Controls on the magnitude of Ce anomalies in zircon

Increases in the magnitude of positive Ce anomalies zircons from igneous rocks are often interpreted to be controlled by progressive melt oxidation and have been used provide evidence for elevated redox state magmas associated with porphyry Cu deposits. In this paper, we test idea comparing trace element compositions Resolution Cu-Mo deposit, Arizona, numerical models systematics zircon-melt partitioning. We show that although (estimated chondrite-normalised ratio Nd) may increase over an order throughout period zircon crystallisation, oxybarometric estimates fact indicate a constant during time. employ Monte Carlo approach model evolution anomaly as function temperature, fO2, composition, compare our against literature data chemically well-constrained volcanic rocks. find large increases can reproduced cooling at fixed effect is magnified increasing Ce/Nd ratio, which driven co-crystallisation amphibole, apatite especially titanite. not sufficient explain high some hydrous, oxidised hypabyssal rocks, additionally require combination titanite low crystallisation temperature. therefore caution interpretation solely context fO2 variation.