE 3127 Mytilus spp. 2160X 60 2370X 0 TO-9138MAR00-06 124 41‡50.38PN 28‡37.54PE 3127 Mytilus spp. 7770X 70 8200X 147 TO-9089MAR00-08 54 41‡42.16PN 28‡43.32PE 396 Mytilus spp. 5780X 70 6165X 157 TO-9139MAR00-08 116 41‡42.16PN 28‡43.32PE 396 Mytilus spp. 6590X 70 7070X 167 TO-9090MAR00-09 119 41‡42.38PN 29‡06.31PE 3115 Mytilus spp. 5740X 60 6132X 139 TO-9525MAR00-23 170 41‡19.82PN 29‡45.53PE 398 Mytilus spp. 6760X 60 7295X 115 TO-9526

a IsoTrace Radiocarbon Laboratory, Accelerator Mass Spectrometry Facility, University of Toronto. Errors attached to thecalibrated calendar years represent 95% con¢dence limits, but do not account for analytical errors of the 14C dates.

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its up to 50^100 m below the seabed, whereas thesingle channel sleeve gun and sparker pro¢leshave a vertical resolution of V1.5^2.0 m, andimage 300^900 m below the seabed. The HuntecDTS boomer records provide an exceptional rec-ord of sedimentary deposits and erosional surfa-ces generated during and subsequent to the last

low stand of sea level in the southwestern BlackSea. The side-scan sonar data were collected usinga Klein 590/595 system. Navigational ¢xes weretaken at each ¢x (V1.85 km at 6 knots) usinga Geographical Positioning System. Bathymetrywas digitized every 10 min from 12-kHz echo-sounder records. The gravity cores were collected

Fig. 7. Huntec DTS pro¢les across the eastern study area showing the partially exposed surface of Subunit 1A forming pinnaclesand shore-normal-parallel ridges, which are slightly in¢lled with Subunit 5D (discussed in text).

Fig. 8. Schematic illustration of the relationships between seismic^stratigraphic units 1^5 and unconformities K, L, Q and N (dis-cussed in text).

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using a 4-m-long corer with 10 cm internal diam-eter and 400 kg weight. In this paper, thicknessvariations in seismic pro¢les are described in two-way travel time (twt) ; however, a typical intervalvelocity of 1500 m s31 can be used to convert twtto depths below sea level.Eleven shell samples were extracted from sev-

eral levels in six cores and were radiocarbon datedat the Isotrace Radiocarbon Laboratory of theUniversity of Toronto. A full listing of uncor-rected radiocarbon ages and calibrated calendarages (using a reservoir correction of 415 yr) ispresented in Table 2. In this paper, we use onlyuncalibrated ages with no reservoir correction.

5. Seismic stratigraphy of the southwestern BlackSea shelf

Seismic re£ection pro¢les from the southwest-ern Black Sea shelf show ¢ve distinct seismicstratigraphic sequences (terminology from Myersand Milton, 1996) within the uppermost 300^500ms (Figs. 5^7). Units 1 through 5 are separated byfour unconformities, K, L, Q, N ; Unit 1 is underlainby K, Unit 2 by L, and so on (Fig. 8). Units 5through 2 o¥ap toward the shelf edge, so thatUnit 5 occurs landward of Unit 4, Unit 4 occurslandward of Unit 3, and so on to Unit 2, which isrestricted to the shelf edge. Units 5^2 dip north-

Fig. 9. Huntec DTS pro¢les across the western study area showing the folded and faulted strata of Unit 2, the north-dipping un-conformity Q between units 2 and 3, and the nearly undeformed, gently dipping and north-prograding strata of units 3 and 4truncated by the regional unconformity, K, and overlain by a thin veneer of subunits 5B, and 5C. See Fig. 2 for location.

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ward and are all truncated by a more gently in-clined shelf-crossing unconformity called K, whichalso truncates unconformities L, Q and N (Fig. 8).Unconformity K is overlain by Unit 1. The oldestsequence (Unit 5) occurs exclusively on the innerand middle shelf, between the present-day coast-line and the 75-m bathymetric contour (Fig. 3). Itis characterized by a slightly- to moderately-folded and faulted package of acoustically strongre£ectors. The sequence is marked at its top by astrong and regionally distinctive re£ector, K, thatis a major shelf-crossing unconformity (Figs. 5and 6). This unconformity is recognized acrossthe entire width of the southwestern Black Seashelf extending into the shelf^slope break at100^120 m. An equivalent re£ector is also identi-¢ed elsewhere beneath the northern Black Seashelf (e.g. Ryan et al., 1997).Unit 5 is divided into two subunits : 5A exclu-

sively occurs in the easternmost segment of thestudy area, seaward of Cape Pazarbas'| (Fig. 7).It scatters acoustic energy and contains few coher-ent re£ections. The uppermost surface of Subunit5A is partially exposed on the seabed: side-scansonar and Huntec DTS pro¢les in this area showexposed rocky pinnacles organized into shore-nor-

mal parallel ridges (Fig. 7), which are very slightlyin¢lled with deposits of Subunit 1D (discussedbelow). Subunit 5B is characterized by an exten-sively folded and thrust-faulted sedimentary suc-cession. Strata strike east^west, nearly parallel tothe present-day coastline; maximum dips are 5‡.Unit 5 is truncated on its northern margin by agently north-dipping shelf^margin unconformity(N), which itself is truncated by the major shelf-crossing unconformity, K (Fig. 8).Unit 5 is unconformably overlain, along its

northern fringe and across the entire width ofthe shelf, by a folded and faulted north-dippingclinoform package (Unit 4), that is much less de-formed than the underlying Unit 5 (Figs. 5, 8 and9). Unit 4 is truncated at its top by the shelf-cross-ing unconformity, K. This unit is also truncatedon its northern margin by another north-dippingshelf-margin unconformity (Q), which itself istruncated by the major unconformity, K (Fig. 8and 9).Units 3 and 2 are two relatively undeformed,

north-dipping clinoform packages consisting ofacoustically strong re£ectors which show notablelateral continuity (Figs. 5, 8 and 9). These sequen-ces only occur between the mid-shelf and the

Fig. 10. Isopach map in milliseconds of seismic Unit 5 developed above the major shelf-crossing unconformity, K. Also shown byblack dots are the locations of mud volcanoes. Two areas of notable sediment thickness are visible in the western and easternstudy areas. Inset shows the location of Fig. 13, which presents the isopach maps of the individual deltas developed in Subunit5A.

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present-day shelf edge, between water depths of75 and 90 m (Fig. 3). The individual clinoformswithin units 3 and 2 are clearly truncated (at a 5^9‡ angle) by the overlying regional major uncon-formity K. However, in a few pro¢les the oblique-progradational clinoforms and the associated for-mer o¥ap break are observed in both units 3 and2, suggesting that these units represent north-pro-

grading packages, rather than tilted, exhumed anderoded strata. This internal architecture resemblesshelf-edge progradation. The tops of both units 3and 2 are truncated by the regional shelf-crossingunconformity, K.Along the northern fringes of Unit 2, between

V90 m water depth and the present-day shelfbreak, Unit 2 is conformably overlain by Unit 1.

Fig. 11. Air-gun pro¢les across the shelf edge in the western study area showing the shingled, seaward-prograding delta lobes de-veloped within Subunit 5A. See Fig. 2 for location.

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Along its northern margin Unit 3 is separatedfrom Unit 2 by a third north-dipping shelf-edgeunconformity, L (Fig. 5, 8 and 9). The youngestseismic stratigraphic sequence (Unit 1) is a varia-bly re£ective package of acoustically strong andgenerally continuous re£ectors (Figs. 6 and 9). Itunconformably overlies all older units (units 2^5)across the entire southwestern Black Sea shelf.

5.1. Unit 1

Across most of the southwestern Black Seashelf, Unit 1 forms a 2^40-ms-thick veneer ofsediments unconformably deposited over K, ex-cept for the shelf-edge region of the westernmostand easternmost segments of the study area where

Unit 1 reaches thicknesses of s 150 ms and s 75ms, respectively (Fig. 10). On the basis of itsacoustic character and regional distribution,Unit 1 is divided into four subunits : a stronglyre£ective seaward-prograding basal Subunit 1A, astrongly re£ective shingled Subunit 1B, a moder-ately re£ective Subunit 1C and an upper, weak tomoderately re£ective Subunit 1D. Subunit 1A isonly developed along the shelf-edge. The top ofthis subunit is de¢ned by the major unconformity,K (Figs. 10, 11 and 12). Subunit 1B directly over-lies K on the shelf. There is a moderately strongand regionally continuous re£ector (K1) betweensubunits 1B and 1C; the re£ectors of Subunit 1Bshow mild truncation by K1, whereas the re£ectorsof the overlying Subunit 1C show progressive

Fig. 12. Huntec DTS pro¢les across the topset-to-foreset transition of the latest delta lobe v1 developed within Subunit 5A atthe shelf edge in the western study area. See Fig. 2 for location.

