Sea level changes and coastal evolution in the south-eastern Baltic Sea L. Ž. Gelumbauskaitė, J. Šečkus Institute of Geology and Geography T. Ševčenkos str. 13, LT-03223 Vilnius, Lithuania The studying object is south-eastern Baltic Sea and its coasts including three countries Lithuania, Russia (Kaliningrad district) and Poland. Aim of the work is possible to separate into three parts: 1. Creation of 4D (space/time) geological model for south-eastern Baltic Sea in Late-Glacial - Holocene (last 13 500 years); 2. Comparison of long term and short term (Postlitorina) relative sea level changes; 3. Prognostic scenarios of the south-eastern Baltic Sea (about 700 years). The 4D model includes three main components. First, a digital elevation model (DEM 0 ) describing the recent state of coastlines and the elevation of adjacent areas is needed. This structural model has to include both bathymetry and land relief. Second data describing the eustatic component of sea level variations have to be provided by climate modellers. Third, vertical movements of the earth s crust have to be taken into account (Meyer 2003, Meyer et al. 2005) (Fig. 1). eustasy isostasy structural model databas sediment dynamics 4D GIS MODEL PROCES SING palaeo scenarios prognostic scenarios Fig. 1. Scheme of geological modelling (after Meyer, M.). It is possible to describe the elevation model in time using formula (in case of t<0): DEM t = DEM 0 + SED E/D + RSL t DEM t elevation model in time; SED E/D sediments affected by erosion/deposition; RSL t relative sea level changes. Relative sea level changes can be described: RSL t = EC t + IC t EC t Eustatic component (mainly caused by climatic factor); IC t Isostatic component (mainly caused by tectonic movements of earth crust).
For future scenarios formula will be used (in case of t>0): DEMt = DEM0 + SEDE/D + ECt + ICt Digital Elevation Model (DEM) Digital Elevation Model for the south-eastern Baltic Sea area is compiled using various data sources: Elevation data of Lithuania mainland up to 21 30 E (GIS Centre data, Vilnius); Bathymetry of Baltic Sea (Gelumbauskaitė 1996); GTOPO30 (United States Geological Survey 1996). Digital elevation model is created using krigging interpolation method in Surfer program, where horizontal resolution is 50 m and vertical - 1,0 m (Fig. 2). Fig. 2. Digital elevation model of south-eastern part of the Baltic Sea.
Data about erosion/deposition processes (SED E/D ) Geophysical (echosounding, seismoacoustic, etc.) and geological data were collected in 1983-2003 within national marine-maritime geological mapping programs at a scale 1:200,000-50,000 and several international projects. Geoseismic units were interpreted as geological units via interpretation of cores and boreholes where spore and pollen analysis, lithostratigraphical, radiocarbon and OSL dating were performed by different authors. Geoseismic profile offshore and geological profile onshore were compiled together and was got seismogeological profile stretching from West to East through Baltic Sea Curonian Spit - Curonian Lagoon - Lithuanian onshore (about 100 km). The horizontal scale of the profile is at 1:150 000 and vertical - 1:500 (Fig. 3). L 2 BIL BIL max = +6 m (11700±180 14 C) A 2 = -46,5 m (8300 14 C BP) L 3 = +2 m (4500 14 C BP) A 1 L 3 Y max = -55,5 m (9600-9500 14 C BP) L L1 1 = -26,5 m (7800 14 C BP) L 1 A 1 = -5,5 m (8700-8500 14 C BP) L 2 = +5 m (6100 14 C BP) A 2 Y Fig. 3. Seismogeological profile showing transgression-regression peaks (marked by arrows) of different Baltic Sea stages (Gelumbauskaitė et. al. 2005a). Using gyttja and peat dating (Andren 1999, Kabailienė 1997, 1999, Blazhchishin et al. 1974, 1989, Bitinas et al. 2001, 2002) as well as remnants of wood dating (Bitinas et al. 2003, 2004) and geomorphological method of ancient shore formations (Lukosevicius et al. 1974, Blazhchishin et al. 1982, Gelumbauskaitė 1982, 2000, 2002) it has been done curve of relative sea level changes. Relative Sea Level changes (RSL t ) According to the traced geoseismic section, the ancient shore levels of the transgression-regression peaks have been constituted: Baltic Ice Lake maximum transgression (11,700±180 14 C BP) refers to +6 m NN, Y max. transgression (10,000-9,500 14 C BP) to 55.5 m NN, A 1 max. transgression
