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4 GEOGRAPHY 1 generations differ inabsolute andrelative in thisstudy. ofdifferent age Surfaces distinguished floodplain anddeltasurfaces correlate withfour generationsofancient floodplaintopography, that Novocaspian agesinthemodern - oftheLateandalternations Khvalinian of three transgressive-regressive phase Volga valley. There are pronounced traces of alluvialenvironments intheLower phases associated withthedominance transgressions alternated withregressive and Novocaspian transgressions. The correspondent to theLate Khvalinian phases withinthe Volga-Akhtuba valley there have (estuarine) beensixmarine level oscillations. Onlyover thelast16ka, oftheCaspianSeaa complexhistory The associated successionreflects the entire Late Pleistocene andHolocene. wereAstrakhan, changing throughout the present-day citiesof and intheareaingressional between estuary andalluvialenvironmentsmarine inthe alongstream. 700 km The estuarine- the apexof Volga haswandered Delta lowstandat–100m,Holocene Mangyshlak highstandof+50mandtheEarlyKhvalinian Caspian Sealevel theEarly rise. Between location controlled bytheamplitude ofthe withtheapexdeep ingressional estuary transformedperiodically into alongand lower parts Its the last600–700ka. during within thepresent-day Lower The palaeo-Volga valleyexisted River 2 Georgy I.Rychagov Corresponding author * Tel. [email protected] +74992450310,fax+72480162,e-mail: Tel. [email protected] +74959395469,fax9395044,e-mail: 119991, , ABSTRACT OF LOWER VOLGA DELTAS HISTORY OF FORMATION PALAEODELTAS Moscow State Pedagogical University, M.Pirogovskaya, 119991,Moscow, Russia Faculty ofGeography, Moscow State University, Gory, Leninskie 1 , Vladislav N.Korotaev types. generations oflocalfloodplainsurface subdividedinto differentcan befurther branch;main channelandtheAkhtuba they ii) are:types i)ancient(central) floodplainand age. distinguishedsurface These clearly differ and inheight,location,morphology withinthevalleybottom that types surface theformationdetermined main of two channel system oftheLower Volga River Long existence of acomplexmulti-thread landforms.characteristic and Baer’s widespread moundsare very Late plainareas, Khvalinian aeolianlandforms offlat-bottomednetwork hollows. Within the withdendritic a monotonous even surface accumulationplainhave marine Khvalinian areas of the Early The adjacentinterfluvial box-like cross-sectionshape.a symmetric floodplain, lackofprominent and terraces wide byawell-developed characterized is largely It occupiedbyreservoirs. parts differentis geomorphically from itsupstream valley (downstream from the Volgograd city) The ofthe Volga-Akhtuba part Volga River delta palaeodelta, ancientfloodplain,bay-head topography, andpresent-day vegetation. heights, offloodplain morphological types INTRODUCTION KEYWORDS: 1 *, Aleksey V. Chernov modern floodplainsoftheVolga River Volga-Akhtuba valley, 2 50.0016:19:13 16:19:13 05.08.2010 ggi209.indd 5 i 2 0 9 . i n d d

