Sedimentary and neotectonic history of Lake Ohrid (Macedonia/Albania): acquisition and interpretation of new geophysical and geological data
Final Report Abstract
Transboundary Lake Ohrid between Albania and Macedonia is considered to be the oldest continuously existing lake in Europe; age estimates range from 1-10 Ma. An extraordinary high degree of endemism, including more than 210 described endemic species, makes the lake a unique aquatic ecosystem of worldwide importance. This project aimed in collecting pre-site survey data for a deep drilling campaign at Lake Ohrid. On-and offshore data were used to reconstruct the sedimentary and tectonic evolution of the lake. Three main phases of deformation can be reconstructed based on structural and paleostress analyses: NW-SE shortening (folding and thrusting phase is related to Alpine nappe emplacement), NE-SW shortening (the change of the stress field in Late Miocene/Quaternary times, later folding and thrusting phase and strike-slip movements) and, a present-day E-W extension with N-S trending normal faults. The northern and southern plains of Lake Ohrid are dominated by fluvial clastic input, while the eastern and western shores are controlled by active normal faulting. The offshore data show an up to 700 m-thick sedimentary succession in the central Ohrid basin. The sedimentary fill overlying the basement is interpreted as fluvial and/or alluvial deposits in an early stage of extension after initiation of the basin or after a new fault got active and formed a sub-basin in shallower water depth. The majority of the sedimentary infill in the central basin is deciphered as deep water lacustrine deposits representing the syn-rift stage of Lake Ohrid after the basin was filled with water. Reflectors flatten towards younger strata, which is an indicator for a decrease in subsidence. The absence of shallow water seismic facies suggest that the basin is still in an underfilled stage implying that extension is still ongoing. A first seismic chronological model suggest an age between 1.5 and 2 Ma for Lake Ohrid. Several clinoform structures have been identified within the lake indicating major lake level fluctuations since its existence as water filled body. Five primary drill sites were selected for ICDP-drilling based on the seismic data. The most important site (DEEP) is located in the central part of the Lake Ohrid basin at a water depth of 250 m and will provide substantial information on the age and origin of the lake. Four drill sites closer to the shore of the lake will provide information on major changes of the hydrological regime, the age of ancient foresets, tectonic activity, and mass movements.
Publications
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2009. Scientific Collaboration on Past Speciation Conditions in Lake Ohrid–SCOPSCO Workshop Report. Scientific Drilling, 7, 51-53
Wagner, B, Wilke, T, Krastel, S, Grazhdani, A, Reicherter, K, Trajanovski, S., Zanchetta, G.
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(2010) Stratigraphic analysis of Lake Level Fluctuations in Lake Ohrid: An integration of high resolution hydro-acoustic data and sediment cores. Biogeosciences, 7, 3531–3548
Lindhorst, K., Vogel, H., Krastel, S., Wagner, B., Hilgers, A., Zander, A., Schwenk, T., Wessels, M., Daut, G.
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(2010). Evolution of ancient Lake Ohrid: a tectonic perspective." Biogeosciences, 7, 3377–3386
Hoffmann, N., Reicherter, K., et al.
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SCOPSCO Working Group, 2010. Sedimentary and tectonic evolution of ancient Lake Ohrid (Macedonia/Albania). Mitteilungen der Deutschen Geophysikalischen Gesellschaft, 1-2010, 28-31
Lindhorst, K., Krastel, S., Wagner, B.
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(2011) Active basins and neotectonics: the Lake Ohrid (FYROM, Albania), ZDGG, Tectonics and Sedimentation, 162, 217-234
Reicherter, K., Hoffmann, N., Lindhorst, K., Krastel, S., Fernández-Steeger, T.
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(2012) Mass wasting in Lake Ohrid (FYR Macedonia/Albania) – hydroacoustic analysis and its tsunamigenic potential. Submarine mass movements and their consequences. Advances in Natural and Technological Hazards Research, 31, Springer, 245-253
Lindhorst, K., Grün, M., Krastel, S., Schwenk, T.
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(2012) Quaternary coastline evolution of Lake Ohrid (Macedonia/Albania). Central European Journal of Geosciences, 4(1), 94-110
Hoffmann, N., Reicherter, K., Grützner, C., Hürtgen, J., Rudersdorf, A., Viehberg, F.A., Wessels, M.
