engleski

Plitvice Lakes – a hydrogeologic phenomenon

In the presentation an explanation for the existence of freshwater Plitvice Lakes in Dinaric karst will be presented. Formerly the existence of the Plitvice lakes was considered a “miracle” due to the fact that generally in the high karst region underground water flow prevails. The area where Plitvice Lakes are located is built of carbonate rocks of Mesozoic age. There is a thick series of dolomite and limestone rocks (3500 – 4000 m) that were deposited from Upper Triassic (T3 “Hauptdolomit”) to Upper Cretaceous (K2 rudist limestone and marly (clayey) limestone). In the upper part (below Upper Lakes) this Triassic dolomite covers older impermeable clastic rocks, and the formation of surface flow is easily explained. However, the Lower Lakes are formed in Upper Cretaceous well karstified limestone with a number of caves in the canyon flanks. The only plausible explanation is that a series of marly (clayey) limestone of Turonian age (K22) represents a barrier for underground flow. Therefore, the litholology could explain the existence of the surface water flow. The existence of the lakes is, however, the consequence of intense deposition of calc tufa within the water flow. Mechanisms, chemistry and biogeochemistry of calc tufa deposition are important topic of the ongoing research in the world.

karst; freshwater lakes

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