Bolshoy Volgograd bendofthe fault. Asharp with thatofthe Volgograd flexure andthe coincides direction southwestern strike the fracturezone.Volzhsko-Ergeninskiy Its and the Kamyshin Volgograd citiesfollows the Quaternary. between The valleysection developed atleastsincethebeginning of negative inherited River tectonic structures valleyoftheLowerThe modern Volga and eroded ontop. strongly deformed onlimbsofsaltdomes rock whichisPleistocene sedimentary level consistsoftheUpperPermian and open onthesurface. The oversalt structural orElton, somestocks aresuch asInder Neogenic rocks. thebrockensaltdomes, In they are byMesozoic overlain oreven stocks insuchdomesreaches 6to 8km; Zaymichenskiy, etc. The heightofsalt or gigantic domes–Enotaevskiy, Soleno- salt bodiesthatform extensivesaltridges Lower Volga region haslarge underground exceeding 4km. strata hadathickness The (Lower Permian) whichinitial evaporites stage massesoftheKungurian enormous formed asaresult ofplasticdislocations mantle. depression sedimentary They were elements ofthePricaspian tectonic Salt domesare themainstructural dislocations.by fracture relatively large platform structuresbroken rocks oftheLate Palaeozoic thatform composed oftheterrigenous-carbonate levels. level isThe undersaltstructural structural undersalt, oversalt, andsuperficial the Russianplatform mantlethatconsistsof rocks of and are bysedimentary overlain Archaean-Proterozoic type metamorphic of thedepression mainlybelongto the basement rocks thatcomposecrystalline separated blocksatdifferent elevations. The isfracturedinto It depths exceeding 15km. basement ofthedepression isfound at geophysical data,pre-Palaeozoic crystalline According to part. anticline initsfarsouthern with afolding structureoftheKarpinskiy and deepestwithintheRussianplatform Pricaspian tectonic depression –thelargest The Lower Volga region islocated withinthe 5 heterogeneous layer of Quaternary deposits heterogeneous layer ofQuaternary mantleistopped witha The sedimentary and microfossil communities. byspecificmacro- characterized distinctively andApsheronianAkchagylian depositsare sand or, withbasalclays. marls lessoften, The sediments (clays andsilts)withlayers of deposits are dominated byrelatively fine and Apsheronian transgressions. These theAkchagylian sedimentsduring as marine ofthesedepositswere Most formed thick. depositsfew hundred meters Quaternary of unconsolidated UpperPliocene – mantleismainlycomposed sedimentary of thePaleozoic-CenozoicThe upperpart wide(Fig.12–15 km 1). with localrelatively narrower upto sections downstream itincreases tofarther 30–35km Volgograd whereas does notexceed 3–8km, For example, thevalleywidthupstream of basement. Pricaspian depression crystalline by tectonic anddislocationsofthe structures arechannel morphology largely controlled formation, structure, geomorphic and 1962]. Thus, theLower Volga valley River [Lower Volga River..., 2002;Nikolaev, andmorphometry channel morphology ofthe in localcharacteristics Volga River reflectedsections. Suchinfluenceisoften direction andformation ofnarrowed valley valleyfromRiver itsgeneralsouthern cause localdeviationsoftheLower Volga structures These andothersimilaractive etc. branchinlet,Kamennoyarskiy, Akhtuba Volgograd atthe city, Verkhne-Akhtubinskiy the nearby such assaltdomesBeketovskiy structures withhalokinesis superimposed until theHolocene. Tectonic depressions are deep fracturezone whichremained active Both ofthesestructures coincidewith the depression. southward –theNizhne-Volzhskiy (down to theCherniy Yar settlement),farther depression itfollows theArzgirskiy part, linear depression thenorthern structures. In valleyisformedRiver large alongthetwo The oftheLowerVolga-Akhtuba part Volga direction. strike fault ofthesoutheastern 90° –isassociated withtheAkhtubinskiy the valley nearby Volgograd –to almost city 005.08.2010 16:19:13 5 . 0 8 . 2 0 1 0

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6 GEOGRAPHY

6 1 and Holocene)canbedistinguished system (Lower, UpperPleistocene, Middle, layer, allmajorsubdivisionsoftheQuaternary exceeding 100minthickness. Within this formation witha iscloselyconnected ofthe The history Volga palaeodeltas River directions. both lateral andvertical numerous different faciesthatalternate in lakes limans, kultuks (lagoons (deltaic),lacustrine-marine marine presence ofcomplexorigin sediments:fluvial- thewidespreadSuch conditionsdetermine zoneinteraction andthe Volga mouth. River of continuousmigration ofthesea-land time, thestudyarea hasbeen aterritory present. For ofgeological alongperiod are alsodeposits andsomeothertypes aquatic environments, thoughalluvialfan most widespread withinsedimentsofnon- lagoon deposits. Aeolian deposits are the aquatic sediments, i.e., fluvial, lacustrine, represented byheterogeneous non-marine is ofthegeological section Significant part andNovocaspianKhvalinian, transgressions. Lower Lower andUpperKhazarian, andUpper sedimentsformed theBaku, marine during depositsare dominated by Quaternary scale. stratigraphicrespond Pleistocene to oftheInternational Middle sions. Lower Pleistocene oftheRussianscalecor- andMiddle In thispaper, In authorsusetheRussianstratigraphic subdivi- , ilmens ). Such deposits often consistof ). Suchdepositsoften ), and fluvial-lacustrine (oxbow), andfluvial-lacustrine Figure.the Volga-Akhtuba1. Width Variabilityof Valley. 1 , . ( Caspian SeaatleastsincetheLate Neogene Volga hasbeendraininginto River the with ahighdegree ofconfidencethatthe et. al., 2000,2004]allowed usto conclude data [Goretsky, 1966;Rychagov, 1977;Svitoch present time. Reviewofpreviously published remained prominenthave upto partly the mouth andspecificlandform complexes that This system hadacontinuouslymigrating Volga region theentire during Late Cenozoic. to thepresent-day valleyexisted intheLower suggests thatalarge riversystem comparable development ofthe Volga valley River The aforementioned ofthe history oscillation, andtectonic activity. flowvariations,by river theCaspianSealevel controlled processlong-term wasprimarily floodplain formation. This complexand valley, and, inparticular, the Volga-Akhtuba oftheLowergeneral history Volga River suggests thatinthepast, palaeo-Volga valleys.than thewidthsofmodern This fact widths are usuallyfour to five timeslarger resemble valleys. themodern However, their Planforms ofthesepalaeovalleysgenerally the eastfrom themodern Volga valley. The ( Krivichi Venedy ( N ap ). The buried Volga palaeovalleys ofthe Q Q kr vd ) ageshave beendiscovered to ), Solikamsk ( ), Solikamsk Q sk ) and Early ) andEarly 005.08.2010 16:19:13 5 . 0 8 . 2 0 1 0