(8,800 14 C BP) to 5.5 m; A 2 regression peak (8,300 14 C BP) to 46.5 m, L 1- (8,000-7,800 14 C BP) to 26.5 m, L 2 max. (6,100±125 14 C BP) to +5.0 m, L 3 (4,500 4,415±45 14 C BP) to +2.0, PL (4,000 3,500-3,295±50 14 C BP) (Gelumbauskaitė et al. 2005a, b) (Fig. 4). 13000 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 Calendar years, BP 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 Radiocarbon years, BP Allerod.. Younger Dryas Baltic Ice Lake Pre- Boreal Yoldia Boreal Ancylus Atlantic Litorina Sub- Boreal Postlitorina Sub-Atlantic Chronozone Baltic Sea stage BIL +6.0 (11700 + - 180) L +5.0 2 (6010 +- 125) L +2.0 3 PL +2.0 4415 +- 45 + - 3295 50 +10 +5 0 A -5.0 1 8800-5 -14.5 (6930 + - 130) -10-15 -27.0 (9160 + - 60) -30.0 (10360 +- 100) L - 26.5 1 8000-7800 Gyttja with peat dating Remna nts of wo od datin g Peat dating Geomorphological, seismic and litho-biostratigraphical data -20-25 -30-35 Y -55.5 10000-9500 -45.0 9000 A - 46.5 2 8300-40 -45-50 -55-60 Fig. 4. Relative sea level changes in the south-eastern Baltic Sea (Klaipėda traverse), isostatic factor is not separated (Gelumbauskaitė et al. 2005a). Relative sea level curve was compared with other curves compiled by other authors in Lithuania (Kabailienė 1997, Bitinas et al. 2004) (Fig. 5). We found direct correlation of the curves presented in this presentation with curves of the eustatic changes in the North-West Europe and Atlantic Caribbean region (Fairbanks 1989, Mörner 1980) (Fig. 6). Data on short term climate changes Data on short term water level changes in Curonian Lagoon and Lithuanian coast are playing special interest and will help to create prognosis scenarios for coastline changes. South-eastern part of the Baltic Sea belongs to the passive tectonic zone (fixed near Klaipėda, Gudelis 1961, 1982, Frischbutter et al. 1995, Harff et al, 2001), where value of movement amplitude is near 0. Therefore, geodynamic model created in this part of Baltic Sea can be standard to investigate sea level rises caused by climatic factors. Several data sources will be used for modelling: curves of climate changes from Swinoujscie (Poland) to Liepaja (Latvia) (Jarmalavičius et al. 2001) (Fig. 7); content of spores-pollen (Pustelnikovas et al. 1996); chemical composition of sediments (Pustelnikovas et al. 1996).
First results According to our investigations full marine and lacustrine deposition complex prevailed only offshore, until 50m b.s.l., in the existed BIL, Y,A 1-2 and L 1-2-3 propers on the Lithuanian coast. On the shallow, nearshore and onshore, Late-Glacial and Holocene depositional complex is more variable, truncated, caused by fluvial processes. The palaeogeographical conditions and depositional erosional activity of the fresh water basins during Alleröd-Boreal periods have been investigated using created GIS database of the stratigraphical units. Palaeotopography of the till loam top, IL-BIL and A 1-2 Baltic Sea stages is reconstructed and exposed on 3D schemes, revealed deformations and dimension of the morpholithogenetic processes during Late-Glacial and Postglacial time. The curve of the relative sea level changes on the traverse Klaipeda-Dreverna and its correlation with other long-term-short term curves of the eustatic changes revealed conformities and discrepancies in the eustatic mechanism at the latitude Klaipeda on the the Lithuanian coast. References Andrén E. 1999. Holocene environmental changes recorded by diatom stratigraphy in the southern Baltic Sea. Meddelanden fran Stockholms Universitets Institution för Geologi och Geokemi, 302. Bitinas A., Damušytė, A., Hütt, G., Jaek, I., Kabailienė, M. 2001. Application of the OSL dating for stratigraphic correlation of the Late Weichselian and Holocene sediments in the Lithuanian Maritime region. Quaternary Sciences Review 20: 767-772. Bitinas, A., Damušytė, A., Stančikaitė, M., Aleksa, P. 2002. Geological development of the Nemunas River Delta and adjacent areas, West Lithuania. Geological Quarterly, 46 (4): 375-389. Bitinas, A., Žulkus, V., Mažeika, J., Petrošius, R., Kisielienė, D. 2003. Tree remnants on the bottom of the Baltic Sea: the first results of investigations. Geologija, 43: 43-46. Bitinas A., Damušytė, A., 2004. The Litorina Sea at the Lithuanian Maritime region. Polish Geological Institute Special Papers, 11: 37-46. Blazhchishin, A. I. et al. 1974. Pollen and diatom analysis of the 4 bottom sediment cores from the Southern and Central Baltic. Baltica, 5. 119-126. Blazhchishin, A.I. et al 1982. Ancient shore lines and shore formations of the South-eastern Baltic sea. Baltica, 7. 57-64. Blazhchishin, A. I. et al 1989. Peat datingo n the bottom of the South-Eastern Blatic. Abstracts of the VIII Radionuclids and Geochemistry Conference. : 13. Vilnius (in russian). Fairbanks R.G. 1989. A 17,000-year glacio-eustatic sea level record : influence of glacial melting rates on the Younger Dryas event and deep ocean circulation. Nature. 342 637-642. Frischbutter, A., Schwab, G. 1995. Karte der rezenten vertikalen Krustenbewegungen in der Umrahmung der OstseeDepression. Ein Beitrag zum IGCP Projekt Nr. 346: Neogeodynamica Baltica: Brandenburgische Geowissenschaftliche Beiträge, v. 2. 59-67. Gelumbauskaitė Ž. 1982. Methods and results of the study of the deformations of ancient shore levels of the South-Eastern part in the Baltic Sea. Baltica 7. 95-107. Gelumbauskaitė L Ž. 2000. Late- and Postglacial palaeogeomorphology on the Klaipeda Submarine slope, southeastern Baltic Sea. Baltica. 13. 36-43. Vilnius. Gelumbauskaitė L Ž. 2002. Holocene history on the northern part of the Kuršiu Marios (Curonian) Lagoon. Baltica 15. 3-12. Gelumbauskaitė, L. Ž., Šečkus, J. 2005a. Late Quaternary shore formations of the Baltic basins in the Lithuanian sector. Geologija, 52: 34-45.
