Biostratigraphy of the Marine Holocene on the Iranian Coasts of the Caspian Sea

Quaternary International xxx (2014) 1e8

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Biostratigraphy of the Marine Holocene on the Iranian coasts of the Caspian Sea

* A.A. Svitoch, E.N. Badyukova , T.A. Yanina, B. Sheikhi article info abstract

Article history: Marine Holocene deposits of the coast of Iran are represented by the Upper Khvalinian and New Caspian Available online xxx beds. Upper Khvalinian sediments are faunistically barren, whereas the New Caspian beds contain abundant fossil molluscs that allow subdivision into the Daghestan, New Caspian and modern layers. The Keywords: only fossil species found in the Daghestan layer is Didacna cristata. The New Caspian sediment layer is Holocene characterized by a taxonomically diverse molluscan assemblage dominated by Cerastoderma glaucum.It Coast of Iran is subdivided into the Upper and Lower New Caspian sub-layers. Modern sediments are lithologically Biostratigraphy diverse. Besides the New Caspian fauna, they also contain the valves of the species Mytilaster lineautus Malacofauna which is known to have immigrated from the Black Sea. © 2014 Elsevier Ltd and INQUA.

1. Introduction Recently, investigations of the Caspian coast in Iran have been conducted using palynological, lithological, and geochronological The Iranian coast of the Caspian Sea lies within the limits of the methods. A series of studies has been performed on the charac- South Caspian lowland bounded by the Elburz Range on the south teristics and facies type of sedimentation, as well as on vegetation (Fig. 1). Structurally, the plain corresponds to the Pre-Elburz and climatic events during the Holocene (Kazanci et al., 2004; Foredeep filled with Neogene-Quaternary deposits and separated Lahijani et al., 2005, 2009; Leroy et al., 2011). Some significant by a deep-seated fault from the Elburz folded zone. Geo- data have been obtained on the recent sea level fluctuations and morphologically, it is a vast lowland gently sloping towards the sea their chronology, on the development of the Sefidrud River delta from 20 to À27 m a.s.l. The surface of the coastal plain forms a series and surrounding low-lying plain through the Holocene (Richards of poorly developed terraces separated from the modern beach by a et al., 2011; Kakrodi et al., 2012; Kazanci et al., 2013). All those series of beach ridges. Some of the ridges separate lagoons from the studies, however, are lacking a biostratigraphic basis to support the sea. The largest of the lagoons are Anzali and Gorgan Bay. The rear subdivision of sedimentary sequence. part of the lowland adjoins a narrow zone of low foothills. fi The surface of the coastal plain is composed of diversi ed marine 2. Material and methods of the studies deposits dated to the Holocene. Biostratigraphy of the marine sediments has not been adequately studied as yet on the Caspian coast of The studies were based on field surveys performed on the Ira- fi Iran. In particular, there is no paleontological data (speci cally, those nian coast of the Caspian Sea in 2005 and 2011. In 2005, the authors on mollusks) to serve as a basis for subdivision of the sequence and participated in the international conference “Rapid Sea Level its correlation with other coasts. That may be due to the fact that Change: a Caspian Perspective” (Rasht, Iran). A reconnaissance mollusk shells are scarce in the marine sediments in the region, and survey of the Quaternary sections on the Mazandaran and Golestan fi their collections are scanty and insuf ciently studied. There are no coasts was performed during the field excursions as a part of the works on the Iranian coast giving detailed layer-by-layer de- conference work (Svitoch and Yanina, 2006). In 2011, the coastal scriptions of sediments exposed in marine terrace scarps or in river sections and river valleys on the Gilan and Mazandaran plains were valleys; the only exception is Ehlers (1971). Practically no key sec- studied in more detail (Svitoch et al., 2013), along with a compre- tions, necessary objects for stratigraphic studies, are known at pre- hensive analysis of the literature. We applied the multidisciplinary sent. In searching for such sections, it is essential that the natural approach, including biostratigraphic (malacological) analysis, as exposures were accessible for repeated studies. well as a systematic layer-by-layer description of natural sections exposed by marine and fluvial erosion. Another method that could * Corresponding author. Krasny Kazanez, 19-1-228, Moscow, Russian Federation. be really effective in studies of the Iranian coast stratigraphy is a E-mail addresses: [email protected], [email protected] (E.N. Badyukova). layer-by-layer description of the most complete natural exposures http://dx.doi.org/10.1016/j.quaint.2014.05.047 1040-6182/© 2014 Elsevier Ltd and INQUA.