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downlap re£ection terminations over K1 (Fig. 13).A weaker, but regionally continuous re£ector (K2)marks the boundary between subunits 1C and 1D.This re£ector drapes over the uppermost re£ectorsof Subunit 1C, whereas the basal re£ectors of theyoungest Subunit 1D show an onlapping-¢ll mor-phology over K2. Both K1 and K2 are minor, butregional unconformities, and are interpreted as alowstand erosional surface and ravinement sur-face, respectively, as discussed below.

5.1.1. Subunit 1ASubunit 1A only occurs along the present-day

shelf edge where it forms a rapidly seaward thick-ening wedge reaching s 175 ms and s 75 ms inthe westernmost and easternmost parts of the

study area, respectively. In the western area thesubunit consists of a number of stacked, laterallyoverlapping, north-prograding packages, charac-terized by distinct sets of oblique-prograding cli-noforms (Figs. 11 and 12). The clinoforms displaya low-angle seaward-dipping upper segment situ-ated immediately beneath the major shelf-crossingunconformity, and a steep middle segment, whichbecomes progressively £at distally. The transitionfrom the upper to middle segments of the clino-forms represents the o¥ap break (Myers and Mil-ton, 1996). Individual wedges are 30^55 ms thickand 1500^3000 m long in the dip direction, andare separated from one another by local uncon-formities, which merge in the landward directionwith the shelf-crossing unconformity, K.

Fig. 13. Huntec DTS pro¢les across the western study area showing a series of prograded bedforms atop the local unconformity,K1. See Fig. 2 for location.

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This seismic architecture resembles that of low-stand shelf-edge delta lobes developed in manyparts of the world’s oceans during glacial periods,as the rivers extended to the shelf-edge (e.g. An-derson et al., 1996; Chiocci et al., 1997; Aksu etal., 1999; Hiscott, 2001). The transition from theupper to middle segments of the oblique-prograd-ing clinoforms (i.e. o¥ap break) represents thetopset-to-foreset transition of a shelf-edge delta.Distribution of the youngest four delta lobes

shows very narrow (3^5 km), but 30^40-km-longisopachs oriented parallel to the present-day shelfedge (Fig. 14). The locus of maximum sedimentthickness migrated seaward during the depositionof each successively younger delta lobe (Fig. 14).The topset-to-foreset transitions (i.e. o¥ap breakof Myers and Milton, 1996) of the deltas v4^v1show a gentle upward climb from V179 ms(3134 m elevation at 1500 m s31) in v4 toV173 ms (3130 m elevation) in v3 to V165 ms

Fig. 14. Detailed isopach maps of delta lobes v1^v4 developed near the shelf edge within Subunit 5A in the western study area.Topset-to-foreset transitions are marked at various locations along the delta fronts. The amount of seaward progradation is illus-trated by the distance between the depocenter axis of v1 and v4. See Fig. 9 for location.

MARGO 3158 4-10-02


(3124 m elevation) in v2 and 155 ms (3116 melevation) in v1. Assuming that the topset-to-fore-set transitions of deltas in the Black Sea typicallyoccur at V10 m water depth and that there islittle subsidence the sea level during the last phaseof progradation of v1 was V106 m below itspresent height.Seaward of the shelf-edge deltas, a number of

stacked, overlapping wedge-shaped and/or lens-shaped bodies are nestled on the uppermost por-tion of the slope (Fig. 11). The individual re£ec-tors within these bodies can be traced up-slopeinto the bottom-set re£ectors of the shelf-edgedeltas (Fig. 11). This architecture resemblesupper-slope fans.In the eastern shelf-edge region, Unit 1 is char-

acterized by a number of stacked, northward-thickening wedges that show an aggradational in-ternal architecture (Fig. 15). These wedges are

separated from one another by minor, local un-conformities and each wedge either onlaps thebedrock in the landward direction or the top ofthe previous progradational wedge. Internally,these wedges show northward oblique clinoformprogradation. Individual wedges are 10^20 msthick and 9^12 km long, notably thinner but lon-ger than those observed in the western shelf-edgeregion.The seismic architecture of Subunit 1A along

the shelf-edge is interpreted to represent lowstandsystems tract, where v4^v1 were deposited duringsuccessive glacially-lowered sea-level settings. Theyoungest delta lobe v1 is deposited during the lastglacial maximum when the sea level was V110 mbelow the present-day level of the Black Sea. Ra-diocarbon dates from cores con¢rm this age as-signment (see below). At that time, the shorelinewas situated near the present-day shelf^slope

Fig. 15. Huntec DTS pro¢les across the eastern shelf edge showing a number of stacked, north-thickening wedges that exhibit anaggradational internal architecture developed within Subunit 5A. These wedges are separated from one another by minor uncon-formities. See Fig. 2 for location.

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break, and small rivers, such as Bulan|k, Pabuc',Kazan, C'ilingos and Kuzulu (west) and Go«ksuand Sakarya (east) were discharging at the shelf-edge.

5.1.2. Subunit 1BSubunit 1B occurs as a number of seaward-pro-

grading imbricate wedge-shaped bodies across aV10-km-wide zone between the 60 m isobathand the present-day shelf edge. These depositsare oriented essentially parallel to the isobaths.In seismic pro¢les they are tens of kilometerslong, 2^6 km wide and have central thicknessesranging from 9 to 15 ms. Internally, these depositsshow seaward-prograding clinoforms, and asym-metrical cross-sectional geometries with widerlandward-dipping sides and narrower seaward-dipping sides (Figs. 13 and 16). These asymmetricwedge-shaped bodies are interpreted as barrier is-lands/beaches on the basis of their geometry, seis-mic facies attributes and similarities with previ-ously described such deposits (e.g. Kraft et al.,1987; Aksu et al., 1999). They are gently shingled

on top of one another, and the crests of succes-sively younger asymmetric wedges are occasion-ally shifted in the seaward direction; however,the successively younger deposits are not at lowerelevation. In some cases, the crests of these imbri-cates are truncated. The seaward-stepping asym-metric wedges are interpreted as progradationalparasequences within a transgressive systemstract, discussed below. Elsewhere, the subunit ischaracterized by thinner planar sheet-like depositswhich are gently shingled seaward.

5.1.3. Subunit 1CAlong the central segment of the western shelf

region, Subunit 1C thickens into three distinctlydi¡erent types of mounds: one type with thecross-sectional geometries, conical shapes, andpiercement relationships characteristic of mudvolcanoes (Figs. 17 and 18), a second type withthe cross-sectional geometries of barrier islands/beaches, and a third type with the morphologicaland cross-sectional characteristics of sedimentridges, sediment waves, and current-generated

Fig. 16. Huntec DTS pro¢les showing a number of imbricate wedge-shaped bodies which consist of seaward-prograding clino-forms that exhibit cross-sectional geometries with longer landward-dipping sides and shorter seaward-dipping sides. See Fig. 2 forlocation.

MARGO 3158 4-10-02


marine bars (Fig. 19). The mud volcanoes werealso imaged using side-scan sonar, have diametersof 200^300 m and rise 20^25 m above the adja-cent sea £oor (Fig. 18). They predominantly occuron the outer shelf in 90^120 m water depths, andare notably absent on the eastern shelf, as well ason the westernmost portion of the study area. Thesediment ridges and waves are 300^900 m longand 3^6 m thick, and are generally oriented par-allel to the shelf edge. The inclined bedding inthese deposits indicates predominantly southeas-terly £ow. In two places on the western shelf,these deposits form large ¢elds of asymmetricbedforms.Across the mid-shelf region of the eastern seg-

ment of the study area, Subunit 1C includes smalleast^west trending, prograded packages which arelenticular in cross section, both in dip and strikepro¢les. Internally, they are characterized by steepseaward-dipping strata on the seaward side andmore gently landward-dipping strata on the land-ward side. They occur in several linear progres-sively landward-stepping clusters which are paral-lel to bathymetric contours; however, thesedeposits are con¢ned to the outer shelf region,separated by intervals where Subunit 1C is absent.The geometry of these lenticular deposits, ori-ented parallel to the isobaths, and their internalarchitecture suggest that they are drownedbeaches and barrier islands. They are interpreted

Fig. 17. Huntec DTS pro¢les across the southwestern Black Sea shelf showing a number of mud volcanoes developed within Sub-unit 5C. See Fig. 2 for location.

