Why mafic enclaves have higher 87Sr/86Sr ratio than the host granite?

I'm currently researching a I-type calc-alcaline granite with microgranular mafic enclaves. The 87Sr/86Sr ratio of the granite is 0.703-0.706 and the enclaves 0.705-0.706. From the geochemical...

27 June 2020 1,903 4 View