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dated to the( bodies located atdepthsof40–25mand represented depositional bywedge-shaped [1990]. E.G. Maev These paleodeltasare geological byM.Yu. structure Lohin and were discovered intheCaspianSea shelf regressions. Traces ofsuchpalaeodeltas ofpalaeodeltasdueto sea preservation Late Pleistocene andHoloceneisapoor Volga the mouthdynamicsduring River featuresOne ofcharacteristic ofthe following thesealevel oscillations. and downstream thepalaeo-Volga valleys into migration accounttheiractive up- takes task becomeseven more difficultwhenone ofpalaeodeltalocations.determination The adetailed doesnotpermit sections, of oldalluvialsuccessionsingeological stated above, arelatively poorpreservation compared to thepresent. As itwasalready dischargesRiver were significantly greater infilled withthegravels, pebbles, sandsand from themodern Volga valley. River ispartially It Cretaceous-Palaeogene bedrock to theeast palaeovalley incised300–500minto the programcoring discovered alarge buried are Pliocene. dated to the Middle Deep Pricaspianvalley found region intheNorth First geological tracesofthepalaeo-Volga of themodern . River transgression, to almosttheseaward edge maximum stageoftheLate Khvalinian settlement correlated with the Nikolskoe valley from thecoastlineremnants near both sidesofthemodern Volga-Akhtuba The Baer’s moundslandscapeistracedon of theBaer’s moundslandscapeformation. landforms thatform –sandyridges thebasis formation oftheabovementioned specific with theLate Seaexistence Khvalinian – event geomorphic correlated important far. This may betheconsequenceofan regression, have notbeendiscovered so those thatcorrelated withtheMangyshlak ages. Palaeodeltas oflater ages, for example RIVER PALAEODELTAS PLEISTOCENE HISTORY OF THE VOLGA 7 Q at ) andEnotaevsk( Q en ) been submerged andhadlandscapes The palaeo-Volga mouthmay have located upstream city. from theAstrakhan Venedy andCherniy Yar valleydeltaswere Atel age sands. Thus, itispossiblethatthe are noancientalluvialdepositsolderthan ofthemodern section Volga deltathere On theotherhand, withinthegeological these riversystems have beenfound there. almost notracesofdeltascorresponding to thePleistocene.valley during However, the existence ofthelarge palaeo-Volga River channelalluvialfacies,the active proving The depositsare dominated of bymaterial rivicola, Sph.corneum, Planorbis planorbisetc. pictorum, Pisidium amnicum,Sphaerium duboisianus, V.viviparus, Uniotumidus, U. polymorpha, Valvata piscinalis, Viviparus Lithoglyphus caspicus, L.naticoides, Dreissena contain shellsofthefreshwater mollusks offreshwaterby avariety sediments that age deposits. These depositsare represented succession oftheCherniy Yar sandsandAtel Singil, Lower successions, and Krivichi abovementioned depositsofthe Venedy, [Goretsky, 1966]allowed to distinguish the ofthemodern sections Volga valley River [3]andgeologicalthe Hydroproject Institute Volga outby region. carried coring Deep in thePleistocene depositsoftheLower palaeo-Volga valleyincisionshasbeenfound Numerous evidenceofexistence ofafew Basin. Balakhany and flowed into aclosedwater body–the deltawithintheCaspiandepression modern delta waslocated farto thesouthfrom the agepalaeo-Volga (Kinel) that theAkchagylian hasbeensuggested now studiedindetails. It A.N. Mazarovich in1936andhave beenby were by firstdistinguishedanddescribed succession, deposits identifiedastheKinel ofthisregionnetwork andassociated Middle Volga region. The ancientdrainage deposits found valleysofthe insimilarburied succession succession depositswiththeKinel south. Allresearchers correlate theKushum andfarther Lake upland to theBaskunchak traced from western slopesoftheObshiySyrt successionandis clays oftheKushumskaya 005.08.2010 16:19:16 5

