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Eastern Adriatic paleoenvironmental changes recorded from MIS 10 to the Recent in the Modrič Cave (Croatia) speleothems – preliminary report

The eastern Adriatic region is influenced both by Atlantic and Mediterranean air masses whose predominance might have changed during the late Quaternary along with global climate changes. Evidences of those shifts are expected to be archived in speleothems within numerous Croatian caves. One of such is Modrič Cave located 120 m from the shoreline at the foothill (32 m a.s.l.) of the coastal Velebit Mountain. Monitoring of principal hydroclimate characteristics (surface and cave temperature and relative humidity, rain and dripwater intensities, and stable isotope composition of the precipitation and cave water) pointed to the very stable environment appropriate for the carbonate precipitation in isotopic equilibrium with related dripwater, thus suitable for the paleoclimate reconstruction. Three speleothems collected from the deep interior covered time span from MIS 10 to the Recent, i.e. periods 340-4.6 ka, 66.4-0.8 ka and 197-3.2 ka. High- resolution stable isotope analyses preformed on the overlapping oldest and youngest stalagmites showed relatively large oscillations of d13C values (from -13.11‰ to -4.89‰ and from 12.22‰ to -1.00‰, respectively) and of d18O (from -8.16‰ to -3.08‰ and from 6.94‰ to -2.97‰, respectively), but with weak correlations to carbonate fabrics. Upon the completed detailed analyses, this time series will be the longest speleothem-based paleoenvironmental record on the eastern Adriatic coast, comparable with adjacent existing records. This research is a part of the project 1623 Reconstruction of the Quaternary environment in Croatia using isotope methods - REQUENCRIM financed by the Croatian Science Foundation.

Speleothem, cave, palaeoenvironment, Modrič Cave, Croatia

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