Zinc isotopes trace sediment recycling in the Lesser Antilles
Description
To identify subducted materials and their transfer mechanisms into the mantle wedge, this study presents Zn isotope compositions for 22 arc lava samples from seven Lesser Antilles volcanoes and 50 marine sediment samples from DSDP Sites 543 and 144, combined with major-trace elements and radiogenic isotopes. Sediments exhibit significant Zn isotopic variations (δ66Zn = −0.15‰ to 0.50‰), primarily controlled by mineralogy. Clay-rich sediments from Site 543 are enriched in light Zn isotopes, suggesting an association with weathering intensity. In contrast, carbonate-rich sediments from Site 144 are isotopically heavy, with their biogenic carbonates likely recording deep seawater Zn isotopic compositions. Arc lavas display significant Zn isotopic variations (0.17‰ to 0.39‰) relative to MORB, reflecting recycled material contributions to mantle wedge. Integrated major-trace elements and Sr-Nd-Zn isotopes collectively support that recycled materials (sediments, AOC, and possibly serpentinites) were incorporated into the mantle wedge as mélange. This study highlights Zn isotopes as an effective tool for tracing sediment recycling and physical transfer mechanisms in subduction zones.