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8 GEOGRAPHY

8 a large river channel during the middle-end a large themiddle-end riverchannelduring suggest thatthesedepositswere formed in fauna remnants, andlithological properties Cherniy Yar successionsands, characteristic The stratigraphic positionandaltitudeofthe Pleistocene. oftheMiddle the middlepart to ageisusuallyattributed palaeofauna. Its remnants oflarge mammalsoftheKhazarian channel sands, containingnumerous bone is mainlyrepresented cross-stratified byactive LithologicallyZaimishe geological it section. intheCherniy described Yar –Nizhnee of theCherniy Yar successionhasbeen orSingil deposits. Khazarian The stratotype the erosional oftheLower unconformity Yar successionare widespread. They overlie polyfacial alluvialdepositsoftheCherniy settlement, andNikolskoe the Raigorod the In Volga between valleysection River Caspian. the North marginCaspian Seawasatthesouthern of regression ofthe the deeppre-Khazarian agedeltaduring the locationofKrivichi day Ergeni upland. However, mostlikely modern Volga valley, River nearthe present- that timewaslocated to thewest from the [1966],thepalaeodeltaof by G.I.Goretskiy in theLower Volga region. As suggested agedrainagenetwork oftheKrivichi pattern is noreliable information onthespatial thatperiod. of theCaspianSeaduring There deposits, proving adeepeningregression age alluvialsandsoverlay theSingil age flowing water bodies. Krivichi The Early tranquil waters ofvaststagnant orsemi- under conditionsofslowsedimentationin the formation ofthesedepositsoccurred polymorpha etc. Planorbis planorbis, Theodoxus sp., Dreissena amnicum, Sphaeriumrivicola, Valvata piscinalis, cf. pictorum,Viviparusduboisianus, Pisidium patens Salvinia ( contain abundantremnants ofvegetation valley and Western Pricaspian region. They widespread withintheLower Volga River ages. Khazarian) The Singil agedepositsare (pre-Early Singil Krivichi (past-) andEarly Dnieper-Bug the andDunay limanesduring morphologically similarto themodern Selaginella selaginoides, Azolla interglacialica, selaginoides, Azolla Selaginella ) andfreshwater mollusks(Unio ). These datasuggestthat mainly from suspendedsediment delivered deposited initsrelatively stagnant waters, plicatus)were caspia,Hypanis (Monodacna fauna type molluscs oftheslightlybrackish The so-called “chocolate” clays withrare exceeded 40m.The depthoftheestuary with relatively coldslightlysalinewaters. wasfilled It Luka. as to theSamarskaya approximately asfarupstream 500km, stretched toby anarrow and longestuary Volga wasrepresented valleyofthatperiod city.Kamyshin The submerged palaeo- fromPricaspian the lowlandto thenorth ofthethe seacovered theentire territory transgression Khvalinian Early maximum, CaspianSea.Later,Southern the during and theNorthern between boundary of thesameagediscovered alongthe Volga valleyisproven bydeltadeposits The existence oftheAtel agepalaeo- at thattime. flowing water bodieswithinpalaeovalleys which proves thepresence ofclearwarm Theodoxus sp., polymorpha,etc. Dreissena Bithynia tentaculata,Planorbis planorbis, Valvata piscinalis, Lithoglyphuscf. naticoides, shells ( findings, includingfreshwater mollusk bydiversecharacterized palaeontological respectively). These depositsare andUrundzhik, Sea (theLate Khazarian “warm” transgressions oftheCaspian correlated withrelatively low-amplitude deposits ofthepalaeo-Volga are River and Singil successionalluvialanddeltaic Didacna surachanica). The Cherniy Yar Sealevel (depositswithLate Khazarian into deltaic depositscorrelated withthe Cherniy Yar successionchangelaterally settlement, where alluvialsandsofthe neartheSeroglazovkageological section byanalysisofthestatement issupported Pleistocene.region theMiddle during This deltaexistedRiver intheLower Volga Another generationofthepalaeo-Volga higher. of themodern Volga River, orwasslightly mean low-water level coincidedwiththat Pleistocene.of theMiddle The palaeoriver Unio pictorum,Viviparusduboisianus, 005.08.2010 16:19:17 5 . 0 8 . ), 2 0 1 0

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and Davan depressions thatformed atthe valley.only itspre-Khvalinian The Sarpinskaya sea, thepalaeo-Volga not inherited River 14–16 mand4–6m.Following theretreating ataltitudesof20–22m, the stadialterraces thatresultedfluctuations intheformation of by high-amplitudesea-levelmarked Searegression Khvalinian The Early was to thenorth. bedload sedimentwasdeposited farther representedmaterial bythepalaeo-Volga by theriver. isbelieved thatthecoarser It 9 Volga 2–Marineaccumulative Delta.1–Highlandaccumulative-denudation, planeofEarlyKhvalinian, Akhtuba Valley. A– MaximumstageoftheLate Khvalinian transgression (0mBSL),B–Maximumstage Novocaspian (9–5ka,–9–(–18)mBSL),7–Floo of theMangyshlak regression (-100mBSL(i.e, BalticSystem Level). C–Recent stageofformation the BSL), 8–Recent Volga Deltaandmarine islands(less1ka,–25–(–27)mBSL),9– Volga Channelofthe 5 –Floodplane ofLate Khvalinian (17–12 ka,–3–(–9)mBSL),6–Floodplane Turali of 3 –Marineaccumulative planeofLate Khvalinian, 4–Marineaccumulative planeofNovocaspian, Figure 2. oftheLowerThe history Volga palaeodeltasformation andtheirpositioninthe Volga- Late Khvalinian, 10 –water 11–river surface, systems, river 12–relict systems, 13–isobaths. dplane Ulluchay ofNovocaspian (4–1,5ka,–18–(–23)m Sea bottom. Erosional ofthe dissection fromin cores thepresent-day taken Caspian ofthe boundary “chocolate” clays observed evident from anduneven thesharp upper by theCaspianSea. oferosionThe period is the southwhichare, atpresent, occupied Pricaspian lowlandandinthelandareas to tookerosion. placebothwithinthe Incision depositswereKhvalinian to intensive subject theEnotaevskregression,During theLower topography. same timeare stillprominent inthemodern 005.08.2010 16:19:17 5 . 0 8 . 2 0 1 0

