Relating zircon and monazite domains to garnet growth zones: Age and duration of granulite facies metamorphism in the Val Malenco lower crust

J. Hermann*, D. Rubatto

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    353 Citations (Scopus)

    Abstract

    Zircon from a lower crustal metapelitic granulite (Val Malenco, N-Italy) display inherited cores, and three metamorphic overgrowths with ages of 281 ± 2, 269 ± 3 and 258 ± 4 Ma. Using mineral inclusions in zircon and garnet and their rare earth element characteristics it is possible to relate the ages to distinct stages of granulite facies metamorphism. The first zircon overgrowth formed during prograde fluid-absent partial melting of muscovite and biotite apparently caused by the intrusion of a Permian gabbro complex. The second metamorphic zircon grew after formation of peak garnet, during cooling from 850 °C to c. 700 °C. It crystallized from partial melts that were depleted in heavy rare earth elements because of previous, extensive garnet crystallization. A second stage of partial melting is documented in new growth of garnet and produced the third metamorphic zircon. The ages obtained indicate that the granulite facies metamorphism lasted for about 20 Myr and was related to two phases of partial melting producing strongly restitic metapelites. Monazite records three metamorphic stages at 279 ± 5, 270 ± 5 and 257 ± 4 Ma, indicating that formation ages can be obtained in monazite that underwent even granulite facies conditions. However, monazite displays less clear relationships between growth zones and mineral inclusions than zircon, hampering the correlation of age to metamorphism. To overcome this problem garnet-monazite trace element partitioning was determined for the first time, which can be used in future studies to relate monazite formation to garnet growth.

    Original languageEnglish
    Pages (from-to)833-852
    Number of pages20
    JournalJournal of Metamorphic Geology
    Volume21
    Issue number9
    DOIs
    Publication statusPublished - Dec 2003

    Fingerprint

    Dive into the research topics of 'Relating zircon and monazite domains to garnet growth zones: Age and duration of granulite facies metamorphism in the Val Malenco lower crust'. Together they form a unique fingerprint.

    Cite this