Pliocene–Early Pleistocene climatic trends in the Italian Peninsula based on stable oxygen and carbon isotope compositions of rhinoceros and gomphothere tooth enamel

Abstract

Abstract The Pliocene and Early Pleistocene (5.2–1 Ma) palaeoclimate for localities in Italy is evaluated using stable carbon and oxygen isotope compositions of tooth enamel of fossil specimens from Rhinocerotidae ( Stephanorhinus sp.) and Gomphotheriidae ( Anancus sp.) taxa. Carbon isotope composition was measured in the structural carbonate (δ 13 C), while oxygen isotope values were determined both in the structural carbonate (δ 18 O CO3 ) and the phosphate (δ 18 O PO4 ) of bioapatite. The δ 13 C CO3 values indicate that the taxa were grazers-browsers of a pure C 3 vegetation. Low δ 13 C CO3 values for Central and North Italy indicate a humid climate with woodlands and forest cover in the Pliocene. For northern localities the δ 13 C values increase between MN16a and MNQ16b biozones most likely linked to the Northern Hemisphere Glaciation at 2.7 Ma after the “Mid-Pliocene Warm Period”. For Central Italy the values have a wide range with a long term increasing trend in the Early Pleistocene, indicating more arid climate and/or more open vegetation. Overall, the δ 18 O PO4 values in Central Italy change together with the δ 13 C CO3 values and are taken to reflect the warmer/wetter interglacials and cooler/more arid glacial phases. The δ 18 O PO4 values in North Italy are lower than those in Central Italy and show no clear temporal trend. One explanation for the low values especially in MN14-15 biozone is that these δ 18 O PO4 values do not reflect entirely the isotopic composition of local precipitation but river waters from the Alps with 18 O-depleted isotopic compositions or a N-S directed rain-shadow effect on the precipitation. In general the new isotope data agree well with palaeoclimate reconstructions based on palynological and other proxies.