Fig. 1. Iranian coast of the Caspian Sea. Regions: 1 e Astara-Resvanshabr; 2 e Anzali-Rudsar; 3 e Ramsar-Noor; 4 e Noor-Miankalen; 5 e Golestan. Location of key sections: 2.1 e River Khovig mouth; 2.2 e right bank of the Karganrud R.; 2.3 e right bank of a channel on the Golestan coast; 2.4 e rear part of the bar separating the Anzali lagoon from the sea; 2.5 e seaside part of the bar.

and tracing characteristic features along the strike from one section Mangyshlak regressive stage between them. Unlike their analogs to another. In the process, there may be identified some reference on other Caspian coasts, the Khvalynian sediments are practically horizons rich in materials for analyses. This method is still one of barren of mollusk shells and are mostly identified on the basis of the most effective and reliable in geological investigations and has their hypsometric position, geomorphological, and lithological been widely used in our work, along with radiocarbon dating, as characteristics. The New Caspian deposits, on the other hand, well as lithological and geomorphological data were used, with due abound in malacofauna that can form the basis for biostratigraphic consideration for hypsometric position of the studied objects. subdivision of the sequence. Eleven mollusk species belonging to 6 genera have been iden- 3. Results of the studies and discussion tified in the Holocene sediments (Table 1), with Cerastoderma glaucum (Cardium edule) being dominant. Quite frequent are 3.1. Paleontological substantiation (analysis of malacofauna) Didacna shells (Didacna сrassa, Didacna. praetrigonoides, Didacna trigonoides, Didacna pyramidata, Didacna. сristata), and less com- The Holocene deposits on the Iranian coast are attributed to the mon are Dreissena polymorpha, Monodacna caspia, Adacna lae- Khvalynian (final phase) and New Caspian transgressions, with the viuscula, and Мytilaster lineatus are found occasionally. The

Table 2 The Caspian molluskus distribution over the sequence of New Caspian deposits.

