Barium Isotope Fingerprint for Recycled Ancient Sediment in the Source of EM1‐Type Continental Basalts

Abstract The origin of enriched mantle 1 (EM1) endmember, characterized by low 206 Pb/ 204 Pb and 143 Nd/ 144 Nd ratios in ocean island basalts, has long been debated. This is because melting of surrounding peridotite, together with the EM1 component, can dilute the “EM1 fingerprints” in these rocks. Here, we present barium isotope data for well‐characterized EM1‐type continental basalts from northeast China to constrain their nature and origin. Our results show that these basalts have δ 138/134 Ba values ranging from −0.1‰ to 0.08‰, which are lower than the depleted MORB mantle. Correlations between δ 138/134 Ba and K/U, Ba/Th, U/Pb, ε Nd and 206 Pb/ 204 Pb suggest a heterogeneous source involving binary mixing between the lithospheric mantle and an EM1 component. The EM1 component, characterized by light δ 138/134 Ba and low 206 Pb/ 204 Pb ratios, can be attributed to the addition of recycled ancient sediments to the source. This study indicates that Ba isotopes have potential to trace crustal material recycling into Earth's deep mantle.