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10 GEOGRAPHY

1 0 Sarpinskaya depression wasonceagainfilled Sarpinskaya the LateSeatransgression. Khvalinian The substantial relief transformations during plainexperienced marine Khvalinian The Early 1977; Varushchenko et.Al., 1987]. [Kroonenberg et.Al., 1997,2008;Rychagov, the riversflowinginto theLateSea Khvalinian the zones of ofpalaeodeltasandestuaries Moreover, theyare mostlyassociated with to the Latetransgression.subject Khvalinian that was are located withintheterritory isundisputable:allsuchlandformsfact distinguished bydifferent authors, one in theBaer’s areas moundsdistribution topography. discrepancies Despitecertain for Baer’s themodern moundslandscape landforms (i.e., formed sandyridges) abasis estuaries. We suggestthat thesedepositional marginal seas, andinriverdeltas with significant tidalamplitude, inshallow bay andgulfoutlets, alongopencoastlines commonlydevelopSuch sandyridges at of erosion deposits. oftheoldermarine of sedimentdelivered asaresult byrivers of suchlandforms wasasubstantialamount for thedevelopment condition necessary shelves ofmany present-day seas. Another were widespread similarto sandridges on of theLateSea. Khvalinian These landforms landforms inthecoastalzone underwater favoured theformation ofaccumulative directed hydraulic andsurge currents coastal zone. ofoppositelyThe interaction specific hydrodynamic conditionsinthe planform oftheseacoastlinedetermined and day Kamyshin Volgograd cities. Sucha waslocated thepresent- between part valley, theLate Seabay Khvalinian apical Uil, Sagiz, the andEmbarivers. In Volga River Uzen, the mouthsofBolshoyandMaliy flowed into theestuary. Bays alsoexisted in depression mouth (Fig. 2-A). The UralRiver SeaattheSarpa-Davan the palaeo-Caspian maximum, there wasafunnel-shapedbay in theLate transgression Khvalinian During Sea. coastline configurationoftheLate Khvalinian regression thecomplicated determined theEnotaevsk plainduring Khvalyn Early [Goretsky, 1966]. Within ancientdeltas a crest-like ageclays fold oftheMaikop specifically, theanticlinerepresented by the bifurcation ofthe Volga channel, River The tectonic hasalsodetermined structure tectonic control over thevalley’s direction. anticline)isanexampleof Akhtubinskaya the Volgogradskiy faultandthe Verkhne- with valley(closelyconnected Akhtuba The geological ofthe structure Volga- branch.later developed into theAkhtuba faultstructure, followed theAkhtubinskiy main channel, branchthat whiletheleft branch gave to themodern rise Volga River delta. The larger right andmostactive infill(Volgograd) the Lateestuary Khvalinian mainbranchesof two inherited most likely branch)havemain channelandAkhtuba quasi-independent watercourses (the Volga oftime.also took placeatthatperiod Two Volga channeldichotomy River formation of thevalley. isprobable thattheLower It sideand insomeotherlocationsontheleft settlement,near theLeninsk city, Sokrutovka side ofthe right Volga-Akhtuba, aswell as settlementson the andStaritsa Vyazovka nearthe its fragments canbeobserved is notprominent topography, inthemodern valley(Fig.River 2-B).Althoughthisterrace that currently existsinthemodern Volga terrace, (Sarpa of thefirstterrace 14–17ka) regression corresponds to theformation The beginning oftheLateSea Khvalinian –30–(–32) m(Samurphase). phase), –16–(–18)m(Dagestanand (Kuma phase),–11–(–12)m(Sartassk can betracedonaltitudesof–5–(–6)m in formation ofcoastlineswhichremnants transgressive phases. These events resulted retreat wasinterrupted byrelatively limited period, theLate Sea Khvalinian Khvalinian relief.in themodern to theEarly Similarly incised deltas. The latter are stillprominent valleywere byasystem dissected of Akhtuba areas to theeastfrom thepresent-day Volga- depressionVolga and valleyandSarpinskaya flow.with ariver the between The interfluves OF THE VOLGA-AKHTUBA VALLEY HOLOCENE BAY-HEAD PALAEODELTAS 005.08.2010 16:19:23 5 . 0 8 . 2 0 1 0

