This project is for a Hf and (where needed) Nd isotopic study of (1) a wide-ranging set of granites derived from crustal sources that were old at time of melting, and (2) a reference suite of granites derived from juvenile sources. Samples will be from the PIs'own collections, from other published studies and from a proposed new collection of 1.4 Ga granites from the S.W. USA. Also planned is a study of the resilience of the Lu-Hf isotopic system in deformed/altered rocks. Lu-Hf, Sm-Nd and Rb-Sr results for a mylonitized Proterozoic granite are described, and studies of changes that occur in potassic metasomatism, in HCl-rich and in F-rich alteration environments are planned.