Holocene sequence on the Iranian coast, there are Upper Khvaly- 1) dark brown sandy loam, weakly humified, with plant remains, nian and Mangyshlak deposits overlain with New Caspian sedi- 0.1 m thick; ments with characteristic mollusk fauna. The Holocene sequence 2) gray fine grained sand, with small-size shell detritus in abun- overlies the lower part of the Khvalynian horizon. dance; less common are large fragments and intact shells of C. The Khvalynian horizon includes lower and upper Khvalynian glaucum, D. crassa, etc; layers. The lower Khvalynian layers are found in foothills where 3) dark gray sand fine grained, with small-size detritus, larger they occur as a thin sedimentary cover on the Caspian terraces at fragments and entire shells of C. glaucum; altitudes 50 to 0 m a.s.l (Svitoch et al., 2012). The layers are mostly 4) the layer consists of alternating thin (2e4 cm) laminae of well composed of red-brown clays and silts devoid of mollusk shells, rounded gravel, pebble, and coarse sand including shell mate- only rare fragments of the latter being found occasionally in con- rial. The upper part of the layer is dominated by non-sorted glomerates (Ehlers, 1971). The Upper Khvalynian layers occur at the sand, the lower boundary is sharp and well traceable by rear part of the coastal plain at 0 to À20 a.s.l. The layers did not yield change in lithology. The total thickness is 2.0e2.5 m. This unit any Caspian malacofauna. serves as a marker bed; it may be easily traced along the strike The Mangyshlak layers correspond to the epoch of the deep as far as the river mouth. Characteristically, it contains Mangyshlak regression, recorded also on other Caspian coasts and numerous shells of C. Glaucum, some D. crassa, D. trigonoides, dated to approximately 7.2e6.4 ka BP (Svitoch, 2006); a major part occasional M. caspia and D. polymorpha. Its radiocarbon age is of the Caspian shelf was drained at that time. The Mangyshlak 940 ± 50, or 860 ± 60 cal. BP (LU-6877); deposits are widespread on the Iranian coast. Lithologically, they 5) whitish-gray fine-grained sand, well sorted, with C. glaucum are dominated by coarse clastic deposits and fluvial sands forming shells in abundance, more rare D. polymorpha, and occasional M. deltas and fans of intermittent streams. caspia and D. trigonoides. In the lower part of the layer gravel and Sediments of the New Caspian horizon are widespread over the pebble occur as interlayers and lenses. The entire layer is 1.5 m near-coast zone. Unlike the underlying formations, they contain thick. abundant fauna of marine mollusks that may be subdivided into 6) fine sand, dark gray to black, with rare shell fragments in the three major faunistic complexes. The complexes serve as a basis for lower part; the boundary is lithologically distinct; thickness identifying three stratigraphic units e Daghestanian, New Caspian 0.5 m; and recent layers. Daghestanian sediments, a stratigraphic unit 7) compact densely packed remains of hydrophilic and water qualified as layers, were first identified in sections of Daghestan plants; along the strike they are gradually replaced with silty (Svitoch, 2006). The studies revealed a typical New Caspian Didacna sand, bluish gray, 0.5 m thick, with bivalve D. сristata shells in assemblage dominated by « crassa » and « trigonoides » groups, but abundance; the boundary is sharp. The 14C age is 460 ± 60 BP, or devoid of C. glaucum. Seemingly, the latter, though considered an 460 ± 90 cal BP (LU-6878); index species for New Caspian sediments, had not penetrated into 8) boulders in a matrix of gravel and pebbles, apparent (exposed) the Caspian Sea by that time. On the Iranian coast, analogous sed- thickness is 0.3 m. iments supposedly occur at the base of the key section on the left side of the Khavig River mouth (Fig. 2). The section is described as At the river mouth, the sediments of layer 4 are seen to be cut follows (from top downward): and overlain with gray sands of the beach barrier containing shells

Fig. 2. Key sections of the New Caspian deposits (for the location see Fig. 1). Legend: 1 e silt, 2 e sand, 3 e gravel, 4 e pebble and boulders, 5 e aeolian sands, 6 e fossil soils, 7 e mollusk shells, 8 e plant debris, 9 e discontinuity (sedimentation gap).

Aside from various terrigenous facies, there are fine sediments 1) dark gray and gray non-sorted sand, mostly coarse, with a great deposited in shallow stagnant water and freshened lagoons quantity of small-size gravel and pebble of various sizes ar- commonly found among the lower New Caspian formations. To ranged in layers. The uppermost part of the layer is silty brown take one example, in the Neka section (Lahijani et al., 2005), under sand with traces of soil formation. At the base of the layer there the modern soil with plant remains there is a thick (4e6 m) series is a lens of coquina dominated by C. glaucum, with less frequent of organic-rich mud, with mollusk shells in its lower part; the shells D. pyramidata and D. crassa shells. The lower boundary is lith- were dated at 2.4 ka BP. An age close to this one (2.48 ka BP) has ologically sharp and irregular. The 14C dated mollusk shells been obtained for shells recovered from the sand underlying lagoon yielded the age of 0.570 ± 50 ka BP (Svitoch et al., 2006). mud in the Larim section (Lahijani et al., 2005), in the eastern part Thickness is 1.7 m. of the coast. 2) fine-grained sand, brown-gray to dark gray and yellow-brown, An interesting section was described on the Golestan coastal 0.1 m thick (lagoon deposits); lowland (Svitoch et al., 2006) situated on the right bank of a 3) brown coquina with fine sand matrix. Among mollusk shells, channel separated by a barrier beach from the sea (see Fig. 2): dominant are D. polymorpha, also frequent are C. glaucum and M. caspia. The layer was deposited in a shallow fresh-water lagoon. 1) yellowish-gray sandy silt, slightly reworked by soil-forming Thickness is 0.1 m. (Deposits of a shallow fresh-water lagoon processes at the top, 0.8 m thick; with freshened water); 2) dark brown sandy silt, compact, with rare small-size shells of 4) dark gray non-sorted sand, mostly of medium and small grain freshwater gastropods; bluish-gray interbeds in the middle part size, with gravel and rare small pebbles; pebble interbeds occur of the layer suggest weakly pronounced processes of hydro- at the base; the upper part is colored with iron oxides; the morphic soil formation; thickness is 0.6 m apparent thickness is 1.5 m (littoral deposits).

