engleski

Holocene environmental records from Croatian speleothems

Several speleothem studies from Croatian karst caves proved to be valuable archives of local to regional palaeoenvironmental changes on various time scales. Variations of oxygen and carbon stable isotope ratios (δ18O and δ13C) from eight stalagmites recovered from six caves demonstrated diverse responses to hydroclimate changes throughout the Holocene. The main reason for this diversity stems from their geographical distribution and specific locations: Nova Grgosova Cave (239 m a.s.l.) is in the continental part of Croatia, mid-Adriatic region is represented by the coastal Modrič Cave (32 m a.s.l.), mountainous Manita peć Cave (570 m a.s.l.) and Strašna peć Cave (74 m a.s.l.) on the island of Dugi otok, while the records from the southernmost part of Croatia are kept in Mala špilja (60 m a.s.l.) and Velika špilja (90 m a.s.l.) caves on Mljet Island. According to the long term continuous or periodical monitoring of cave environmental settings and in accordance with other regional records, spelean carbonate δ13C is interpreted as a proxy for spring/summer environmental conditions. It is proposed that this proxy mainly reflects bioproductivity (i.e. microbial activity and vegetation density) which is at its highest in spring and summer. δ18O is interpreted as a proxy for autumn/winter conditions held to be linked to the rainfall amount variability. Starting from possible record of Younger Dryas, signals of some major hydroclimate events are more (e.g. 4.2 ka) or less (e.g. 8.2 ka) pronounced when compared to some other European records. Within Holocene Climate Optimum, around 7.4 ka, continental region experienced sudden drought, which is not clearly expressed in speleothem records from South Croatian coastal region. Additionally, human intervention into the natural landscape left anthropogenic signal, sometimes hiding or modifying the latest short-term (centennial) climatic variability throughout the last millennium.

speleothems, stable isotopes, hydroclimate, Holocene, Croatia

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