Geomorfologiâ i paleogeografiâGeomorfologiâ i paleogeografiâГеоморфология и палеогеография2949-17892949-1797The Russian Academy of Sciences66068110.31857/S2949178923030052WDAEYYSHORT COMMUNICATIONSНАУЧНЫЕ СООБЩЕНИЯUnknownSedimentary characteristics of baer knolls deposits in the volga river deltaЛИТОФАЦИАЛЬНОЕ СТРОЕНИЕ И УСЛОВИЯ НАКОПЛЕНИЯ ОТЛОЖЕНИЙ БЭРОВСКИХ БУГРОВ СЕВЕРНОГО ПРИКАСПИЯ1LobachevaD. M.ЛобачеваД. М.lobachevadm@my.msu.ruBadyukovaE. N.БадюковаЕ. Н.lobachevadm@my.msu.ruMakshaevR. R.МакшаевР. Р.lobachevadm@my.msu.ruLomonosov Moscow State University, Faculty of GeographyМосковский государственный университет имени М.В. Ломоносова, географический факультет01072023543678022022025Copyright ©; 2023, D.M. Lobacheva, E.N. Badyukova, R.R. MakshaevCopyright ©; 2023, D.M. Lobacheva, E.N. Badyukova, R.R. Makshaev2023D.M. Lobacheva, E.N. Badyukova, R.R. MakshaevD.M. Lobacheva, E.N. Badyukova, R.R. Makshaevhttps://journals.eco-vector.com/2949-1789/article/view/660681

Baer knolls (BK) are elongated ridges often close to the sub-latitudinal orientation sometimes spatially isometric that are widespread in the entire Northern Caspian Region up to 0 m a.s.l. (the upper limit of the Late Khvalynian sea transgression). The goal of this study was to establish the genesis of BK based on interpretation of textural and lithologic characteristics of sediments and dating the material composing these landforms. Research has led to the following conclusions that BK have been formed during the transition of Late Khvalynian and Early Holocene time. Sediments of BK consists of three lithofacies (LF1, LF2, LF3). Chocolate clay (CC) and Volga alluvium were significant sources of material for knolls formation. Nonetheless, for lithofacies 1, it was also sandy material lying below the CC. The BK material cannot be attributed to the aeolian genesis because of its lithological, faunal and geochemical characteristics. The knolls formed in brackish subaquatic conditions of the lagoon floor, where a low-energy currents occurred due to the descent of Late Khvalynian basin waters through the Manych Strait. Thus, BK are analogues of river bedforms appearing as the result of turbulent flow, like ripples and river dunes, where, in concordance with the accumulation of sandy material and detritus of redeposited shells, clay particles were deposited under the mixing of the brackish water of the lagoon and the fresh water of the rivers flowing into it.

Бэровские бугры – это, как правило, вытянутые гряды, ориентированные чаще всего близко к субширотному направлению, получившие широкое распространение на территории Северного Прикаспия ниже отметки 0 м абс. Механизм образования этих форм рельефа дискутируется вот уже почти столетие. Данная работа ставит своей целью определение генезиса бэровских бугров на основе структурно-литологических исследований и датирования слагающего их материала. Проведенные исследования позволили заключить, что гряды были сформированы в конце позднехвалынского времени – начале голоцена. Отложения бэровских бугров состоят из трех условно выделяемых литофаций. Основными источниками материала, из которого формировались бугры, являлись шоколадные глины, подстилающие их морские отложения регрессивной террасы и аллювий рек, впадавших в хвалынский бассейн. Данные литологических, фаунистических и геохимических исследований не позволяют считать описываемые формы результатом эолового процесса. Бэровские бугры были образованы на дне лагуны, где существовали течения, обусловленные спуском вод позднехвалынского бассейна через Манычский пролив. Гряды являются аналогами речных дюн, образуемых на дне турбулентного потока, где параллельно с накоплением песчаного материала и детрита шло осаждение глинистых частиц в условиях смешения солоноватых вод лагуны и пресных вод рек, впадающих в нее.

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