engleski

Croatian caves as a study sites for the reconstruction of the Quaternary environments

Although relatively small in surface, Croatia appears to be well-suited for the Quaternary environmental reconstructions from several different aspects. It is located on the crossroad of continental European and maritime Mediterranean influences that varied and shifted along with Quaternary climate changes. Besides, almost half of its continental territory and vast submarine part is karstic, with probably more than 10000 known caves. Speleothem-based studies have already been conducted in dozens of them revealing the Quaternary history with more or less success. At first glance, continental (subaerial) caves generally offer good potential due to accessibility throughout the year, distributions over a relatively restricted area but within different altitudes and climate settings, abundance of speleothems etc., but during the cave monitoring and laboratory work numerous obstacles emerged – from the meteorological, biological and technical hindrances at the research sites to the 14C and U-Th dating issues. Nevertheless, certain progress of the palaeoenvironmental reconstruction from MIS 10 to the Recent is evident. Valuable environmental records have also been archived in thousands of years old ice accumulated in several ice-caves located in the highest Croatian regions. Submerged (submarine) caves, with present number of more than 230 discovered along the eastern Adriatic coast, offer an additional Quaternary story related to the sea-level changes. Their occurrence bellow the sea surface is already irrefutable evidence of former lower sea-level stands, as well as speleothems within them. Moreover, in ideal situation, speleothems with their interrupted growth and alteration of spelean and marine deposits can record sea-level fluctuations. In spite of numerous setbacks caused by boring marine organisms, high initial Th and/or low U concentration, Late Pleistocene– Holocene relative sea-level changes along the Croatian coast has been partially reconstructed. Sea-level oscillation which can be attributed to MIS 5a interstadial that was marked with two distinct sea-level highstands (double peak) was one of the best resolved. Additional challenges for palaeoenvironmental reconstruction are common in submerged features that are in-between aforementioned continental and submarine end members, namely in i) submerged springs (vruljas) which once were caves, then coastal springs and presently have hydrological function as submerged fresh- or brackish water spring and ii) coastal anchialine caves which also host fresh, brackish and sea water habitats. Both types are relatively common (>150) along the Croatian coast and are subject of multidisciplinary researches.

Caves, palaeoenvironmental reconstruction, Quaternary, Croatia

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