Fig. 2.

Magnesium isotopic composition of Martinique arc lavas and subducting forearc sediments (sites 144 and 543). (Data are reported in Tables S1 and S2.) Data sources for the other reservoirs are from several references (18, 22–24, 36, 42, 43,*,†,‡). The vertical solid line and gray bar represent the average δ²⁶Mg and 2 SD of normal mantle, as sampled by global peridotite xenoliths (−0.25 ± 0.04) (18). The short bold black vertical lines represent the mean δ²⁶Mg value of each individual reservoir.