The origin of intraplate basalts remains controversial, despite numerous isotope and seismic studies. Here we employ thermodynamic modeling with MAGEMin to integrate the Sr-Nd-Hf isotopes of basaltic volcanics with the seismic velocities of their mantle source. The results indicate that residual garnets generate high P-wave velocity anomalies in the mantle, and impart distinctive time-integrated εNd-εHf isotope signatures to the partial melts (i.e., the erupted basaltic magmas). Since the garnet-spinel transition (~42-60？km) is always shallower than the lithosphere-asthenosphere boundary (~70-100？km), garnet effects may serve as an indicator of thermal magmatic events. These findings suggest that the widely distributed Cenozoic intraplate basalts in Eastern China originated from the lithospheric mantle (<~60？km) that didn’t retain garnet. Two notable exceptions are the Wudalianchi and Nuominhe basalts, which originate from the asthenosphere (~100-140？km) and the lithosphere-asthenosphere transition, respectively. The integrated radiogenic isotope-seismic velocity framework can be applied to intraplate basalts globally.
Article link: https://doi.org/10.1038/s43247-025-03024-3
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