PALEOCLIMATOLOGICAL RECONSTRUCTION USING STABLE-ISOTOPE DATA ON CONTINENTAL MOLLUSKS FROM VALLE-DI-CASTIGLIONE, ROMA, ITALY

Thirty molluscan shells from twenty levels from the first 4.5 m of a l ong core drilled in the crater lake of Valle di Castiglione, near Rome , have been analysed for their oxygen and carbon stable isotope compos itions. The investigated portion of the core covers the last 14.2 ka B P. The large range in delta(18)O (11 parts per thousand) suggests that hydrological conditions exercise the main control on the isotopic com position of the biogenic carbonate in the Valle di Castiglione palaeol ake. Samples younger than about 5 ka show a marked O-18 depletion, whi ch we attribute to the onset of a temperate wet climate, corresponding to the maximum of humidity. Isotopic results are in good agreement wi th pollen analyses and prove to be a sensitive tool for reconstructing Quaternary climatic evolution from the continental lacustrine sedimen ts of Central Italy.