978-1-4673-1414-5/12/$31.00 ©2012 IEEE

Marine deposits in Vistula and Curonian Spits (Baltic sea)

Badyukova E.N., Zhindarev L.A., Lukyanova S.A., Solovieva G.D.

M.V. Lomonosov Moscow state university

e-mail: badyukova@yandex.ru

Abstract: Several sea level oscillations were fixed in composition and in the modern morphology (zonal structure) of the Baltic accretive coastal barriers – Curonian and Vistula Spits. Marine sediments were found in deep blow-outs of both spits and in ancient sand beach ridge near Kosa settlement of Vistula Spit. These sediments are corresponding to one of the last peaks of Limnea transgression.

I. INTRODUCTION

The geomorphologic structure of the accumulative barriers bordering many of the world coasts demonstrates close connection of their formation with sea level changes. Such dependence is traced by analysis of a structure of the southeast Baltic sandy barriers - Curonian and Vistula Spits [1-3]. Sea-level fluctuations define not only appearance of these huge accretive features, but also their morphological transformation by aeolian processes to the modern shape. Middle Holocene when Lithorina transgression slowed down during a climatic optimum was the optimal time for development of barrier landforms. The abundance of glacio-fluvial and alluvial sediments on the shelf had predetermined active formation of transgressive barriers along river delta edges. This process occurred repeatedly and had global character. In the Baltic Sea, it gave rise to formation of Curonian and Vistula Spits and the gulfs behind them on the places of impounded river mouths.

II. RESULTS AND DISCUSSION

The subsequent transgressive-regressive sea-level fluctuations are fixed in the zonal structure of barriers: in alternation of longitudinal aeolian ridges divided by aeolian-marine plains accreted during the periods of marine regressions (Fig.1, 2). Traces of several oscillations of such kind were found in the modern barrier morphology. From the seaside behind the sand beach the following morphological zones are found: the zone of modern aeolian accumulation (avandune), aeolian ridge, zone of parabolic dunes. Presence and character of the coastal aeolian features reflect the rates of the coastal zone supply with sand. Axial parts of the barriers are occupied by sandy plains, which are separated from gulfs by high ancient aeolian ridges. Fragmentarily, the near-gulf terraces (1.5 m abs.) and beaches are found.

Fig. 1. Geomorphology of the Curonian Spit (central part). Legend: 1 – beach; 2 – avandune; 3 – dune ridge; 4 – lowland; 5 – marine-aeolian plain; 6 – high dunes; 7 – ancient dunes; 8 – marine-aeolian plain of the gulf coast; 9 – gulf terrace and beach; 10 – cliff.

Fig. 2. Geomorphology of Vistula Spit. Legend: 1 –avandune; 2 – dune ridge; 3 – marine-aeolian plain, “palve”; 4 – lowland; 5 – high dunes; 6 – part of ancient deltaic plain; 7 – blowouts; 8 – cliff.

It is worth to note that hydrogen factors alone generate beaches and near-gulf terrace only. In other morphological zones sediments are reworked by aeolian processes. More than 150 samples of the sand deposits from morphological zones of the Spits have been analysed (Fig.3). It was proved that aeolian sand lies to the depth of 2m below m.s.l. Hence the spits were formed when the sea was lower by 3 or even 4 m.

Fig. 3. Granulometric composition of the sand deposits: а) – аeolian deposits of Curonian Spit.

б) – beach and marine-aeolian plain (“palve”) deposits of Curonian Spit; в) – beach and marine-aeolian plain (“palve”) deposits of Vistula Spit. Legend: 1 – aeolian sand; 2 – marine-aeolian plain (“palve”) deposits; 3 –marine beach deposits; 4 – lagoon beach deposits.

The subsequent sea-level rise has led to the beach ridges formation, by combined coarse-grained sand with pebbles and shells of marine mollusks. Fragments of this coastline have been found out in the Curonian and Vistula Spits. On the sea coast of spits there are the layers of pebbles in the bottoms of some blow-outs. These layers can serve as age analogue of lagoon terrace. The blow-outs strip is situated in the zone of the most active deflation of the coastal sand and located directly behind the dune ridge. The pebble layers fix, apparently, position of an ancient coastal bar, which was primary burred by sand, and then excavated by the modern processes of deflation. The present pebble layers position exceeds a modern sea level by 1.5 - 2 m above m.s.l. near settlements Khvoinoe and Morskoe (Fig.4).

Fig. 4. Coarse sand with mollusks shells near settlement Morskoe and pebble layers near Khvoinoe

The most obvious proof of presence along Vistula Spit the ancient coastline connected to a sea-level rise is the beach ridges traced in the cliff foot in area of settlement Kosa (Fig 5). The ridge consists of light grey coarse-grained layered sand with pebbles, mollusk shells and gastropods. Internal part of a bar is buried under aeolian deposits and another one is opened in cliff extended in this part of spit on some kilometers.

Fig.5. Coastal bar under aeolian deposits near settlement Kosa

Similar marine sand is found out and on other sites of Vistula Spit sea coast. Frequently the presences of marine deposits at the foot of cliff are hided under aeolian deposits. The layer of beach deposits with pebble and mollusk shells was found in 2 km to southwest from the settlement Kosa under deposits of dune ridge. Sometimes in these deposits thin interlayer of heavy minerals observe, that unequivocally speaks about their formation on the berma

surface of an ancient beach. These deposits contain interlayer of garnets (2-3 cm) and glauconite (1-2 cm) appreciably inclined aside the sea (Fig. 6).

Fig. 6. Interlayer of garnets

On the basis of the mollusk shells dating 14 C from the marine deposits composing the bottom part of a cliff their

age 1270+60 cal BP (LU-6129) has been received. Position of the bar concerning to the coastline let to consider that sea-level was on 0.5 m higher than the contemporary one. Lagoon terrace was formed at the same time. Ancient coastline and terrace are corresponding to one of the last peaks of Limnea transgression.

REFERENCES

[1]. E.H. Badyukova, L.A. Zhindarev, S.A. Lukyanova, G.D Solovieva, “ Geological structure of the Curonuan Spit (of the Baltic Sea) and its evolution history (revised)”, Oceanology, vol. 47, № 4, pp. 594-604, 2007. [2]. E.H. Badyukova, L.A. Zhindarev, S.A. Lukyanova, G.D Solovieva, “Barrier-lagoon systems in the south-east of the Baltic Sea”, Oceanology,

vol. 48, № 4, pp. 37-48, 2008. [3]. E.H. Badyukova, L.A. Zhindarev, S.A. Lukyanova, G.D Solovieva, “Geological and geomorphologic structure of the Baltic (Vistula) Spit”

Oceanology, vol. 51, № 4, pp. 675-682, 2008.