MARGO 3158 4-10-02


as progradational parasequences within a trans-gressive systems tract. The clustering of sets ofparallel ridges at progressively shallower waterdepths points to landward migration of the shore-line in distinct steps. The vertical stacking of thesedeposits within each cluster suggests short-dura-tion aggradation where sediment supply musthave kept pace with the sea-level rise. Subse-quently, the shoreline jumped to a new positionfurther landward when the rate of sea-level riseexceeded the rate of sediment supply.Along the inner shelf region, there is a series of

back-stepping, shore-parallel, internally seaward-prograding lenses which are similar to those de-scribed as retrogradational parasequences above,with the exception that they form a nearly con-tinuous zone of shingled, back-stepping depositsover K (Figs. 20^22). The seaward edge of eachdeposit is prism-shaped in cross section in dippro¢les, and stands distinctly above the averageelevation of the deposit. The seaward perimeter ofeach prism-shaped deposit is notably steep andappears degraded both in seismic and side-scansonar pro¢les (Fig. 21). Behind each prism-shapeddeposit the package is characterized by an acous-tically re£ective deposit, which progressively on-laps the landward £ank of the cone, and containsminor internal erosional surfaces (Fig. 22). Tracedlandward, each prism-shaped deposit and its as-sociated onlapping back¢ll package is faithfullyduplicated but at progressively shallower waterdepths (Fig. 20^22). These deposits are also inter-preted as transgressive parasequences within atransgressive systems tract. The triangular depos-its are interpreted as barrier islands with back-barrier washover fans, whereas deposits landwardof the barrier islands are believed to be lagoonaldeposits blanketed by transgressive marine muds.This interpretation is yet to be con¢rmed by cor-ing. The progressive landward migration of thedepositional architecture is interpreted to repre-sent a series of barrier islands, all sequentiallydrowned in-place, associated with a progressivesea-level rise. The internal architecture of eachbarrier complex is remarkably similar to one an-other (Fig. 22). For example, each barrier islandcomplex includes an older acoustically moretransparent (?¢ner-grained) prograded core, a50^75-m-wide younger zone and coarser-grainedclinoforms, and a V2-m-high crestal ridge.The top of Subunit 1C is variably, but clearly

truncated. This truncation is interpreted to haveresulted from extensive reworking and redistribu-tion of sediments by ravinement during the devel-opment of the local unconformity, K2.

5.1.4. Subunit 1DSubunit 1D forms a thin veneer draping all

underlying morphologies and ¢lling residual de-pressions by progressive onlap. It is best devel-

Fig. 18. 100-kHz Klein side-scan sonar pro¢le across thewestern Black Sea shelf showing the plan-view of the mudvolcano illustrated in Huntec DTS pro¢le shown in Fig. 17.See Fig. 2 for location.

MARGO 3158 4-10-02


oped in the nearshore zone, immediately o¡ themouths of small rivers in the westernmost part ofthe study area, such as Bulan|k, Pabuc' and Kazanrivers, as well as west o¡ the mouth of the Sakar-ya River in the easternmost part of the study area.The onset of the deposition of Subunit 1D is in-terpreted as the maximum £ooding surface.

6. Sedimentary data and chronology

Twelve short gravity cores were collected fromthe Black Sea (Fig. 23). Eleven levels in six keycores were radiocarbon dated to provide a chro-

nostratigraphic framework for the seismic re£ec-tion pro¢les (Table 2; Fig. 23).Core MAR98-04 is 150 cm long; it was col-

lected near the shelf-edge (Figs. 4 and 23). HereSubunit 1C overlies the major shelf-crossing un-conformity, K, and Subunit 1D is either extremelythin or absent. The core recovered an approxi-mately 110-cm-thick olive gray clayey mud, withoccasional shelly horizons, underlain by a 40-cm-thick grayish olive mud with frequent horizonscomposed of shell hash. Correlation of the sedi-ments recovered in MAR98-04 with Huntec DTSpro¢les shows that this core recovered an attenu-ated succession representing Subunit 1C, and pe-

Fig. 19. Huntec DTS pro¢les across the western Black Sea shelf showing a number of prograded bedforms with cross-sectionalcharacteristics of sediment ridges, waves, and current-generated marine bars, developed within Subunit 5C. A number of these de-posits are locally pierced by mud volcanoes. Subunit 5D forms a very thin drape over most deposits.

MARGO 3158 4-10-02


netrated below the major shelf-crossing major un-conformity K. Three radiometric dates from thiscore show that the sediments immediately belowthe unconformity, are V33 ka, and that Subunit1C was deposited rapidly since V5.5 ka (Table2).Core MAR00-05 is 172 cm long; it was also

collected near the present-day shelf edge (Figs. 4and 23). Huntec DTS pro¢les around this siteshow that subunits 1C and 1D are very thin (2.5ms thick, or 1.9 m at 1500 m s31), and that thebase of Subunit 1B is at approximately 5.88 ms

(4.41 m) below the seabed. This core was collectedto provide an age for the transition of subunits1C^1B, and, if penetrated, for the base of Subunit1B, immediately following the cessation of shelf-edge delta progradation of the lowermost Subunit1A. The core recovered an approximately 165-cm-thick interval of moderately burrowed olive graymud with rare shells, interrupted by a 10-cm-thickburrowed mud with many scattered shells at 75^85 cm depth in the core. This upper unit overliesan approximately 7-cm-thick, sand-bearing siltymud deposit with abundant (V30%) shells. Cor-

Fig. 20. Huntec DTS pro¢les across the mid-shelf region of the western segment of the study area showing large east^west trend-ing, landward-migrating packages developed within Subunit 5C. The seaward edges of these packages are prism-shaped in dipsections. These deposits are interpreted as retrogradational parasequences within the transgressive systems tract that indicate land-ward migration of the barrier islands in distinct steps. The draping sediments landward of each barrier island represents lagoonalsediments and washover fans. See Fig. 2 for location.

MARGO 3158 4-10-02


relation with Huntec DTS pro¢les suggests thatthe lower sand-bearing sedimentary unit probablyrepresents the transition between subunits 1C and1B. A radiocarbon date of 6.6 ka at 167 cm depthin this core e¡ectively dates the subunit 1C^1Btransition, K1, as slightly younger than 6.6 ka (Ta-ble 2). Seismic pro¢les indicate an additional 2.74m remain between the base of the core and themajor unconformity, K. Two radiocarbon dates inthis core (Table 2) allow the sedimentation ratefor Subunit 1B to be estimated at V93 cm per1000 yr. An extrapolation to the unconformityassuming constant rate of sedimentation, to theunconformity K suggests an age of V9.55 kafor the base of Subunit 1B, corresponding to ces-sation of delta progradation at the shelf edge.

Cores MAR00-06 and MAR00-08 are 131 and126 cm long, respectively; they were collected atthe topset-to-foreset transition of the shelf-edgedeltas in the western part of the study area(Figs. 4 and 23). These cores were collected todate the cessation of delta progradation as sealevel began to rise in this part of the Black Sea.Core MAR00-06 was raised from an area wheresubunits 1B^1D are relatively thin. Here, mostre£ectors show clear convergence toward thecore location, con¢rming a low sedimentationrate. Huntec pro¢les at core site MAR00-06show that the total thickness of subunits 1B^1Dis V2.2 ms (1.65 m). The core recovered V49 cmof color-banded greenish-gray and black muds,overlying 82 cm of greenish-gray muds with scat-

Fig. 21. Huntec DTS pro¢le showing the detailed image of a barrier island (top) and the corresponding 100-kHz Klein side-scansonar pro¢le. See Figs. 4 and 20 for location.

MARGO 3158 4-10-02


tered shells and shell-rich layers. A radiocarbondate of 7.77 ka was obtained on a Mytilus valveextracted at 124 cm depth in this core (Table 2).Core MAR00-06 nearly recovered the entire Sub-unit 1B; however, an additional V40 cm of sedi-ments still remain undated between the bottom ofthe core and the major shelf-crossing unconform-ity, K. A second radiocarbon date of 2.16 ka at 45cm depth in this core suggests a sedimentationrate of V15 cm per 1000 yr for the core site.Linear extrapolation assuming a constant sedi-mentation rates suggests that the base of Subunit1B may be as old as V10 500 yr.Huntec DTS pro¢les around core site MAR00-

08 show that subunits 1C and 1B have thicknessesof 0.5 and 4.8 ms (0.38 m and 3.62 m), with K

situated at 5.3 ms (4.0 m) below the sea£oor. Thiscore recovered a 126-cm-thick veneer of moder-ately burrowed greenish-gray muds, with frequentshells, and shell-rich layers. Correlation with the

seismic pro¢les suggests that core MAR00-08 pe-netrated the local unconformity (K1) separatingsubunits 1B and 1C. A radiocarbon date of 6.59ka on a Mytilus valve at 116 cm depth in this core(Table 2), still V106 cm above K, is consistentwith the V9.55 and 10.5 ka assigned to this un-conformity in cores MAR00-05 and MAR00-06,respectively. However, the core also failed to fullyrecover Subunit 1B, and an additional 2.74 m ofsediments remain undated between the base thecore and the base of Subunit 1B. Two radiocar-bon dates in this core (Table 2) allow a sedimen-tation rate of 76 cm per 1000 yr to be estimatedfor the remainder of Subunit 1B, leading to aprojected age of 10.3 ka for the base of Subunit1B, if constant sedimentation rate is assumed(Fig. 23).Cores MAR00-09 and MAR00-23 are collected

in a mid-shelf setting away from the shelf-edgedeltas, to date the cessation of shelf-edge progra-

Fig. 22. Huntec DTS pro¢les showing the similarities in sedimentary architecture of three barrier island lagoon complexes. SeeFigs. 4 and 20 for location.