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main channel and the Akhtuba branch; main channelandtheAkhtuba floodplainsofthe i)themodern Volgaof: not uniform. As discussedabove, itconsists ofthe structure Volga-Akhtuba floodplainis geomorphologicaltransgression. The and HolocenesincetheLate Khvalinian theLatewhich took Pleistocene placeduring infillbythe estuary Volga sediment, River of theAstrakhan-Volgograd ingressional data allowed usto thelaststages reconstruct images, andtopographic andgeological andsatelliteAn analysisofavailable aerial branch. Akhtuba both the Volga mainchannelandthe River of was formed activity bygeomorphic channel.River The Volga-Akhtuba floodplain anastomosing oftheLower pattern Volga and eventually gave to themodern rise infillof theAstrakhan-Volgograd estuary relatively continuousalong many stages and more separated. This process remained retreating sea,thebranchesbecamemore migrated downstream following the channels. However, asdeltasgradually interconnected bynumerous secondary mainbranchesremainedtwo closely andyounger), these(Akhtubinskaya 1 1 Figure 3. The diagram ofchangesintheCaspian Sea-level duringLate Pleistocene –Holocene andthe main periodofformation ofthe Volga-Akhtuba G.I.Ruchagov, floodplain[after 1977] alluvial environments placeinthe hastaken and oftheestuarine-marine Alternation Lower Volga River..., 2002;Nikolaev, 1962]. and Chernov, 2000,2001;LiC.X.et.al., 2004; of the Volga 1951;Korotaev, Delta, River systems ofRussiaandChina..., 2007;Geology 1990;Estuarine-deltaic [Bolikhovskaya, ofancientfloodplaingenerations surfaces are commonlyabout1mhigher than floodplain leveesoverlain ofthemodern water level. However, itmustbenoted that similar relative elevationsover themeanlow- have andancientfloodplain surfaces modern andmorphology.by theirstructure Both area. These elementscanbedistinguished 80% oftheentire Volga-Akhtuba floodplain branchoccupymore than and theAkhtuba located the between Volga mainchannel Different generationsoftheancientfloodplain topography. channel)primary (the Akhtuba Volga mainchannel)orsegmented-ridge bydepression-islandis characterized (the along the Volga channels. It andAkhtuba (Fig. floodplainisstretched 2-C). The modern consecutively downstream alternating offourby sections different generations and ii)theancientfloodplainrepresented 005.08.2010 16:19:24 5 . 0 8 . 2 0 1 0

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12 GEOGRAPHY

1 2 floodplain andthebifurcation ofthemain ofthe section Zamyanskiy Volga-Akhtuba City.the The formation ofthe of the Volga deltadownstream River from regression incisionsatthepresent location the Baer’s mounds andtheMangyshlak deposits filledthedepressions between same time, the Novocaspian transgression of theNovocaspian transgression. Atthe the during City the Astrakhan Turali stage from thepresent-day locationofnorth existed inthe Volga valleyto River the Turali stage).Arelatively bay smallmarine themaximumphase(theBSL during reachedtransgression –20m andfurther the firstphaseoftheNovocaspianduring Caspian Sealevel grew to –25mBSL the Baer’s moundsbywave action. The regression andsimultaneouserosion of incisions formed theMangyshlak during depositional infillofdeep Volga River transgression wasaccompaniedwiththe The beginning oftheNovocaspian branches. discharge was passingthrough thesetwo The entire post-Khvalinian time, Volga River location ofthepresent-day Volga delta. River deposits forming mainchannelsatthe two eroded transgression theKhvalinian partly the Volga channelinciseddeeplyand River CaspianSea.As ofthemodern aresult, parts andcentral thenorthern between boundary The Volga deltawasthenlocated River atthe the sealevel retreated to about–100mBSL. followed regression bytheMangyshlak when transgressionThe Late Khvalinian was Lowervalley. Volga dominance ofalluvialenvironments inthe regressive phasesassociated withthe ages (Fig. 3). These events alternated with andNovocaspianof theLate Khvalinian valley correspondent to transgressive phases phaseswithinthe (estuarine) Volga-Akhtuba there wereover thelast16ka, sixmarine of theCaspianSealevel oscillations. Only This successionreflected acomplexhistory the entire Late Pleistocene andHolocene. day Volgograd citiesduring andAstrakhan thepresent- between ingressional estuary continuing development of the estuary continuing development oftheestuary transgression bythe wascharacterized Thus, thesecondstageofNovocaspian the deltaicplaininto large lowlandislands. existingincisionsandseparatedinherited oftime. thatperiod during part They have already existed inthedeltaupper – andAkhtuba and Buzan,Bushma,Kigach, valley–the Akhtuba Volga mainchannel, main branchesofthepresent-day Volga- incision ofthedeltaicwatercourses. The amplitude anddidnotcausesignificant Novocaspian transgression waslimited in regression peaksofthe separatingthetwo can thereforeIt beconcluded thatthe ofthedelta. theseparts between observed areof sedimentationdiscontinuity deposits. However, noprominent traces by shallowseawaters upto 15mdeep) ofadeltasubmerged avandelta (distalpart are substantiallydifferent from thoseofthe ofthe characteristics conditions. Lithological stable sedimentary stagnant water bodieswithcalmand mainly infresh (orlessfrequently brackish) indicate thatsedimentationoccurred Valvata piscinalis, polymorpha Dreissena remnants ( numerous findingsoffreshwater mollusks sedimentcompositionandfine silt-clay modern Volga delta.Predominantly River are widespread over theentire area ofthe facies took place. Currently, thesedeposits sediment andfluvial-lacustrine) marine deposition ofthe rose upto –23–(–24)mBSLandActive BP)whentheCaspianSealevel (3,0–2,5 ka phase oftheNovocaspian transgression evolution wasassociated withtheUlluchay deltaformationRiver anditsgeomorphic The secondstageofthemodern Volga regression. incisions formed theMangyshlak during branchreturned into the and theAkhtuba that period, boththe Volga mainchannel but limited inamplituderegression. During was followed byarelatively prolonged stage oftheNovocaspian transgression branch took placeatthattime. The Turali channel atthepresent outletoftheBuzan Planorbis planorbis, Uniotumidus, kultuk-ilmen kultuk-ilmen (lacustrine- deposits 005.08.2010 16:19:26 5 . 0 8 . 2 ) 0 1 0