The exposed series is composed by sediments attributable to pebbles. Typical is diagonal bedding, with oblique beds dipping in three cycles of deposition. Judging from the mollusk fauna, the accordance with inclination of the topographic surface. Along with upper (layer 1) and the lower (layer 4) units are littoral formations abundant shell detritus, there are intact shells of C. glaucum of a basin with a normal Caspian salinity (12e14‰). They are (dominant), D. сrassa, D. trigonoides, M. caspia and D. polymorpha.In separated with units deposited in a freshened lagoon (layers 2, 3), some more complete sections, there are lagoon sediments at the occasionally salinized or dried up (the latter is indicated by signs of base, consisting of clayey silts and silty sands, gray and bluish-gray, soil formation). with C. glaucum. At the top the sediments are often reworked by The maritime part of the bay bar has been studied in a sand wind and weathering. The apparent thickness of the upper part of quarry 0.1 km to the north (see Fig. 2): New Caspian deposits does not exceed 1.5e2 m. The final stage of the New Caspian epoch was marked by aeolian sand formation over 1) gray and dark gray non-sorted sand, with horizontal interbeds the soils on the New Caspian marine terrace. The soils developed of fine or coarse sand, with traces of soil formation at the top; after the sea had finally retreated from the surface. Floodplain de- thickness is 1.0 m; posits and deltas of numerous rivers crossing the coastal plain are 2) non-sorted sand, predominantly coarse, abounding in pebbles, also dated to the same time. with diagonal bedding or cross lamination, the beds sloping A series of 14C dates have been obtained for New Caspian sedi- towards the rear part of the bar; rare fragments of Cerastoderma ments recently (Lahiani et al., 2009; Leroy et al., 2011; Kokrodi et al., shells are present; exposed thickness is 3.0 m. 2012; Svitoch et al., 2006, 2013)(Table 3). To estimate the age of marine New Caspian sediments on the Iranian coast, we analyzed Unlike the above described section, there are exposed two the radiocarbon dates obtained on marine mollusk shells (Fig. 3). members of coarse clastic littoral deposits in the sand quarry on the When considering the distribution of dates over time, three groups bay bar. Seemingly, they correspond to the 1st and 3rd cycles of may be identified, namely: 6.5e5.5, 3.7e2.3, and 0.9e0.3 ka BP, deposition in the back part of the bay bar. No lagoon sediments each group corresponding to a transgressive stage and its deposits were found. The uppermost part of the New Caspian layers making (Daghestanian, lower New Caspian and upper New Caspian). Taking the barrier beach is simpler in structure and composition. Those are into account the fact that the dates were obtained using different mostly gray and dark gray sands varying in grain size, with well- variants of the radiocarbon method (scintillation and AMS) and sorted fine varieties prevailing. They are often thinly bedded due different procedure of calculation (calibrated and uncalibrated to the presence of coarse sand, gravel and small-size well-rounded dates), the obtained age of New Caspian transgressions and biostratigraphic units should be taken as conventional. Analysis of the dates in comparison with radiocarbon chronology of other Caspian coasts (Svitoch, 2006) suggests the oldest group of dates (6.5e5.5 ka BP) corresponds to the age of the Daghestanian transgression, the medium group (3.7e2.3 ka BP) e to deposits of the lower New Caspian stage, and the dates 0.9e0.3 ka BP belong to the late New Caspian stage of the transgression.

