Abstract:
We report Sr-, Nd- and Pb-isotopic compositions for the lavas of Mauritius, the second youngest volcanic island in the Reunion hotspot. The lavas of the Older Series (7.8-5.5 Ma) have identical isotopic compositions ( (super 87) Sr/ (super 86) Sr = 0.70411 to 0.70422, (super 143) Nd/ (super 144) Nd = 0.512865 to 0.512854, and (super 206) Pb/ (super 204) Pb = 19.016 to 19.041) to those of Reunion, where the center of volcanic activity is currently located. The lavas of the Intermediate Series (3.5-1.9 Ma) and Younger Series (0.70-0.17 Ma) are shifted to lower Sr-isotopic compositions (0.70364-0.70394, with (super 143) Nd/ (super 144) Nd = 0.512813 to 0.512948 and (super 206) Pb/ (super 204) Pb = 18.794 to 18.984). The Intermediate Series lavas have similar trace-element characteristics (e.g. Zr-Nb, Ba-Y) to those of Rodrigues, in both cases requiring the involvement of an enriched mantle-like component in the mantle source. During the volcanic history of Mauritius, the magmas lost the principal isotopic characteristics of the Reunion hotspot with time, and became gradually imprinted with the isotopic signature of a shallower mantle source that produced the Central Indian Ridge basalts.