Tungsten isotopes of intraplate basalts and implications for deep W recycling

Tungsten isotopes of subducted materials have been extensively investigated at sub-arc depths, yet W recycling into the deeper mantle remains poorly constrained. We present the first stable W isotope data from Cenozoic intraplate basalts in eastern China. These basalts display light W isotopes (δ¹⁸⁶W = 0.020–0.074‰) compared to MORB, complementing to most arc magmas. Coupled with low W/Th but high Nb/U, TiO₂/Al₂O₃, and Ce/Pb ratios, these signatures indicate a deep mantle source modified by the stagnant Pacific oceanic crust in the mantle transition zone. Systematic trends of decreasing δ¹⁸⁶W with increasing (⁸⁷Sr/⁸⁶Sr)_i but decreasing ε_Nd(t) and Ce/Pb, from basanites to tholeiitic basalts, reflect deep mantle heterogeneity and increasing contributions from subducted sediments. We suggest melts derived from the recycled residual slab metasomatize the big mantle wedge, generating the low-δ¹⁸⁶W basalts. Therefore, W isotopes in continental basalts provide a powerful means to trace the recycled crustal components into deep mantle.