Table 3 Radiocarbon dates of the New Caspian deposits on the Iranian coasts of the Caspian Sea.

14C dates (ka BP) Source

0.34 ± 60 Svitoch et al., 2006 0.57 ± 50 Svitoch et al., 2006 0.460 ± 60 Svitoch et al., 2013 0.940 ± 50 Svitoch et al., 2013 0.491 ± 35 Lahijani et al., 2009 0.908 ± 35 Lahijani et al., 2009 2.400 ± 50 Lahijani et al., 2009 2.480 ± 50 Lahijani et al., 2009 2.455 ± 50 Ehlers, 1971 2.415 ± 50 Ehlers, 1971 0.956 Kakrodi et al., 2012 0.960 Kakrodi et al., 2012 2.303 Kakrodi et al., 2012 3.369 Kakrodi et al., 2012 5.990 Kakrodi et al., 2012 0.290 Leroy et al., 2011 0.440 Leroy et al., 2011 0.379 Leroy et al., 2011

Earlier similar age estimates for the upper New Caspian transgression stage and its deposits were obtained by (Svitoch et al., 2006). Time intervals having no dates of marine sediments (older than 6.5, 5.0 to 4.0, and 2.0 to 1.0 ka BP) might correspond to regressive stages noted for a very complicated history of the coastal Fig. 3. Distribution of radiocarbon dates over the sequence of marine New Caspian drainage system and deposition of diversiﬁed continental forma- deposits. 1e5 e sources: 1 e Kakrodi et al., 2012;2e Leroy et al., 2001, 2011;3e ﬁ Lahijani et al., 2009;4e Ehlers, 1971;5e Svitoch et al., 2006;6e layers : A e Dag- tions, as has been considered in detail by the example of the Se - hestanian, B e lower New Caspian, C e upper New Caspian. drud delta (Svitoch et al., 2006).

Typically, the entire mollusk-bearing New Caspian sequence is silts or clayey sands with mollusk shells of various species. In- highly diversified in marine facies and lithology, with various al- terbeds of compact plant remains are found occasionally. luvial, eolian and soil formations between the marine units. The The Recent layers unit is diversified in composition and includes latter are lagoon and littoral formations, including facies of calm marine sediments of the low marine regressive terrace formed and dynamic shallow water and beach facies. The calm shallow sea during the lowstand of the Caspian Sea (1929e1977), as well as facies is composed of well sorted, primarily fine-grained sand, with beach deposits; fluvial deposits (channel and floodplain facies); obvious or obscure layering, horizontal or diagonal. The sand in- eolian deposits; and soils. A major part of the recent deposits is cludes small detritus in abundance (which often imparts light gray highly variable in lithology and facies as a result of changeable color to it), and various mollusk shells occurring at random or ar- environments of sedimentation. ranged in layers. The dynamic littoral facies displays coarser li- Heavily eroded in the period of rising sea level (1977e1995), the thology, dominated by non-sorted sands and fine gravel with regressive terrace surface presents a series of low beach bars pebble interlayers. Less common are pebbles and cobbles arranged composed of less coarse material than the New Caspian bars. The in distinct layers, noticeable due to distribution of rock debris of deposits of the recent bars are mostly medium to fine-grained assorted sizes, shell fragments, and intact mollusk shells. sands with a small admixture of pebble and gravel material, Lagoon sediments are found most often at two altitudinal detritus and shells of mollusks: D. сrassa, D. trigonoides, levels: À22 to À24 m and À25 to À26 m, occurring at the base of D. praetrigonoides, M. caspia, A. laeviuscula, D. polymorpha, domi- lower and upper New Caspian levels. Dominant are gray and bluish- nant C.glaucum and occasional M. lineatus. At the time of the last sea gray muds, varying in proportions of silt and sand. Less common are level rise, some lagoons formed at the rear part of the terrace; at

Fig. 4. Biostratigraphic scheme of the Holocene deposits at the Iranian coast of the Caspian Sea.

