Determining the Source for the Magmas of Monte Amiata (Central Italy) Using Strontium, Neodymium, and Lead Isotope Analysis

Monte Amiata is a recently extinct volcano that produced trachydacites and a few small olivine latite flows. The Amiata suite showed crustal strontium, neodymium, and lead isotopic signatures. Sr/Sr ratio values ranged from 0.712447 to 0.713068 and Nd/Nd ratios ranged from 0.512094 to 0.512203. Pb/Pb values ranged from 15.6694 to 16.2330 and Pb/Pb ratios ranged from 18.7125 to 19.0882. The olivine latite flows towards the end of volcanic activity would suggest more mantle influence than the data suggests, but Amiata may be sourcing from a depleted mantle as well as the limestone that proliferates throughout Italy. Strontium concentrations are similar to those of rubidium, so neodymium-samarium comparisons were utilized, as they are more reliable. Neodymium concentrations, when placed against samarium concentrations, indicate crustal contamination, as do the isotope data.