engleski

Palaeoenvironmental records from ice caves of Velebit mountains - Ledena pit and Vukušić ice cave, Croatia

Perennial ice is a common deposit in the caves of north Velebit Mts. On the basis of historical cave maps ice level subsidence were estimated to 9 m and 0.2 m between 1962 and 2007 in Ledena Pit and Vukušić Ice Cave, respectively. The ice loss trend in Ledena Pit has seemed to slow down since the mid-1990s. Reassessment of the 1995-year tritium measurement suggests that the ice formed from the precipitation of the ’ 63-bomb-peak might be at 3.75 m below the 1995 ice surface. Mean ice accumulation (racc) and basal melting (rbm) rates were calculated for the 1963-1995 period as 18 cm/yr and 38 cm/yr, respectively. The lowermost ice layer (-40 m) can be dated to 333 year-old applying racc or 105 year-old by rbm. The large difference can be interpreted as racc is probably valid only for the upper few metres of the deposit, while the long-term mean accumulation rate is better approximated by the rbm. Comparison of stable isotopic composition of nine cave ice samples and the local precipitation suggests that the precipitation of the winter half year exerts major role in the ice formation overriding the importance of the rain from summer half year.

ice loss; basal melting; tritium; stable oxygen isotopes; stable hydrogen isotopes

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