Resetting of the U-Pb zircon system in Cambro-Ordovician intrusives of the deep freeze range, Northern Victoria Land, Antarctica

R. M. Bomparola*, C. Ghezzo, E. Belousova, W. L. Griffin, Suzanne Y. O'Reilly

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    59 Citations (Scopus)

    Abstract

    A detailed in situ isotopic (U-Pb, Lu-Hf) and geochemical study of zircon populations in a composite sequence of foliated to massive Cambro-Ordovician intrusions in the Deep Freeze Range (North Victoria Land, Antarctica), has highlighted great complexity in zircon systematics. Zircons in deformed granitoids and tonalites display complex internal textures, a wide spread of concordant U-Pb ages (between 522 and 435 Ma) and unusual trace-element compositions (anomalous enrichment of light rare earth elements, U, Th and Y) within single zircon grains. In contrast, zircons from undeformed samples display a limited range of U-Pb ages and trace-element compositions. Zircons from all age and textural populations in most of the deformed and undeformed samples show a relatively narrow range of εHf values, suggesting that the Lu-Hf system remained undisturbed. Inferred emplacement ages cover a time interval of about 30 Myr: from 508 to 493 Ma for the oldest strongly foliated synkinematic Howard Peaks megacrystic monzogranites and high-K calc-alkaline mafic to intermediate rocks of the 'Corner Tonalite' unit; from about 489 to 481 Ma for the younger massive shoshonitic mafic dyke suite and the high-K calc-alkaline Keinath granite. The observed isotopic and chemical variations in zircon are attributed to a sub-solidus recrystallization under hydrous conditions and varying temperature, in a setting characterized by a transpressional to extensional stress regime.

    Original languageEnglish
    Pages (from-to)327-364
    Number of pages38
    JournalJournal of Petrology
    Volume48
    Issue number2
    DOIs
    Publication statusPublished - 2007

    Fingerprint Dive into the research topics of 'Resetting of the U-Pb zircon system in Cambro-Ordovician intrusives of the deep freeze range, Northern Victoria Land, Antarctica'. Together they form a unique fingerprint.

    Cite this