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MC-ICPMS U-Th age determinations on altered submerged speleothems from Croatia

We have attempted to date two deep submerged speleothems (POG-1, -53.0 m ; POG-2, -35.6 m) from a coastal cave near Šolta, Croatia, to supplement the previous work from this coast (Surić et al., 2005, 2009). Both samples are heavily encrusted with marine overgrowths and were sampled in situ. POG-2 has a few large (>1.5 cm diameter) lithophagus holes without shells and has a mono-crystalline calcite core. We suspected it might have an open-system U-Th signature and this has been confirmed by recent results. However, POG-1is composed of dense macro- crystalline calcite with well-preserved growth layers. While numerous MC-ICPMS U-Th determinations indicate that there are finite ages of ~ 310 ka at the top and base of the sample and potentially very rapid growth, there are also sections that altered and indicate stratigraphic reversals, making interpretation difficult. Acknowledgements: Our thanks to the cave divers Markus Schafheutle and Michael Kühn for samples and underwater photographs. References Surić, M, Richards, D.A., Hoffmann, D.L., Tibljaš D., Juračić, M. 2009.Sea level change during MIS 5a based on submerged speleothems from the eastern Adriatic Sea (Croatia). Marine Geology, 262: 62- 67. Surić, M, Juračić, M., Horvatinčić, N. Krajcar Bronić, I.( 2005): Late Pleistocene-Holocene sea- level rise and the pattern of coastal karst inundation: records from submerged speleothems along the Eastern Adriatic Coast (Croatia). Marine Geology, 214: 163-175.

submerged speleothems; U-Th dating; Adriatic Sea; Croatia

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