Changes in Holocene Precipitation Pattern of the Central Mediterranean Inferred from Hypogean Tufa Proxy Data

This paper deals with proxies preserved in hypogean tufas of a highly responsive region to climate changes, the central Mediterranean. Field studies allowed determining four stages of carbonate accretion driven by climatic and / or environmental shifts over the mid-late Holocene (i.e., the last eight millennia). The studied accretions show petrological analogies with the so called "trays", particular speleothems reported in few worldwide caves. Positive covariation between the ratios of oxygen and carbon isotopes is interpreted as due to climate signal. Hypogean tufas have recorded a long term (probably millennial-scale) reduction in precipitation and / or shift in storm trajectories as the interlacement of geological and geochemistry features suggests. Local conditions likely became severely dry over the transition from middle to late Holocene. Comparison between tufa archives and regional-scale data may improve climate knowledges and calibration of models. Further researches need interdisciplinary approaches to solve some basic uncertainties and to enhance data on geological archives.