Zr–LREE rich minerals in residual peraluminous granulites, anotherudfactor in the origin of low Zr–LREE granitic melts?

摘要

There is a significant enrichment in some trace elements in the major residual minerals of peraluminous granulite xenoliths fromudthe lower crust. Those trace elements are released from the breakdown of accessory phases at high-T granulite-facies conditionsud(N850 °C). Around 10–35% of Zr is hosted in granulite rutile and garnet, whereas, the entire LREE–Eu budget is controlled byudfeldspar. The Zr- and REE-compatible behaviour of the major granulite phases, combined with the scarcity of accessory phases,udwhich are mostly included in major granulite minerals, leads to a disequilibrium in accessory dissolution in the peraluminousudpartial melts. Thus the melt extracts less Zr and LREE and, consequently, generates the false impression of having lower-T whenudapplying current accessory phase dissolution models.