engleski

HOLOCENE PALEOENVIRONMENTAL RECONSTRUCTION OF A KARST KRKA RIVER ESTUARY (EASTERN ADRIATIC COAST)

The Krka River Estuary is a microtidal karstic salt-wedge estuary located in the central Dalmatia (Croatia). The upper part of the estuary, i.e. the submerged narrow canyon and the Prokljan Lake, was studied for the first time by multiproxy analyses of 5 sediment cores supplemented with bathymetric and high-resolution seismic data. The aim was to identify the main processes controlling the sedimentary infill and to reconstruct its paleoenvironmental evolution during the Holocene. The study revealed a unique and well preserved submerged paleolandscape with an evolution from lowstand fluvial and lacustrine environment to transgressive and highstand estuarine to marine conditions. Seismic data showed a Pleistocene fluvial incised Krka River valley, with low accumulation rates and sediment bypass towards the Adriatic shelf. At the beginning of the postglacial transgression, a favorable conditions were established for the growth of tufa deposits in the form of barriers with waterfalls. Erosional power of the river was low during this period and fluvial to lacustrine sediments started to accumulate. With further sea level rise, at approx. 10000 y BP, the sea started to inundate the Prokljan Lake. This led to the cessation of tufa growth and the deposition of the estuarine muds with the establishment of the fully estuarine/marine salt-wedge conditions during the highstand (approx. 7500-7000 y BP). Our study revealed a very dynamic paleoenvironmental evolution of the estuary controlled by a rapid sea level rise, local geomorphology and hydrodynamics.

salt-wedge karstic estuary ; sea level ; submerged landscape ; seismic stratigraphy ; Eastern Adriatic Coast ; Holocene

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