MARGO 3158 4-10-02


Fig. 23. Summary lithostratigraphy and seismic stratigraphy of the cores collected from the Black Sea. Arrows with numbers in-dicate radiocarbon ages in ka (Table 2). See Fig. 2 for location.

MARGO 3158 4-10-02


dation associated with the post-glacial sea-levelrise in the southwestern Black Sea. Huntec DTSpro¢les show that at the core site MAR00-09,Subunit 1D is either very thin or absent and 1Cis V215 cm thick, resting over the shelf-crossingunconformity, K. The core recovered a 124-cm-thick succession of shell-bearing bioturbatedmuds. A radiocarbon date 5.74 ka was obtainedon a Mytilus valve extracted at 119 cm depth inthis core (Table 2). Linear extrapolations assum-ing a constant sedimentation rate suggest that theoldest sediments above the unconformity areV10.32 ka. Huntec pro¢les show that at thecore site MAR00-23 the total thickness of sub-units 1B^1D is V2.5 m. The core recoveredV170 cm of color-banded greenish-gray andblack muds with scattered shells and shell-richlayers. A radiocarbon date of 6.76 ka was ob-tained on a Mytilus valve extracted at 170 cmdepth in this core (Table 2). Linear extrapolationassuming a constant sedimentation rate suggeststhat the base of Subunit 1B may be as old asV9.94 ka.On the basis of the several radiocarbon dates,

its stratigraphic position above the regional shelf-crossing unconformity K, and its acoustic similar-ities with previously dated successions nearby inthe northern Marmara Sea (Evans et al., 1989),the youngest Unit 1 is assigned a last glacial toHolocene age, with K representing the uncon-formity developed during the last glacial low-stand. The age extrapolations below coring depthscon¢rm that the lowstand systems tract depositsof Subunit 1A represent the latest phase of deltaprogradation along the present-day shelf-edgeduring the last glacial period (i.e. oxygen isotopicstage 2), immediately prior to the post-glacialtransgression (i.e. isotopic stage 2^1 transition).The forced-regressive, progradational and aggra-dational deposits of subunits 1B^D, respectivelyare all deposited during the last V10 500 yr.The post-K sediments on southwestern Black

Sea shelf are overwhelmingly dominated bymuds, presumably supplied by large rivers to thenorthwest of the study area, such as Danube, aswell as various small local rivers. However, theisopach map of Unit 1 and radiocarbon datedcores show that post-glacial sediments are re-

markably thin (1^5 ms; 0.75^3.75 m) over thesouthwestern shelf and that signi¢cant accumu-lations of Unit 1 only occur at the shelf edge asprograded deltas and near the mouths of present-day small rivers. Several coring attempts havebeen made on the central southwestern shelf inwater depths of 80^90 m where Unit 1 is 1^2 msthick, and forms irregularly preserved sheet-likedeposits above the shelf-crossing unconformityK. These cores only recovered a thin veneer ofwell-rounded and sorted mud-bearing gravellysand, which resembles lag deposits (Plate 1). Themud fraction is likely not primary, and may evenbe a result of mixing of sands interbedded withmuds during coring. The wave-dominated hydro-dynamic setting of the Black Sea prevents the de-position of signi¢cant amounts of sediment inwater depths less than V70 m, except for theregions o¡ the mouths of rivers. At shallowerdepths sediments are largely winnowed leavingshell-rich horizons (?shell-hash) interbedded withbioturbated muds. The lag deposits, and paucityof any appreciable sediment thickness on the shelfsuggest that noticeable sediment accumulationonly begins when the water depth exceeds 70^75m, so that reworking by storm waves becomesnegligible. Even the extrapolated estimates ofV10.5 ka for the beginning of post-glacial sedi-mentation along the southwestern Black Sea shelfmust, therefore, be regarded as minimum esti-mates because sedimentation may have been de-layed at these core sites until the water depth wass 70 m, perhaps thousands of years after aban-donment of the lowstand deltas.There are two exploration wells in southwestern

Black Sea which provide the chronology for units2^5 (Fig. 4). Karadeniz-1 and Igflneada-1 weredrilled at 79 and 85 m water depth, to sub-seadepths of 2597 and 3118 m, respectively (Can,1996). Karadeniz-1 recovered a very thin veneerof unconsolidated muds of Quaternary age, un-conformably overlying a 107-m-thick package ofmudstone interbedded with shelly horizons ofPliocene age which, in turn, unconformably over-lies 1386 m of prograded deltaic mudstones, sand-stones and conglomerates of late Oligocene^earlyMiocene to middle Miocene age (Can, 1996). Thewell further penetrated into a 963-m-thick Paleo-

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Plate I.

MARGO 3158 4-10-02


ceneÔligocene shale^sandstone sequence, uncon-formably overlying 62 m of pillow lavas, tu¡s andred micritic limestones of late Cretaceous age(Can, 1996). The Igflneada-1 well recovered a140-m-thick north-prograded Quaternary succes-sion, unconformably overlying a 284-m-thickPliocene shallow marine succession of mudstoneswith shelly horizons, which then unconformablyoverlies 1380 m of prograded deltaic mudstones,sandstones and conglomerates of late Oligoceneêarly Miocene to middle Miocene age (Can,1996). The well further recovered a 1228-m suc-cession of upper Eocene to lower Oligocene shalesand turbidites.On the basis of biostratigraphic data from the

Igflneada-1 and Karadeniz-1 wells (Figs. 3 and 4;Can, 1996) and their seismic stratigraphic charac-ter, units 2 and 3 are interpreted as north-pro-grading deltaic successions of Plio-Quaternaryand Mio-Pliocene age, respectively. On the basisof its seismic character (e.g. Can, 1996) and strati-graphic position unconformably beneath the Mio-Pliocene succession of Unit 3, Unit 4 is inferred tobe Eoceneêarly Miocene in age. Subunits 5B and5A are correlated with the Mesozoic (Cretaceous)sedimentary and volcano-sedimentary successions(Can, 1996; Y|lmaz et al., 1997).

7. Chronology and history of delta progradation

There is no direct chronological control for theprograding delta successions observed along thesouthwestern Black Sea shelf. However, a ¢rst-order chronology can be established through sedi-ment budget calculations using present-day sedi-ment discharges of the Bulan|k, Pabuc', Kazan,C'ilingos and Kuzulu rivers (Table 1).It has long been recognized that delta progra-

dation onto rapidly subsiding continental shelvesof the eastern Mediterranean Sea during Quater-nary glacio-eustatic sea-level oscillations produced

a series of stacked deltaic sequences (e.g. Aksu etal., 1992a,b, 1999). These stacked deltas are sep-arated by major shelf-crossing unconformities de-veloped near the end of glacial isotopic stages2^4, 6, 8, and 10 when the shelves were exposedto subaerial erosion (Piper and Aksu, 1992), withthe subsequent transgressions at global isotopicstage boundaries 2/1, 6/5, 8/7, and 10/9 (Aksu etal., 1992b). Prograded deltas along the southwest-ern Black Sea shelf do not show this depositionalarchitecture; instead, the present-day shelf edge ischaracterized by a number of notably elongated,shoreline-parallel delta lobes which are gentlyshingled seaward (Figs. 5 and 14). One majorshelf-crossing unconformity, K, is present abovethese deltas. This depositional architecture is instark contrast with the stacked deltas of the east-ern Mediterranean Sea and shows that negligiblerates of subsidence along the southwestern BlackSea shelf created little or no accommodationspace during the deposition of these delta lobesand that sediments contributed by rivers were al-most entirely used for shelf-edge progradation.The present-day suspended sediment discharge

of the Bulan|k, Pabuc', Kazan, C'ilingos and Ku-zulu rivers is 29 930 t (Table 1) which, assumingthat the bedload discharge constitutes V10% ofthe total sediment yield (Kukal, 1971, p. 35),translates to a total annual sediment yield of ap-proximately 32 900 t.The total volume of sediments deposited within

the aggregate deltas v1^v4, developed below K, iscalculated from the isopach maps to be V0.34km3. An additional 0.09 km3 are calculated tobe stored within the sandbars and/or barrier is-lands, bringing the total aggregate volume toV0.43 km3 or 1.6U1010 t assuming a porosityof V40% (average near-surface value in mixedsands and muds, from Hegarty et al., 1988), anda solids density of approximately 2.65 g cm33.Assuming that (i) the present-day combined sedi-ment yield of the Bulan|k, Pabuc', Kazan, C'ilingos

Plate I. Grain-size distribution of a lag deposit from southwestern Black Sea shelf at V85 m water depth (core MAR00-12;41‡25.895PN and 29‡00.830PE). Numbers on dishes represent phi scale (4P=63 Wm, 3P=125 Wm, 2P=250 Wm, 1P=500 Wm,0P=1000 Wm, 31P=2000 Wm, 32P=4000 Wm, 33P=8000 Wm). Note the dominance of the sample by well-rounded beach andcoarse sand and the dramatic decrease in medium-¢ne sand. Silt and clay constituted less that 10%.