Please cite this article in press as: Svitoch, A.A., et al., Biostratigraphy of the Marine Holocene on the Iranian coasts of the Caspian Sea, Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.05.047 8 A.A. Svitoch et al. / Quaternary International xxx (2014) 1e8 present some of them are filled with water, while others are dried from the overlying subunit. The upper New Caspian sediments up. Waves locally eroded the terrace edge and formed a scarp with a form the low marine terrace above À20 m and some large barrier modern beach fringing its base. bars separating vast lagoons from the sea. Those sediments contain The beach sediments are highly variable in composition mollusks of the late New Caspian subcomplex. depending on the beach morphology and dynamics. Lithologically, The recent layers occur at the top of the New Caspian horizon on they are dominated by sand with well-rounded grains. The pro- the Iranian coast. They consist of deposits different in lithology and portion of coarse material depends directly on the beach charac- facies (beach, lagoon and shallow and deeper sublittoral). The facies teristics: the steeper is its surface and smaller the width, the correspond to environments of sedimentation that existed in the coarser material it is composed of. The presence of pebble on the nearshore zone under conditions of repeatedly changing climate, beach in abundance is mostly due to numerous river distributaries. hydrology, and rhythmic sea level fluctuations. The recent layers Most common are wide beaches composed of well sorted sand, all contain various members of the faunal complex with an invader located at the mouths of large rivers. Locally, where the Elburz from the Black Sea, M. lineatus, as the index species. At present foothills near the sea, beaches are usually narrow and composed of anthropogenic factors exert an increasingly pronounced effect on coarse material. Fauna in beach deposits (the modern complex) is the sedimentation and relief-forming processes. relatively abundant and diversified, including M. lineatus missing from older deposits. Acknowledgments Lithological and facial structure of the Holocene deposits of the Iranian coast and malacofauna reflect rhythmics of the last trans- The authors are grateful to Kh.A. Arslanov for providing the gressive stage of the Caspian Sea which has begun after the Man- radiocarbon analysis of the samples, to I.I. Spasskaya for her help in gyshlak regression. At the beginning of a stage (6.5e5.5 thousand the text editing and translating, and to R.R. Makshayev for drawing years?) the Daghestan ingression was noted. It formed the exten- figures. The investigations were conducted with financial support sive lagoons in the depressions of the low coast. Later (3.7e2.3 from the Russian Foundation for Basic Research (grants 13-05- thousand years) there was a maximum of the New Caspian trans- 00086, 14-05-00227). gression. Its deposits compose the low coast to À20.0 m a.s.l. Transgression ended 0.9e0.3 thousand years ago, when the low (the first) Caspian terrace was formed. References The varied facies structure of the New Caspian deposits in- € dicates involved hierarchical rhythms of sea level fluctuations. The Ehlers, E., 1971. Südkaspisches Tiefland (Nordiran) und Kaspisches Meer. Beitrage zu ihrer Entwicklungsgeschichte im Jung- und Postpleistozan.€ Tübinger Geo- fallings of level of the Caspian Sea with different amplitude are graphische Studien 44 (5), 184. noted in the Holocene deposits by alternation of layers of marine Kakrodi, A.A., Kroonenberg, S.B., Hoogendoorn, R.M., Mohammad Khani, H., deposits, lagoon or alluvial sediments, washout traces, or soil Yamani, M., Ghassemi, M.R., Lahijani, H.A.K., 2012. 