Geocheminar fall-2017

We report the first detailed study of Si isotopes in zircon, coupled with simultaneous detection of O isotope ratios, to better understand the relationship between crustal weathering and recycling. Current knowledge about Si isotopes shows their potential to complement and enhance that understanding because weathering of the crust typically results in a residuum with lower ³⁰Si (where δ³⁰Si is the deviation in ‰ of a sample’s ³⁰Si/²⁸Si ratio to that of a standard) when compared to ‘fresh’ igneous material. Samples explored include zircons from S-, I-, and A-type Phanerozoic granitoids, and detrital zircons from the Jack Hills. We also explore the relationship between the δ³⁰Si value of individual minerals and the whole rock by quantifying high temperature Si isotope fractionations by experiment.