Role of a labile terpene compound in the assessment of the age of a fossilwood from Siena (Tuscany, Italy)

Fossil samples of Pinus sylvestris is found near Siena (Tuscany, Italy) in geological formations 2-3 million years old were chemically examined in ord er to solve the problem of the contrast between the age of Ecological forma tions and their good degree of preservation. Comparison with a living Pinus sylvestris was carried out on standard wood component analyses, cation exchange capacity and residual terpene content. The analyses of wood components were close to those of the reference pine, whilst the cation exchange capacity values showed remarkable changes. The i ncrease of salt carboxyls suggested the hydrolysis of ester carboxyls origi nally present, whilst the reduction of total carboxyls revealed a partial l oss of hemicelluloses. Both changes were attributed to the percolation of s alt-bearing water through the wood, thus causing ester hydrolysis, carboxyl salification and hemicellulose solubilisation. Residual terpene analysis s howed, for the first time in a terrestrial fossil, tetrahydroabietic acid w hich forms by disproportion of the abietic acid. The C-14 dating assigned t he fossil tu an age of about 18,000 years and suggested a landslide of Wurm ian interglacial age occurred inside the geological formations of 2-3 milli on years old. Transient terpene compounds, formed in incipient diagenesis, are proposed a s tracers for the assessment of particular ranges of fossil age, as previou sly suggested by the analyses of both a Larix decidua 14,500 years old and a Picea abies 100,000 years old.