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Caspian Sealevel rise. location controlled bytheamplitudeof withtheapex deep ingressional estuary transformingperiodically into alongand were lower parts Its the last600–700ka. the present-day Lower Volga region during palaeo-Volga valleyexisted River within There issufficientevidencethatthe ofthedelta. distal parts sedimentation regimes are limited to only andavandelta andfluvial-lacustrine) marine of thedelta,while sedimentation regime nowprevails over most transformations. As aresult, thealluvial-deltaic played adominantrole inthedeltamorphology were controlled byhydrological regime which (floodplain, channel, naturallevees, etc.). They channel-floodplain landform complexes offluvialprocessescontribution thatformed bygreater development thathasbeenmarked oftheregional geomorphological history evolution generallycoincides withthe stageofthe The modern Volga delta River level hasnever above risen –25mBS. regression theDerbent After theCaspianSea banklocation). branch andtheBelinskiy Zelenginskiy Bay (attheancient Bushma ancient Buzanbranchlocation)andthe Bay (atthe astheSineeMortso century deltatopographyRiver 20th untiltheearly regression remained prominent inthe Volga incisions formed theMangyshlak during occupyingthemain large palaeo-branches of itsbranches. tracesoftwo Nevertheless, changes ofthedeltaplanform andpatterns causedanumberof sea level fluctuations mounds development. Later on,insignificant delta formation beyond thearea ofBaer’s specifically, theonsetofadvancing new stageofthe Volga deltaevolution, River level fell to –32mBSL. This event triggered a regressionthe Derbent whentheCaspianSea Novocaspian transgression wasfollowed by The Ulluchay stageofthemultiphase of advancingdelta. infilling deltaandtheonsetofformation CONCLUSION 1 3 kultuk-ilmen (lacustrine- Research (Grantno. 07-05-00525). the RussianFoundation for Fundamental byThis research wassupported work past CaspianSearegressions. the during multiplereworking underwent by theHolocenealluvialsedimentwhich floodplain. These remnants are overlain ofthemodern sections Volga-Akhtuba low-water level, ingeological are preserved under thepresent-day Volga mean River successions lyingdeeperthan20–25m why onlyremnants oftheoldest alluvial a substantialchannelincision. That is base level drop cannot be followed by incisions. Undersuchconditions, the did notfavor thedevelopment ofdeeper lowseawardwith extremely gradients shallowcoastalzone20–25 m.Avery Caspian Searegressions didnotexceed palaeo-Volga the channelincisionduring floodplain formation. The depthof the channel andfloodplainfaciesduring usuallyseparatedmaterial into active later andredeposited reworked asalluvial and lagoonsediment. This sedimentwas into previously deposited layers ofmarine Volga followed thefallingsealevel, incising theregressiveDuring phases, thepalaeo- fauna.sediment becamesettledbymarine conditions. such limane-like This finer bottom underoccurred ontheestuary gradual andcontinuoussedimentation waters, flowingslowlyseaward. Relatively sea level becamefilledwithslightlysaline ofthevalleylocated belowthearisenparts thetransgressiveDuring phases, thelower vegetation. offloodplaintopography,type andmodern absolute and relative heights, morphological in ofdifferent agegenerationsvary surfaces identifiedinthisstudy. types surface The generations ofancientfloodplainanddelta topography thatcorrelate withthree in themodern Volga-Akhtuba floodplain andNovocaspianLate Khvalinian ages transgressive-regressive phasesofthe There are pronounced tracesoffour ACKNOWLEDGEMENTS  005.08.2010 16:19:26 5 . 0 8 . 2 0 1 0