MARGO 3158 4-10-02


and Kuzulu rivers is representative of their lateQuaternary yield, and (ii) approximately 60% ofthe sediment yield is used for delta progradation(Kukal, 1971, p. 38), with the rest being dispersedthroughout the southwestern Black Sea, the timerequired for the development of deltas v1 throughv4 is calculated to beV470 000 yr, with v1, v2, v3and v4 representing V131 000, 119 000, 124 000and 96 000 yr of progradation, respectively. This¢rst-order calculation suggests that v1, v2, v3 andv4 were deposited during the global glacial oxy-gen isotopic stages 2^4, 6, 8 and 10, respectively.They could not possibly have all formed by auto-cyclic delta^lobe switching during the last glacialmaximum lowstand (isotopic stage 2) because ofthe large total volume of sediments present. Lon-ger cores and radiometric dates are needed toprovide an accurate chronology for these pro-graded delta successions.

8. Discussion

The internal seismic architecture and the re-gional distribution patterns of seismic units 2^4suggest a protracted history of shelf-edge progra-dation under reasonably stable shelf conditionswith sea-level variations restricted toV100^150 m.The distinct oblique-prograding clinoform seismicarchitecture of units 2 and 3 clearly indicatethat little tectonic subsidence occurred along thesouthwestern Black Sea shelf since the Miocene,so that sea-level variations alone controlled theavailability of accommodation space. The gentleseaward dip of the shelf pro¢le is believed to re-£ect repeated phases of erosion through a numberof episodes of falling sea level, rather than £exuralbending under sediment load. Being an enclosedocean basin since at least the Miocene (Kvasos,1983), the sea level in the Black Sea must havealways been controlled by the interplay betweenthe fresh water discharge of major rivers enteringthe Black Sea and out£ow into the eastern Med-iterranean Sea via the present-day Strait of Bos-phorus and similar former straits. These riversincluded the Danube, Dniester, Dnieper, SouthernBug, and Don rivers, as well as the Volga Riverwhen the Black Sea was connected with the Cas-

pian Sea via the Manych-Kuma shoals (Pirazzoli,1996). The evolution and position of the Strait ofBosphorus is intrinsically controlled by the dex-tral North Anatolian Fault Zone (Go«kas'an et al.,1997). The Strait of Bosphorus is believed to be ayoung feature, being in existence for only the lastV100 000 yr (Go«kas'an et al., 1997; Oktay et al.,2002). There is compelling ¢eld evidence that pri-or to the opening of the Strait of Bosphorus anearlier strait connected the Black Sea to the east-ern Mediterranean Sea, situated further to theeast near the mouth of the present-day SakaryaRiver: this now-buried channel is referred to asthe ‘Sakarya Bosphorus’ (Pfannensteil, 1944).Unit 1 corresponds to the late Pleistocene phase

of deposition in this protracted history. Subunit1A along the shelf-edge represents the lowstandsystems tract, with four distinct delta lobes v4^v1 deposited during successive glacially loweredsea-level settings. The youngest delta lobe v1 in1A is deposited during the last glacial maximumwhen the sea level was V110 m below thepresent-day level of the Black Sea. Sediments inv1 and the overlying subunits 1B^1D represent asingle cycle of sedimentation during a signi¢cantfall and subsequent rise of sea level during the lastV20 000 yr or so. On the shelf Unit 1 is boundedbelow by a non-marine erosional surface; andabove by a maximum £ooding surface; thus, itis half of a seismic stratigraphic sequence (e.g.Myers and Milton, 1996). Subunits 1B^1D arethree-dimensional seismic packages which consistof conformable re£ections bounded by relativelyminor unconformity surfaces, where re£ectionsterminate by toplap, downlap, and onlap. There-fore, they also represent distinct systems tracts.On the basis of internal stratigraphic architectureand external geometries, subunits 1B and 1Care interpreted as the transgressive systems tract,and Subunit 1D is interpreted as the highstandsystems tract. The lowstand systems tract depos-its (v1^v4 of Subunit 1A) consist of a set ofoverlapping and seaward-prograding shelf-edgewedges deposited during lowstands and the sub-sequent initial rises of sea level during the latePleistocene. These shelf-edge wedges are best de-veloped along the westernmost and easternmostsegments of the study area, o¡ the mouths of

MARGO 3158 4-10-02


rivers. The transgressive systems tract depositsconsist of a set of shingled, elongate, back-step-ping, and internally seaward-prograding parase-quences, deposited during a phase of rapid sea-level rise. The highstand system tract deposits in-clude (i) a number of prograded sediment bodies(including barrier islands, beach deposits) and (ii)a thin veneer of seismically transparent mudswhich onlap the £anks of older highs.During the peak of the last glacial maximum,

some 20^18 ka, the level of the Black Sea waslower than the breach depth of the Strait of Bos-phorus; however, there is no consensus regardingthe amount of sea-level lowering. For example,while Ryan et al. (1997) and Winguth et al.(2000) argued that the Black Sea level was at anelevation of 3150 m, Kaplin and Shcherbakov(1986) and Julian et al. (1987) indicated that itwas V390 m, whereas Pirazzoli (1996) arguedfor a lowstand of 3110 m between 18 and 17ka (Fig. 24). The seismic data presented in thispaper clearly show that the topset-to-foreset tran-sition of the latest shelf-edge delta (i.e. v1), depos-ited during the latest period of the last glacialmaximum, immediately prior to the post-glacialtransgression occurs at V115 m below present-day sea-level. The topset-to-foreset transitions ofpresent-day deltas along the southwestern BlackSea occur at V5 m water depth, suggesting thatthe sea level during the last glacial maximum wasclose to 3110 m elevation. During this period, theentire southwestern Black Sea shelf was subareally

exposed, and the shoreline was located at or nearthe present-day shelf edge where small rivers, suchas Bulan|k, Pabuc', Kazan, C'ilingos and Kuzuluin the west and the Riva, Go«ksu and Sakarya inthe east, emptied onto the upper slope, possiblydirectly into submarine canyons, such as thepresent-day Sakarya River. Present-day canyonheads were then situated in the coastal wavezone, which promoted increased shelf erosionand mass wasting. Along the northern and north-western regions of the Black Sea, south of CrimeaPeninsula and east of Danube delta, respectively,the shelf was over-deepened by rapid tectonic sub-sidence, and a narrow shelf probably existed dur-ing the last lowstand of sea level at the glacialmaximum (Mihailescu, 1989). The map patternof the present-day valleys of the Bulan|k, Pabuc',Kazan, C'ilingos and Kuzulu rivers in the westernpart of the study area (Fig. 2) suggests that theymight have been of the tributaries of a single larg-er river, which, following the post-glacial trans-gression, became drowned so that these formertributaries are now separated. If true, then theformer main river valley must now be buried be-neath the present-day shelf. Indeed, high-resolu-tion seismic re£ection pro¢les along the north-western segment of the study area, seaward ofthe mouths of these small rivers, and isopachmap of Unit 1 image a large river valley whichis completely ¢lled with sediments of Unit 1 (Fig.10).Glacio-eustatic sea-level curves for the world

ocean suggest that the post-Weichselian sea levelstarted to rise at V18 ka, associated with thedisintegration of continental ice sheets (Chappelland Shackleton, 1986; Fairbanks, 1989). Pirazzoli(1996) similarly suggests that the level of theBlack Sea started to rise from its low of 3110 mat V17 ka, crossed 3100 m at V15 ka reachingits present level V5 ka (Fig. 24). Two majorinterruptions are detectable in this otherwise con-tinuous sea-level rise: between 12 and 10 ka BlackSea level stalled at 340 m, and between 9 and 8 kathe sea level remained constant at about 320 mbefore continuing its rise (Fig. 24). The plateauxon the Pirazzoli (1996) curve for the Black Seacan readily be explained by our conclusions re-garding the pace of the transgression and connec-

Fig. 24. Post-glacial sea-level curve for the Black Sea (Sere-bryanny, 1982; Pirazzoli, 1996).