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Daghestanian, New Caspian, and recent layers. The Upper Khvaly- Lahijani, H.A.K., Sharifi, A., Tavakoli, V., 2005. Evidences of the late Holocene sedi- nian layers on the Iranian coast are not characterized by a specific mentation along the coast of the southern Caspian Sea, Iran. In: Rapid Sea Level faunal complex. They are identified by geomorphic, hypsometric, Change, a Caspian Perspective. Proceeding of the International Conference (2-9 May, Rasht, Iran). University of Guilan Press, Rasht, pp. 62e64. and lithological data. Leroy, S.A.G., Lahijani, H.A.K., Djamali, M., Naqinezhad, A., Moghadam, M.V., The New Caspian horizon contains abundant mollusk fauna Arpe, K., Shah-Hosseini, M., Hosseindoust, M., Miller, ChS., Tavakoli, V., which makes possible biostratigraphic subdivision of the horizon Habibi, P., Naderi Beni, M., 2011. Late Little Ice Age palaeoenvironmental records from the Anzali and Amircola lagoons (south Caspian Sea: vegetation and sea into layers. By layer-by-layer study of natural exposures, compre- level changes. Palaeogeography, Palaeoclimatology, Palaeoecology 302, hensive analysis of mollusk fauna, and with due regard for 415e434. geomorphic position, Daghestanian, New Caspian and recent layers Richards, K., Leroy, S.A.G., Arpe, K., Marret, F., Hoogendoorn, R.M., Kroonenberg, S.B., fi 2011. Fluctuations in Caspian Sea level During the Quaternary: New Evidence were identi ed within this horizon (Fig. 4). from Palynology and Climate Modeling. Abstracts. INQUA Congress. Bern. The Daghestanian layers occur at the base of the sequence and Svitoch, A.A., 2006. Hierarchy and chronology of the Caspian Sea level fluctuations overlie the Mangyshlak regressive deposits (layers). They are during the Holocene. In: Changes of Natural Territorial Complexes within the Regions Subjected to Anthropogenic Impact. Media Press, Moscow, pp. 125e133 mostly lagoon facies and contain solely D. cristata shells belonging (in Russian). to the Daghestanian faunistic complex, whereas C. glaucum, the Svitoch, A.A., Badyukova, E.N., Kroonenberg, S.B., Parunin, O.B., Vonhof, H.I., 2006. index species of the New Caspian layers, is completely absent. Radiocarbon Dating of Mollusk Shells from Marine Sediments of the Dagestan The New Caspian layers feature a diversified mollusk fauna Coast of the Caspian Sea (The Turaly Area), vol. 3. Vestnik Moskovskogo Uni- versiteta. Ser. Geogr, pp. 13e21 (in (Russian)). known as the New Caspian faunal complex with C. glaucum as the Svitoch, A.A., Badyukova, E.N., Sheikhi, B., 2012. Stratigraphy of the Recent Deposits index species. The stratigraphic unit of the New Caspian layers is at the Iranian Coast of the Caspian Sea, vol. 6. Vestnik Moskovskogo Uni- e subdivided into lower New Caspian and upper New Caspian sedi- versiteta. Ser. Geogr, pp. 68 77 (in (Russian)). Svitoch, A.A., Badyukova, E.N., Sheikhi, B., Yanina, T.A., 2013. Geological-geomor- ments based on the presence of a certain faunal subcomplex, early phological structure and the recent history of the Iranian coast of the Caspian or late New Caspian, as well as on the geomorphic context and Sea. Doklady RAN 451 (4), 451e457 (in Russian). position in the sequence. The lower New Caspian sediments occur Svitoch, A.A., Yanina, T.A., 1997. Quaternary Deposits of the Caspian Sea Coasts. À À Rosselkhosacademiya Publ., Moscow, 268 pp. (in Russian). on the coastal plain at 20 to 24 m and contain a faunal sub- Svitoch, A.A., Yanina, T.A., 2006. Holocene marine sediments of the Iranian coast of complex much richer in species composition than that recovered the Caspian Sea. Doklady RAN 410 (4), 271e276 (in Russian).