Sedimentary and neotectonic history of Lake Ohrid (Macedonia/Albania): acquisition and interpretation of new geophysical and geological data

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Lake Ohrid at the Macedonian/Albanian border is one of the oldest lakes in Europe and was tectonically formed probably during the Tertiary. Lake Ohrid houses large concentrations of endemic taxa and represents a first class site to investigate the link between geological and biological evolution in lakes. Lake Ohrid was included as a target area of ICDP already in 1993 but appropriate site survey data were lacking. In the first phase of the project detailed on- and offshore investigations were carried out in order to reveal the Neogene depositional and tectonic history of Lake Ohrid and to evaluate the potential for deep drilling. The new seismic data show numerous sedimentary features such as terraces, clinoforms, mass movement deposits and areas of extensive faulting, but also a deep central basin with undisturbed sediments. Sediment thickness on top of the basement is up to almost 700m. Based on the acoustic data, five primary sites were chosen as potential drilling targets. The onshore work concentrated on detailed paleostress analyses including morphotectonics, which lead to a preliminary stress history with three individual phases. The results of the first project phase are essential parts of drilling proposal ‘Scientific Collaboration On Past Speciation Conditions in Lake Ohrid (SCOPSCO), which was submitted to ICDP in January 2009. Planned work in this prolongation proposal mainly aims in i) studying the depositional history of Lake Ohrid, reflecting environmental changes, and ii) performing detailed structural and fault analyses of Lake Ohrid and its surrounding.