The Mercury Isotopic Composition of Earth's Mantle and the Use of Mass Independently Fractionated Hg to Test for Recycled Crust

Mercury isotopes were measured in a suite of well-characterized (for Sr-Nd-Pb-Hf isotopes) ocean island basalts from Tubuai, Pitcairn, Samoa, and Iceland. Lavas from the Afar hotspot were also examined. The data show that ocean island basalts exhibit both mass-dependent fractionation of Hg isotopes. Critically, the data reveal mass independently fractionated (MIF) Hg isotopes in OIB, from Samoa (negative MIF), Pitcairn (negative MIF), and Tubuai (positive MIF). These data suggest that Hg from surface reservoirs was recycled in the mantle sources of ocean island basalts.