MARGO 3158 4-10-02


tions across the Strait of Bosphorus. Speci¢cally,the Black Sea level would have stalled at 340 mbecause this was the spill point into the MarmaraSea at V10 ka, when the global ocean was stilllower than the Black Sea level. Only after theMarmara Sea (by now connected to the Mediter-ranean) reached 340 m elevation could the BlackSea continue to rise in synchroneity with the glob-al ocean. However, the data presented in this pa-per suggest that the level of the Black Sea re-mained at V3110 m elevation until V11^10.5ka. Considering the fact that the sources of major£uvial systems discharging into the Black Sea aresituated in central Europe, this asynchroneity be-tween the land-locked Black Sea and the globalsea level appears peculiar. Why might the rise ofthe Black Sea have been delayed? Or is it de-layed?The climate in central Europe remained very

cold and dry from the peak of the late glacialmaximum until approximately 12^13 ka (Prenticeet al., 1992; Guiot et al., 1993; Harrison et al.,1993, 1996). During this interval, the dischargesof the present-day major rivers which drain cen-tral-eastern Europe must have been substantiallyreduced, tilting the water balance toward evapo-ration and maintaining a lowered sea level in theBlack Sea. The transition from the late Weichse-lian glacial to Holocene was marked by a notice-able warming an increase in precipitation allacross the Europe and the entire Mediterraneanregion starting as early as 12 ka (Harrison et al.,1996). Similar wetter conditions are also recordedin Europe, but with an V1500 yr delay. The dra-matic retreat of the Scandinavian ice sheet culmi-nating at V9.5 ka and its disappearance at 8.5^7.5 ka allowed the progressive establishment of ahighly meridional atmospheric circulation overEurope, promoting wetter conditions (Prentice etal., 1992; Guiot et al., 1993; Harrison et al., 1993,1996). Increased pluviality over Europe is believedto have caused an increase the discharge of riversentering the Black Sea, which was rapidly ¢lledfrom its glacial maximum lowstand to the breachdepth of the Strait of Bosphorus. The volume ofthe Black Sea basin between the present-day sur-face and the 110 m isobath is V54 000 km3. Itwould have taken less than 200 yr to re¢ll this

volume with today’s mainly river-derived net out-£ow (350 km3 yr31) from the Black Sea.It is also possible that the Black Sea level

started to rise V17 ka as suggested by Pirazzoli(1996). This sea-level rise must have been rela-tively slow because of the climatic reasons ex-plained above. For the rise to have started earlierat 17^15 ka as proposed by Pirazzoli (1996), wewould have to propose an extended period ofnon-deposition at the shelf-edge where our coresand chronology were obtained. The wave-domi-nated shelf regime in southwestern Black Seaand the associated longshore currents prob-ably prevented the deposition of any signi¢cantamount of transgressive muds across the shelf-edge until the sea level reached 340 m (waterdepth of V70 m), when reworking by stormwaves became negligible. The extrapolated agesof 11^10.5 ka for the base of the transgressivemuds over the shelf-edge deltas would date thecessation of wave reworking and the onset ofmud deposition during the early^middle part ofthe Holocene transgression.The re¢lling of the Black Sea was probably rel-

atively rapid, and during this early sea-level risedelta progradation ceased along the shelf edgewhen the rate of sea-level rise exceeded the rateof sediment supply. Thus, deltas were abandonedand the shoreline began moving landward. Thecore data only crudely constrain the timing ofthis delta abandonment; however, detailed seismicstratigraphic analysis, and several radiocarbondates allow linear extrapolation to suggest thatthe cessation of delta progradation occurred be-fore 11^10.5 ka, possibly as old as 15^17 ka assuggested by Pirazzoli (1996). This time frame isfurther supported by the age of a south-prograd-ing delta at the southern exit of the Strait of Bos-phorus where it enters the Marmara Sea (Hiscottet al., 2002). The youngest delta at the southernend of the strait formed between V10 and 6.5 ka,just after the sea level in the Black Sea rose tobreach the Strait of Bosphorus, and water beganvigorously £owing into the Marmara Sea. Duringthe subsequent rapid sea-level rise, sediments car-ried by the rivers as well as supplied by coastalravinement were redistributed by waves andstorm-generated ocean currents to form the ob-

MARGO 3158 4-10-02


served back-stepping, and internally seaward-prograding parasequences of the transgressivesystems tract. Although the sea-level rise was rap-id, it was not geologically instantaneous as sug-gested by Ryan et al. (1997); transgressive systemstract deposits could not have formed along thesouthwestern Black Sea shelf during the cata-strophic sea-level rise suggested by Ryan et al.(1997).The chronology of the events revealed by the

seismic and core data discussed in this paper isinconsistent with the conclusions of Ryan et al.(1997). Ryan et al. (1997) suggested that the post-glacial sea level rose suddenly at V7.15 ka whenthe Mediterranean Sea breached the Strait of Bos-phorus, catastrophically re-¢lling the Black Seabasin. The radiocarbon dates for the uppermostsediments of Subunit 1B in cores MAR00-05, -06and -08 suggest that the sea-level rise began wellbefore 7.77 ka. Linear extrapolation using con-stant sedimentation rates suggests that transgres-sion began following the abandonment of shelf-edge deltas some 11^10.5 ka, and well beforethat in order to account for the V70 m waterdepth required to get deposition (Pirazzoli,1996). The dating of delta progradation at thesouthern end of Bosphorus Strait, shown by His-cott et al. (2002) to have been fed by over£owfrom the Black Sea, requires that the Black Seareached an elevation of 340 m or shallower byV10 ka.The stratigraphic architecture of the shelf-edge

deltas, with several shingled delta lobes, suggeststhat the sea level in the Black Sea fell severaltimes during the Quaternary. The similar eleva-tions of the topset-to-foreset transitions in thesedeltas show that (i) there has been little tectonicsubsidence across the southwestern Black Seashelf during the Quaternary, (ii) nearly all accom-modation space on the shelf was created duringthe sea-level rises associated with interglacial peri-ods, and (iii) the magnitude of the sea-level low-ering for the latest four to ¢ve glacial intervalswas similar, ranging between 3110 and 3120 mbelow the present level. The absence of any no-ticeable thickness of late Quaternary sedimentsacross the entire shelf, and the merging of thelocal unconformities between individual delta

lobes with the major shelf-crossing unconformity,K, suggest that the entire shelf region became sub-aerially exposed during successive sea-level lows.Exhumation during these periods removed allsediments deposited during the previous high-stand interval.

9. Conclusions

(1) High-resolution seismic re£ection pro¢lesfrom the southwestern Black Sea shelf show ¢vedistinct seismic stratigraphic sequences, separatedfrom one another by erosional unconformities.Unit 5 is a slightly to moderately folded andfaulted package that occurs between the present-day coastline and the 75-m bathymetric contour,and represents Mesozoic metamorphic and volca-no-sedimentary successions. Unit 4 is a folded andfaulted north-dipping clinoform package, whichshows less deformation than the underlying Unit5. It occurs in mid-shelf regions, and representsEocene limestones and minor siliciclastics. Units 3and 2 are relatively undeformed, north-dippingclinoform packages. They only occur betweenthe mid-shelf and the present-day shelf edge, atwater depths of 75 and 90 m. Units 3 and 2 rep-resent Oligocene^early Miocene and early^middleMiocene to Pliocene-prograding deltaic, £uvialand lacustrine successions. Unit 1 is a variablyre£ective package of acoustically strong and gen-erally continuous re£ectors. It is late glacial toHolocene in age and unconformably overlies units2^5 across the entire southwestern Black Seashelf.(2) Unit 1 is divided into four subunits. On the

basis of internal stratigraphic architecture and ex-ternal geometry, subunit 1A is interpreted as anamalgamation of four lowstand systems tracts,whereas 1B and 1C are interpreted as a transgres-sive systems tract associated with the last Glacial^Holocene sea level rise, and Subunit 1D is inter-preted as a late Holocene highstand systems tract.The lowstand systems tract deposits consist of aset of overlapping and seaward-prograding shelf-edge wedges deposited during the lowstand andthe subsequent initial rise of sea level. Theseshelf-edge wedges are best developed along the

MARGO 3158 4-10-02


westernmost and easternmost segments of thestudy area, o¡ the mouths of rivers. The trans-gressive systems tract deposits consist of a set ofshingled, elongate, back-stepping, and internal-ly seaward-prograding parasequences, depositedduring a phase of rapid sea-level rise (includingbarrier islands, beach deposits). The highstandsystem tract deposits include a thin veneer of seis-mically transparent muds showing onlap onto the£anks of older sedimentary features (e.g. drownedbarrier islands).(3) The seismic re£ection pro¢les and core data

show that the sedimentary architecture of the lateQuaternary deposits (Unit 1) from the southwest-ern Black Sea shelf records sedimentation duringthe progressive fall of local sea level leading to thelast glacial maximum at V20 ka, followed by arise of sea level associated with increased riverineinput beginning at V11 ka. These data do notsupport the catastrophic re¢lling of the BlackSea by waters from the Mediterranean Sea at7.1 ka postulated by Ryan et al. (1997) andRyan and Pitman (1999).

