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The purpose of this thesis is to reconstruct the paleoclimate record of the past climatic conditions during the Holocene.

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Academic year: 2021

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ABSTRACT Chiara Nocchi

ABSTRACT

The purpose of this thesis is to reconstruct the paleoclimate record of the past climatic conditions during the Holocene.

To obtain this, the analyses of three stalagmites, from the Corchia Cave, were conducted. This Cave, located in the south-western part of the Alpi Apuane (NW Tuscany, Italy), is the most important Italian karst system: its extension reaches about 60 km of cave passages.

The analyzed stalagmites are only a small part of the available material, because this cave kindles interest in researches, also due to the large amount of uranium in the concretions that allows to date very well these.

The stalagmites, CC53, CC4 and CC27, were collected in the so-called "Galleria delle Stalattiti", a phreatic conduit in the Corchia Cave, placed ca. 870 m a.s.l.

The stable isotopes analyses were conducted in the Laboratories of the Geology Faculty of the University of Newcastle and U/Th dating at the School of Hearth Sciences, to the University of Melbourne.

The GV2003 mass spectrometer was used to perform stable isotopes analyses (oxygen and carbon). With this date, a preliminary curves were construct, and from this is possible to recognize positive and negative peaks, respectively related to colder and warmer period.

Later, the age determinations were conducted, using a spectrometer MC-ICPMS for the application of the U-Th method. Preliminary age models were then obtained and stable isotopes records were transformed in time series.

The stalagmite CC53 shows a period of growth between ca. 6000 and 400 years, corresponding to the second part of the Holocene. In the oxygen and carbon trends it was possible to observe the last part of the "Hypsithermal" and the next period, called "Neoglacial", marked by an increase in the oxygen isotopic composition.

During this cold period there are several minor phases, but the most evident is the

so-called "Medieval Warm Period", ca. between 1000 and 850 years ago, where

the values are very negative. Although the age model of the second stalagmite

(CC4) is not as good as the CC53, general trends are comparable, supporting the

genuine climatic signal embedded in these two stalagmites.

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