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1 4 . Korotaev, V.N., andChernov, A.V. anddynamicsofthe (2000).Morphology Volga-Akhtuba 6. Goretsky, G.I.(1966). The Volga River Valley formation inLower Pleistocene. andMiddle 5. Geologyofregion Volga Canal. –Don (1960).Edited by V.D. Galaktionov. Moscow– 4. Geologyofthe Volga (1951).Edited byM.V. Delta. River Klenova. The GOINProceedings, 3. systems ofRussiaandChina:hydrological-morphological procceses, Estuarine-deltaic 2. N.S.(1990).Palaeoindication oftheLower Bolikhovskaya, Volga Region landscape 1. 13. Nikolaev, V.A. (1962).Geological evolution, relief andalluvialdeposits. In: 12. Lower Volga geomorphology, River: palaeogeography andchannelmorphodynamics. M.Yu.,Lokhin, 11. andMaev, E.G.(1990). Pleistocene agepalaeodeltasonshelfof The Middle Li C.X.,Ivanov V.V.,10. Korotaev V., Yang S.Y., ofthe ChalovR.,andLiuS.G.(2004).Development N.S.,Lychagin Kroonenberg S.B., Kasimov M.Yu. (2008). The CaspianSea,anatural 9. Kroonenberg G.V., S.B., Rusakov Svitoch A.A.(1997). ofthe The wandering Volga delta:a 8. Korotaev, V.N., andChernov, A.V. (2001).Formation ofthe Volga-Akhtuba valleyfloodplain 7. 14. Rychagov, G.I.(1977). The CaspianSea Pleist REFERENCES floodplain. Publ.,Moscow, Nauka 412p. (in Russian). Leningrad, State Power SupplySources. Publ., 416p. (inRussian). vol. 18(30).Leningrad, Gidrometeoizdat Publ., 395p. (inRussian). Russian). andpredicationgeomorphology ofevolution. (2007).Moscow, GEOSPubl., 445p. (in geomorphology. evolution over thelast10thousandyears. In: (2002). Ed. by G.I. Rychagov and (2002). Ed. byG.I.Rychagov V.N. Korotaev. Moscow, `GEOSPubl., 241p. (inRussian). pp. 34–39(inRussian). part. Caspian Seanorthern the Middle Research Volga inResponseto Delta CaspianSea-Level Fluctuation Last100 during Year. for sea-level change.laboratory response to rapidCaspianSea-level change. (in Russian). and river channelprocesses and the Volga thelate Pleistocene palaeodeltasduring River andHolocene. In: University Publ.,University 268p. (inRussian). Publ.,University pp. 11–56(inRussian). agriculture oftheVolga-Akhtuba Valley andtheVolga Delta River , 20(1),pp. 152–165. Geomorfologiya Moscow, Nauka Publ.,Moscow, Nauka pp. 52–68(inRussian). , vol. 13.Moscow, State Publ., University Moscow pp. 229–240 , 3,pp. 61–69(inRussian). J. Geography Environment sustainability Vestnik Moscow StateUniversity, Geography J. Sedimentary Geology J. Sedimentary The -Questions ofgeologyand The Caspian Sea-Questions ocene history. Moscow, State Moscow . Moscow, State Moscow , 107,pp. 189–209. , No01.pp. 22–37. Nature and J. ofCoastal Soil erosion Soil , vol. 3, 005.08.2010 16:19:26 5 . 0 8 . 2 0 1 0

1 6 : 1 9 : 2 6 i0.nd15 15 gi209.indd works, including21monographs, 3thematicmapsand2atlases. ofregulationprinciples ofrivermouths. 150scientific Hehaspublishednearly 7 Varushchenko, S.I., Varushchenko, (1987) R.K. A.I.,and Klige, 17. Svitoch, A.A.,and Yanina, T.A. (1994).Structureanddevelopment ofthe Volga Delta. River 16. 15. Svitoch, A.A., and Badukova E.N. (2004). Buried vallesofLower E.N.(2004).Buried Svitoch, A.A.,andBadukova Volga. 15. works, including11monographs andtutorials. and11textbooks withtheBasicsofGeology”.“Geomorphology 150scientific Hehaspublishednearly Publ., 239p. (inRussian). and enclosedwater bodieshydrological regime thepalaeo-times. during , 4,pp.Geomorfologiya 11–24(inRussian). pp. 55–68(inRussian). works, including3thematicmapsand 6monographs. floodplains, andriver valleys. Hehaspublished170scientific channel processes andecological conditionsofriver channels, and regionalizationcartography basedonriver- ofterritories field offormation anddevelopment ofriver floodplains, State Pedagogical University. inthe Heisaleadingexpert ofPhysical GeographyDepartment andGeoecology, Moscow CHERNOV, Aleksey V. ofGeography, isDoctor Headof the CaspianSea.Dr. hastaughtacore course Rychagov development andforecast – reservoir oftheendorheic to theresearchmade avaluablecontribution ofthe oftheCaspianBasin.Hehasand geomorphology around inthefieldsofpaleogeography theworld Federation.” inRussiaand expert Heisawell know title “Honored Worker ofSciencetheRussian State University.Moscow Dr. hasthehonorary Rychagov Paleogeography, Faculty ofGeography, M.V. Lomonosov full Professor, and ofGeomorphology Department RYCHAGOV, Georgy I. and development ofrelief anddeltaplains, and geochronology ofdeltassediments, structure, genesis deltas,river whichcovers sedimentsaccumulation, branch ofscience, i.e. of dynamicgeomorphology He hascreated andsuccessfullydeveloped new ofcoastalzonegeomorphology andriverdeltas. University. inthefieldof Heisaprominent expert Faculty ofGeography, M.V. Lomonosov State Moscow ofSoilErosion ChannelProcesses, andRiver Laboratory Leading Research Scientist,ScientificResearch KOROTAEV,N. Vladislav is Doctor ofGeography, isDoctor is Doctor ofGeography,is Doctor . Changes oftheCaspianSea , 2, Geomorfologiya Moscow, Nauka 50.0016:19:26 16:19:26 05.08.2010

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