Acknowledgements

We thank Prof. Dr. Erol Izdar, the Director ofthe Piri Reis Foundation for Maritime and Ma-rine Resources Development and Education, Iz-mir, Turkey, and Prof. Dr. Orhan Uslu, the Di-rector of the Institute of Marine Sciences andTechnology, Dokuz Eylu« l University, for theirsupport and encouragement. We extend our spe-cial thanks to the o⁄cers and crew of the R/VKoca Piri Reis for their assistance in data acqui-sition, in particular Captain Mehmet Oº zsayg|l|and the Chief Engineer Oº mer C'ubuk. We ac-knowledge research and ship-time funds fromthe Natural Sciences and Engineering ResearchCouncil of Canada (NSERC) to A.E.A. andR.N.H., travel funds from the Dean of Science,Memorial University of Newfoundland, and aspecial grant from the Piri Reis Foundation forMaritime and Marine Resources Developmentand Education. We acknowledge Phil Weaverand Mark De Batist for their critically commentson the manuscript.

References

Aksu, A.E., Ulugfl, A., Piper, D.J.W., Konuk, Y.T., Turgut, S.,1992a. Quaternary sedimentary history of Adana, Ciliciaand Iskenderun Basins, northeastern Mediterranean Sea.Mar. Geol. 104, 55^71.

Aksu, A.E., Calon, T.J., Piper, D.J.W., Turgut, S., Izdar,E.K., 1992b. Architecture of late orogenic basins in the east-ern Mediterranean Sea. Tectonophysics 210, 191^213.

Aksu, A.E., Yas'ar, D., Mudie, P.J., 1995a. Paleoclimatic andpaleoceanographic conditions leading to development ofsapropel layer S1 in the Aegean Sea basins. Palaeogeogr.Palaeoclimatol. Palaeoecol. 116, 71^101.

Aksu, A.E., Yas'ar, D., Mudie, P.J., Gillespie, H., 1995b. Lateglacial-Holocene paleoclimatic and paleoceanographic evo-lution of the Aegean Sea: micropaleontological and stableisotopic evidence. Mar. Micropaleontol. 25, 1^28.

Aksu, A.E., Hiscott, R.N., Yas'ar, D., 1999. Oscillating Qua-ternary water levels of the Marmara Sea and vigorous out-£ow into the Aegean Sea from the Marmara Sea-Black Seadrainage corridor. Mar. Geol. 153, 275^302.

Aksu, A.E., Hiscott, R.N., Kaminski, M.A., Mudie, P.J., Gil-lespie, H., Abrajano, T., Yas'ar, D., 2002. Last glacial ^Holocene paleoceanography of the Black Sea and MarmaraSea: stable isotopic, foraminiferal and coccolith evidence.Mar. Geol. 190, S0025-3227(02)00345-6.

Anderson, J.B., Abdulah, K., Sarzalejo, S., Siringan, F., Tho-mas, M.A., 1996. Late Quaternary sedimentation and high-resolution sequence stratigraphy of the east Texas shelf. In:De Batist, M., Jacobs, P. (Eds.), Geology of SiliciclasticShelf Seas. Geological Society London, Special Publication117, pp. 95^124.

Ballard, R.D., Coleman, D.F., Rosenberg, G.D., 2000. Fur-ther evidence of abrupt Holocene drowning of the Black Seashelf. Mar. Geol. 170, 253^261.

Bes'iktepe, S'., Sur, H.I., Oº zsoy, E., Latif, M.A., Ogfluz, T.,Uº nlu«ata, Uº ., 1994. The circulation and hydrography of theMarmara Sea. Prog. Oceanogr. 34, 285^334.

Bogdanova, C., 1969. Seasonal £uctuations in the in£ow andthe distribution of the Mediterranean waters in the BlackSea. In: Fomin, L.M. (Ed.), Basic Features of the Geolog-ical Structure, the Hydrological Regime and Biology of theMediterranean Sea. Academy of Science, USSR, Moscow.English translation by Institute of Modern Languages,Washington, DC, pp. 131^139.

Brown, D., 1999. ‘Great Flood’ Theory passes science test:Dam! Where did all that water come from. AAPG Explorer,April, pp. 47^67.

Can, E., 1996. Tectonic Evolution of the Southwestern BlackSea Margin, o¡shore Turkey. Unpublished M.Sci. Thesis.Texas ApM University, 88 pp.

Chappell, J., Shackleton, N.J., 1986. Oxygen isotopes and sealevel. Nature 324, 137^140.

Chiocci, F.L., Ercilla, G., Torres, J., 1997. Stratal architectureof western Mediterranean margins as the result of the stack-ing of Quaternary lowstand deposits below ‘glaciao-eustatic£uctuation base’. Sediment. Geol. 112, 195^217.

MARGO 3158 4-10-02


Doust, H., Ar|kan, Y., 1974. The Geology of the Thrace basin.In: Proceedings of the 2nd Petroleum Congress and Exhibi-tion of Turkey, Ankara. Association of Turkish PetroleumGeologists, pp. 119^136.

EIE, 1991, Elektrik Isleri Etu«d Idaresi Genel Direkto«rlu«gu« ,1991 Water Year Discharges, 209 pp.

Evans, G., Erten, H., Alavri, S.N., Von Gunten, H.R., Ergin,M., 1989. Super¢cial deep-water sediments of the easternMarmara basin. Geo-Mar. Lett. 9, 27^36.

Fairbanks, R.G., 1989. A 17 000-year glacio-eustatic sea levelrecord: in£uence of glacial melting rates on the YoungerDryas event and deep-ocean circulation. Nature 342, 637^642.

Go«kas'an, E., Demirbagfl, E., Oktay, F.Y., Ecevitogfllu, B.,S'ims'ek, M., Yu«ce, H., 1997. On the origin of the Bosphorus.Mar. Geol. 140, 183^199.

Guiot, J., Harrison, S., Prentice, I.C., 1993. Reconstruction ofHolocene precipitation patterns in Europe using pollen andlake-level data. Quat. Res. 40, 139^149.

Harrison, S.P., Prentice, I.C., Guiot, J., 1993. Climatic con-trols of Holocene lake-level changes in Europe. Clim. Dyn.8, 189^200.

Harrison, S.P., Yu, G., Tarasov, P., 1996. Late Quaternarylake-level record from northern Eurasia. Quat. Res. 45,138^159.

Hegarty, K.A., Weisel, J.K., Mutter, J.C., 1988. Subsidencehistory of the Australia’s southern margin: constraints onbasin models. Am. Assoc. Pet. Geol. Bull. 72, 615^633.

Hiscott, R.N., 2001. Depositional sequences controlled by highrates of sediment supply, sea-level variations, and growthfaulting: the Quaternary Baram Delta of northwestern Bor-neo. Mar. Geol. 175, 67^102.

Hiscott, R.N., Aksu, A.E., 2002. Late Quaternary history ofthe Marmara Sea and Black Sea from high-resolution seis-mic and gravity-core studies. Mar. Geol. 190, S0025-3227(02)00350-X.

Hiscott, R.N., Aksu, A.E. Yas'ar, D., Kaminski, M.A., Mudie,P.J., Kostylev, V., MacDonald, J., Is'ler, F.I., Lord, A.R.,2002. Deltas south of the Bosphorus Strait record persistentBlack Sea out£ow to the Marmara Sea since V10 ka. Mar.Geol. 190, S0025-3227(02)00344-4.

Julian, M., Linienberg, D.A., Nicod, J., 1987. Ro“le des mod-i¢cations des niveaux quaternaires des mers Caspienne,Noire et Me¤diterrane¤e dans la formation du relief de leursmarges montagnardes. Me¤diterrane¤e 2^3, 19^35.

