Molybdenum Isotopes of the Subduction-related Orogenic Potassic Magmas of Central-Southern Italy

The potassic and ultrapotassic magmas of the Tuscan Magmatic Province and Mt. Vesuvius represent two well characterised subduction-related magmatic associations along the Tyrrhenian border of the Italian peninsula. They display exotic and distinctive geochemical and radiogenic isotope features, which were traditionally related to differences in the lithology of the subducted material in their respective mantle sources. Their Mo content, when correlated to an other trace element with similar degree of incompatibility such as Ce, displays significant differences in terms of Ce/Mo values (ca. 25 for Vesuvius and ca. 340 for Tuscan magmas). However, the two magmatic suites show surprisingly similar δ98/95Mo values (0.10 - 0.26 ‰ for Vesuvius and 0.07 – 0.22 ‰ for Tuscan Magmatic Province), which are significantly heavier than typical mid-ocean ridge basalts. While the δ98/95Mo values implicate an isotopically heavy sedimentary component recycled into their respective mantle sources, the different Ce/Mo ratios reflect contrasting elemental fractionation during sediment melting related to the lithology and consequent residual mineralogy of the subducted sedimentary material undergoing melting. This dataset presents Mo, δ98/95Mo, and trace element analysis measured by ICP-MS and Sr and Nd ratios measured by TIMS in orogenic potassic magmas and sedimentary end-members from Central-Southern Italy.