Figure 4

The depth–velocity profiles of δ-Fe13 and PREM³⁶: (a) v_S, (b) v_Φ, and (c) (v_S − v_Φ)/v_Φ. The plots of δ-Fe13 at room T (solid circle) and mantle T (open circle) indicate the velocities of δ-Fe13 at room temperature and along an average mantle geotherm⁴⁸, respectively. The calculation procedure of v_S and v_Φ of δ-Fe13 under these conditions is explained in the main text. The velocities of δ-Fe13 shown in this figure are determined using the density of δ-Fe13-r2 with natural mass of Fe. The dotted gray lines indicating − 2% of v_S and + 1% of v_Φ relative to PREM (solid gray lines) are regarded as reasonable perturbations for each respective velocity within the LLSVPs, based on the SB10L18 model²⁷. The degree of anti-correlation between v_S and v_Φ in δ-Fe13 is considered to be larger than the maximum anti-correlation observed in the LLSVPs. Estimated uncertainties for δ-Fe13 are shown by the vertical bars. The numerical values for the data shown in this figure are available in Table S3.