Nadine Hoffmann

Tectonic Evolution of the Lake Ohrid Basin (Macedonia / Albania) Nadine Hoffmann

Lake Ohrid is situated in an active tectonic region at the border between the Former Yugoslavian Republic of Macedonia and the Republic of Albania. This UNESCO World Heritage site is an ancient lake with an age of 2 - 5 Ma and among the oldest lakes in Europe. Lake Ohrid has more than 200 endemic species making it the lake with the highest concentration of endemic diversity in the world when considering its small surface area of 358 km$^2$. Several phases of deformation have affected the area since the Tertiary due to the influence of the Northern Hellenic Trench. This activity is documented by frequent moderate and a few major earthquakes, which have formed a seismic landscape. It therefore represents a first class site to investigate the impact of geological, climatic, and environmental events on biological evolution within lakes. This thesis is focused on the tectonic framework and geomorphological evolution of the basin. Palaeostress and structural analyses were undertaken to determine the past and recent tectonic stress regimes; this provides data on the current deformational system gives and provides insights into the morphological development. Results from detailed sedimentary analyses allow several coastal domains and sedimentary realms to be distinguished. This also provides information on how the lake responds to landscape change and how the lake level varied during the Holocene. A detailed geomorphological study deals with the expression and geometrical properties of fault scarps including the analysis of scarp lengths, their spatial distribution and a survey on how lithology interacts with scarp formation in the area. This gives insights into localised basin activity. Finally, the question as to whether seismic activity, together with the geological character of Lake Ohrid, is capable of triggering speciation events in the lake is answered.