Mg-Sr isotopes of low-δ²⁶Mg basalts tracing recycled carbonate species: Implication for the initial melting depth of the carbonated mantle in Eastern China

Recent studies show that crustal carbonates recycled into the mantle can be traced using Mg isotopes of basalts. However, the species of recycled carbonates are poorly constrained. Carbonates have lower δ26Mg values and higher 87Sr/86Sr ratios relative to the mantle, but different carbonate species display different mixing curves with the mantle in the Mg-Sr isotopic diagram because of differences in their Sr and Mg contents. Thus a combined...