La geochimica degli isotopi stabili applicata a reperti scheletrici fossili per ricostruzioni paleoambientali (sito archeologico di Arslantepe –Turchia).

The archaeological site of Arslantepe (Malatya, Turkey) represents a very interesting case-study for investigating the relationship between climate change and civilization’s history: the site, almost continuously populated over a long time (6250-2700 cal yr. BP), has given a great amount of skeletal remains which are distributed on a fairly well-resolved archaeological stratigraphy also improved by radiocarbon dating; these remains, studied trough the techniques of stable isotope geochemistry can provide paleoclimatic proxy data. In this work we studied the stable isotope composition of 507 samples of human and animal skeletal remains (mainly sheep, goat, cattle). The measured isotope ratios are referred to oxygen (δ18Ocarb, δ18Oph), carbon (δ13Ccarb, δ13Ccoll) and nitrogen (δ15N); they were studied in the mineral and organic fractions of bone tissue; the variability in time of these parameters, mainly related to paleonutrition, can be correlated, directly or indirectly, to changes in environmental parameters such as atmospheric temperature and moisture. Results show that wild and domestic animal diet in Arslantepe was almost exclusively composed of plants exploiting the C3 photosynthetic pathway, which are typical of wet or temperate climates. The presence of C4 plants (typical of dryer climates) could be found only in cattle diet (Bos taurus). Human diet was based mainly on terrestrial food, and in particular cereals, caprine meat and little or any pig and cattle meat. From the paleoclimatic point of view, the most important result of this work is the identification of the preservation of a long-term paleoclimatic signal in δ18OW calculated values (oxygen isotopic composition of ingested liquid water), that identifies conditions of maximum moisture at 5000 BP; these data are well correlated (in terms of trend and amplitude) to the oxygen isotope stratigraphy of lacustrine sediments found in zone near the study area. Two aridification events, representing short-term climate anomalies punctuating the above general trends, were recognized through the comparison of the studied isotope parameters. Also these episodes apparently correlate to dramatic regional-scale episodes documented in former literature.