Gelumbauskaitė, L.Ž., Šečkus, J. 2005b. Late-Glacial Holocene history in Curonian Lagoon (Lithuanian sector). Baltica, 18(2): 77-82. Gudelis, V. 1961. Neotectonic movements in eastern Baltic. Materials of Quaternary geology commission. [in Russian] Harff, J., Frischbutter, A., Lampe, R., Meyer, M. 2001. Sea-level change in the Baltic Sea: Interrelation of climatic and geological processes. In Gerhard, L. C., Harrison, W. E., Hanson, B. M. (eds.) Geological perspectives of global climate change. 231-250. Jarmalavičius, D., Žilinskas, G., Kulvičienė, G. 2001. Peculiarities of long term water level fluctuations on the Lithuanian coast. Acta Zoologica Lituanica No. 11(2). 132-140. Kabailienė M. 1997. Shore line displacement, palaeoecological conditions and human impact on the south-eastern coast of the Baltic Sea. In: A. Grigelis (ed.). The Fifth Marine Geological Conference. Abstracts: 114-122. Vilnius. Lukoševičius, L. Gudelis, V. 1974. The subaqueous Late- and Post-Glacial shorelines in the South-eastern area of the Baltic Sea. Baltica 5. 113-118. Mörner N.-A. 1980. Late Quaternary sea-level changes in north-western Europe; a Synthesis. Geologiska Foreningens I Stockholm Forhandlingar. 100. 381-400. Pustelnikovas, 1996. Climatic change and sedimentation in the Curonian (Kuršių Marios) Lagoon during the last 300 years. The Geographical Yearbook, XXIX. 279-288. [in Lithuanian]
13000 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 Calendar years, BP 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 Radiocarbon years, BP.. Allerod Younger Dryas Baltic Ice Lake Pre- Boreal Yoldia Boreal Ancylus Atlantic Litorina Sub- Boreal Postlitorina Sub-Atlantic Chronozone Baltic Sea stage +10 +5 0-5 -10-15 -20-25 Relative sea level changes; compiled by L. Ž. Gelumbauskaitė, 2005 Relative sea level changes after Kabailienė, 1 997 Relative sea level changes after Bitinas et al., 2004-30 -35-40 -45-50 Fig. 5. Shoreline displacement curves in the south-eastern Baltic according to different authors (Gelumbauskaitė et al. 2005a). -55-60 12000 13000 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 11000 Allerod.. Youn ger Dryas Baltic Ic e Lake 10000 Pr e- Boreal Yoldia 9000 Boreal Ancylu s 8000 7000 6000 Atlantic L it orina 5000 4000 3000 Sub- Bore al 2000 Postlitorina 1000 Sub -Atlantic Calendar years, BP Radiocarbon years, BP Chronozone Baltic Sea stage +10 +5 0-5 -10-15 -20-25 -30-35 -40 Relative sea level changes in the south-eastern Baltic area (after L. Ž. Gelumbauskaitė, 2005) Eustatic sea level changes in th e Atlantic-Caribbean region (after Fairbanks, 1989 ) Eustatic sea level changes (after Fairbridge, 1961) Eustatic sea level changes in the southern Scandinavia.. (after Morner, 1980 ) -45-50 -55-60 -65-70 -75-80 -85-90 Fig. 6. Comparison of relative sea level changes in the south-eastern Baltic and eustatic changes in the North-West Europe and Atlantic-Caribbean region.
H, cm 25 20 15 10 5 0 800 750 700 650 600 550 3 Q, m /s -5 500-10 450-15 400-20 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 350 Years Klaipėda Nida Smalininkai Fig. 7. Short term fluctuations in the mean water leveli n the Baltic Sea (at Klaipėda) and Curonian Lagoon (at Nida) and those in the Nemunas river runoff (at Smalininkai) (Jarmalavičius et al. 2001).