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Coastal karst forms and dating of sea flooding. Data from the Eastern Adriatic coast (Croatia)

Eastern Adriatic coast (reffered in geomorphological literature as the classical Dalmatian type coast, Von Richthofen, 1886 ; in Fairbridge, 1968) borders the classical karst region of the Dinarics. There, in up to 8000m thick Mesozoic carbonates all karst forms are developed. Along the coast, at the land/sea interface and below the sea surface some peculiar features are developed. They include karstic estuaries (Sondi et al., 1995), marine lakes (isolated marine water bodies) (Ćosović et al., 2002), drowned canyons, and submarine caves and pits, some of them with speleothems (Surić et al., 2002) . Most of the forms are of subaeral origin and are only submerged by sealevel rise. However, accumulation forms (marine biogenic overgrowth, marine sediments) can help in dating of the Late Pleistocene – Holocene sea-level changes. Few speleothems were collected from three submerged speleological objects along the Croatian coast at depths from 38.5 m to 17 m below present sea level. The marine biogenic overgrowth layer, the youngest and the oldest part of the speleothems were dated by the 14C method, and their stable isotope (13C and 18O) content was measured. From the measured 14C activity of the marine overgrowth the start of overgrowth, i.e. the time of flooding by sea water, was determined (9.1 ka ago at -36 m and 7.1 ka ago at -23 m). The obtained results generally fit into the sea-level curves reconstructed for adjacent areas (Tyrrhenian Coast and French Mediterranean Coast). Ćosović, V., Juračić M., Bajraktarević, Z., & Vaniček, V. (2002): Benthic foraminifers of the Mljet Lakes - potential for (paleo)environmental interpretation. Mem. Soc. Geol. Italiana, 57, 533-541 Fairbridge, R. W. (ed) 1968): The encyclopedia of Geomorphology, Reinhold Book Corp. New York, 325-329. Sondi, I., Juračić, M & Pravdić, V. (1995): Sedimentation in a disequilibrium river-dominated estuary. The Raša River Estuary (Adriatic Sea-Croatia). Sedimentology, 42, 769-782. Surić, M., Juračić, M., & Horvatinčić, N. (2002): Late Pleistocene - Holocene changes of the eastern Adriatic coast line. In: F. Veloso-Gomes, F. Taveira-Pinto, & Luciana das Neves (eds.) Littoral 2002. The Changing Coast. Eurocoast/EUCC (Proceedings of the 6th int. symposium Porto, 22-26 September 2002, Vol III), Eurocoast-Portugal association 259-263.

Late Pleistocene - Holocene; submerged speleothems; 14C dating; karst; Adriatic Sea

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