Kaplin, P.A., Shcherbakov, F.A., 1986. Reconstruction ofshelf environments during the late Quaternary. J. Coast.Res. Spec. Issue 1, 95^98.

Kraft, J.C., Chrzastowski, M.J., Belknap, D.F., Toscano,M.A., Flecher III, C.H., 1987. The transgressive barrier-la-goon coast of Delaware: morphostratigraphy, sedimentarysequences and response to relative sea level. In: Nummedal,D., Pilkey, O.H., Howard, J.D. (Eds.), Sea Level Fluctua-tion and Coastal Evolution. SEPM Special Publication 41,pp. 129^143.

Kukal, Z., 1971. Geology of Recent Sediments. AcademicPress, London, 490 pp.

Kvasos, D.D., 1983. Causes of the marked regression of theBlack and Caspian Seas about ¢ve million years ago. Ocean-ology 23, 331^335.

Latif, M.L., Oº zsoy, E., Salihogfllu, I., Gaines, A.F., Bas'tu«rk,Oº ., Y|lmaz, A., Tugflrul, S., 1992. Monitoring via direct mea-surements of the modes of mixing and transport of waste-water discharges into the Bosphorus under£ow. Middle EastTechnical University, Institute of Marine Sciences, TechnicalReport No. 92-2, 98 pp.

Mestel, R., 1997. Noah’s £ood. New Sci. 156, 24^27.McInnis, D., 1998. Two geologists trace Noah’s Flood to theviolent birth of the Black Sea. Earth August, 46^54.

Mihailescu, N., 1989. The Evolution of the Fluviatile Networkof the Danube Delta in Pleistocene and Holocene. Travauxdu Museum d’Histoire Naturelle ‘Grigore Antipa’ 30, pp.355^366.

Myers, K.J., Milton, N.J., 1996. Concepts and principles ofsequence stratigraphy. In: Emery, D., Myers, K.J. (Eds.),Sequence Stratigraphy. Blackwell Science, Oxford, pp. 11^44.

Ogfluz, T., Latun, V.S., Latif, M.A., Vladimirov, V.V., Sur,H.I., Markov, A.A., Oº zsoy, E., Kotovshchikov, B.B., Ere-meev, V.V., Uº nlu«ata, Uº ., 1993. Circulation in the surfaceand intermediate layers of the Black Sea. Deep-Sea Res. I40, 1597^1612.

Okay, A.I., S'engo«r, A.M.C., Go«ru«r, N., 1994. Kinematic his-tory of the opening of Black Sea and its e¡ect on the sur-rounding regions. Geology 22, 267^270.

Oktay, F.Y., Eren, R.H., Sak|nc', M., 1992. Sedimentary geol-ogy of eastern Thrace Oligocene Basin around Karaburun-Yeniko«y (Istanbul). In: Proceedings of the 9th PetroleumCongress and Exhibition of Turkey, Ankara. Associationof Turkish Petroleum Geologists, pp. 92^101.

Oktay, F.Y., Go«kas'an, E., Sak|nc', M., Yalt|rak, C., Imren, C.,Demirbagfl, E., 2002. The e¡ects of the North AnatolianFault Zone on the latest connection between Black Seaand Sea Marmara. Mar. Geol. 190, S0025-3227(01)00246-8.

Oº zsoy, E., Latif, M.A., Tugflrul, S., Uº nlu«ata, Uº ., 1995. Ex-changes with the Mediterranean, £uxes and boundarymixing processes in the Black Sea. In: Briand, F. (Ed.),Mediterranean Tributary Seas. Bulletin de l’Institut Oce¤an-ographique, Monaco, Special No. 15, CIESME Science Se-ries 1, pp. 1^25.

Oº zsoy, E., Latif, M.A., Sur, H.I., Goryachkin, Y., 1996. Areview of the exchange £ow regimes and mixing in the Bos-phorus Strait. In: Briand, F. (Ed.), Mediterranean TributarySeas. Bulletin de l’Institut Oce¤anographique, Monaco, Spe-cial No. 17, CIESME Science Series 2, pp. 187^204.

Pfannensteil, M., 1944. Diluviale Geologie des Mittelmeerge-bietes die Diluvialen Entwicklundgstadien und die Urge-schite von Dardanellen, Marmara Meer und Boshphorus.Geol. Rundsch. 34, 334^342.

Piper, D.J.W., Aksu, A.E., 1992. Architecture of stacked Qua-ternary deltas correlated with global oxygen isotopic curve.Geology 20, 415^418.

Pirazzoli, P.A., 1996. Sea-Level Changes: the Last 20 000Years. John Wiley, New York, 211 pp.

MARGO 3158 4-10-02


Polat, C'., Tugflrul, S., 1996. Chemical exchange between theMediterranean and Black Sea via the Turkish Straits. In:Briand, F. (Ed.), Dynamics of Mediterranean Straits andChannels. Bulletin de l’Institut Oce¤anographique, Monaco,Special No. 17, CIESME Science Series 2, pp. 167^186.

Prentice, I.C., Guiot, J., Harrison, S.P., 1992. Mediterraneanvegetation, lake-level and paleoclimate at the Last GlacialMaximum. Nature 360, 658^670.

Ryan, W.B.F., Pitman III, W.C., Major, C.O., Shimkus, K.,Maskalenko, V., Jones, G.A., Dimitrov, P., Go«ru«r, N.,Sak|nc', M., Yu«ce, H., 1997. An abrupt drowning of theBlack Sea shelf. Mar. Geol. 138, 119^126.

Ryan, W.B.F., Pitman III, W.C., 1999. Noah’s Flood: theNew Scienti¢c Discoveries about Events that Changed His-tory. Touchstone Book, Simion and Schuster, New York,319 pp.

Sak|nc', M., Yalt|rak, C., Oktay, F.Y., 1999. Paleogeographicalevolution of the Thrace Neogene Basin and the Tethys ^Para-Tethys relations at northwestern Turkey (Thrace). Pa-laeogeogr. Paleoclimatol. Paleoecol. 153, 17^40.

Serebryanny, L.R., 1982. Postglacial Black Sea coast £uctua-tions and their comparison with glacial history of the Cau-casian high mountain region, In: Kaplin, P.A. et al. (Eds.),Sea and Oceanic Level Fluctuations for 15 000 Years (inRussian). Nauka, Moscow, pp. 161^167.

Stuiver, M., Reimer, P.J., Bard, E., Beck, J.W., Burr, G.S.,Hughen, K.A., Kromer, B., McCormac, G., van der Plicht,J., Spurk, M., 1998a. INTCAL98 radiocarbon age calibra-tion, 24000-0 calBP. Radiocarbon 40, 1041^1083.

Stuiver, M., Reimer, P.J., Braziunas, T.F., 1998b. High-preci-sion radiocarbon age calibration for terrestrial and marinesamples. Radiocarbon 40, 1127^1151.

Ternek, Z., 1964. The Geological Map of Turkey, IstanbulMap Sheet (1:500 000). Institute of Mineral Research andExploration (MTA), Ankara.

Tokay, M., 1964. The Geological Map of Turkey, ZonguldakMap Sheet (1:500 000). Institute of Mineral Research andExploration (MTA), Ankara.

Turgut, S., Tu«rkaslan, M., Perinc'ek, D., 1991. Evolution ofthe Thrace sedimentary basin and its hydrocarbon prospec-tivity. In: Spencer, A.M. (Ed.), Generation, Accumulationand Production of Europe’s Hydrocarbons, Special Publica-tion of the European Association of Petroleum GeoscientistsNo. 1. Oxford University Press, Oxford, pp. 415^437.

Uchupi, E., Ross, D.A., 2000. Early Holocene marine £oodingof the Black Sea. Quat. Res. 54, 68^71.

UNESCO, 1969. Discharge of Selected Rivers of the World,Vol. 1: General and Regime Characteristics of Stations Se-lected. Studies and Reports in Hydrology, 70 pp.

UNESCO, 1993. Discharge of Selected Rivers of the World,Vol. 2: Monthly and Annual Discharges Recorded at Var-ious Selected Station. Studies and Reports in Hydrology,600 pp.

Winguth, C., Wong, H.K., Panin, N., Dinu, C., Georgescu, P.,Ungureanu, G., Krugliakov, V.V., Podshuveit, V., 2000.Upper Quaternary water level history and sedimentation inthe northwestern Black Sea. Mar. Geol. 167, 127^146.

Y|lmaz, Y., Tu«yzu«z, O., Yigflitbas', E., Genc', S'.C., S'engo«r,A.M.C., 1997. Geology and tectonics of the Pontides. In:Robinson, A.G. (Ed.), Regional and Petroleum Geology ofthe Black Sea and Surrounding Region. AAPG Memoir 68,pp. 183^226.

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