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Submerged speleothems as archives of sea level changes on Croatian Adriatic coast

Croatian Adriatic coast is typical ingressional karstic coast rich in various sea-level indicators eligible for the sea-level changes reconstruction. However, its position in tectonically active region i.e. on Adria (Apulian) microplate (located between converging African and Eurasian plates), makes it unsuitable for the eustatic sea-level reconstruction. Therefore, global sea-level curve, together with the related glacio-hydro-isostatic models, is used in order to reconstruct relative sea-level changes and regional/local tectonics. So far, more than 235 submerged caves were discovered along the Croatian coast and islands, and comparing to the situation on the mainland, probably thousands of them are yet to be found below the sea level. More than 140 explored caves contain speleothems – typical subaerial features, formed during the low sea stands. Alteration of depositional and non-depositional phases within speleothems can offer an insight into sea-level fluctuation. Until now, 18 speleothems were examined from 4 caves, 4 pits and 1 submerged spring, collected from the depths of -1.5 m to -53 m. Radiometric (U-Th, 14C) dating obtained ages from ~310 ka to 3, 3 ka BP (Nita et al., 2012 ; Surić et al., 2009, 2010 ; Surić & Juračić, 2010). A pair of stalagmites from Krk Island provided the most detailed signal of MIS 5.1 sea-level fluctuations pointing to possible episodic uplift of that region. Lately, researches are focused to the deepest and the oldest finding – stalagmite from -53 m from Šolta Island which covers MIS 9.1, and to shallow (-4 m) and relatively young (~7 ka) stalagmite from Dubrovnik area which should apparently resolve the most recent submersion history. References D. Nita, D. Richards, M. Surić, J. De Waele, 2012. MC-ICPMS U-Th age determinations on altered submerged speleothems from Croatia, NSF Workshop "Sea-level Changes into MIS 5: from observations to prediction", 10-14 April 2012, Palma de Mallorca, Spain M. Surić, D.A. Richards, D.L. Hoffmann, D. Tibljaš, M. Juračić, 2009. Sea-level change during MIS 5a based on submerged speleothems from the eastern Adriatic Sea (Croatia), Marine Geology, 262, 62-67. M. Surić, R. Lončarić, N. Lončar, 2010. Submerged caves of Croatia – distribution, classification and origin, Environmental Earth Sciences, 61/7, 1473-1480. M. Surić, M. Juračić, 2010. Late Pleistocene – Holocene environmental changes – records from submerged speleothems along the Eastern Adriatic coast (Croatia), Geologia Croatica, 63, 2, 155-169

Submerged speleothems; sea level changes; Croatia; Adriatic sea

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