Curtin University Homepage
  • Library
  • Help
    • Admin

    espace - Curtin’s institutional repository

    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item

    Zircon Th/U ratios in magmatic environs

    Access Status
    Fulltext not available
    Authors
    Kirkland, Chris
    Smithies, R.
    Taylor, Richard
    Evans, Noreen
    McDonald, B.
    Date
    2015
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Kirkland, C. and Smithies, R. and Taylor, R. and Evans, N. and McDonald, B. 2015. Zircon Th/U ratios in magmatic environs. Lithos. 212-215: pp. 397-414.
    Source Title
    Lithos
    DOI
    10.1016/j.lithos.2014.11.021
    ISSN
    0024-4937
    School
    Department of Applied Geology
    URI
    http://hdl.handle.net/20.500.11937/37185
    Collection
    • Curtin Research Publications
    Abstract

    A comprehensive database of zircon composition in West Australian magmatic rocks reveals negative correlations between both U and Th zircon/whole rock ratio and the zircon saturation temperature, with the observed change with temperature less for U(zircon/whole rock) than for Th(zircon/whole rock). This observation implies a systematic increase in the zircon/rock ratio with falling crystallisation temperature, a result which replicates findings from experimental partition coefficient studies. Under equilibrium conditions there is a trend to lower zircon Th/U with increasing melt temperature which can be attributed to lattice strain. However, within a fractionating magma, Ti-in-zircon temperatures yield the opposite relationship of lower zircon Th/U in cooler melts. This is due to zircon growth under non-equilibrium conditions with greater incompatibility of Th relative to U, and the removal and segregation of mineral precipitates. These observations can be used as a tool to determine whether zircon growth was in a liquid of similar composition to the observed whole rock. We present an equation that estimates the degree of fractionation between the whole rock composition and the zircon parental liquid. This parameter demonstrates the dissimilarity between the liquid from which the zircon grew and the whole rock composition and aids in distinguishing mesostasis growth in fractionated melt versus cumulate growth in less fractionated magma. We use this ratio to investigate zircon growth in igneous rocks of the Musgrave Province. For a suite of c. 1200Ma magmas that become progressively more fractionated, based on whole rock La/Sm, the fractionation index demonstrates increasing compositional differences between the whole rock and the zircon growth liquid. In the most extreme case independent petrographic evidence indicates mesostasis growth of zircon, whereas in the least fractionated melt zircon growth is established to be close to equilibrium with a zircon saturation temperature of c. 900°C likely being accurate. In contrast, zircon crystals from a rhyolite of the c. 1070Ma Giles Supervolcano have distinctive compositional discordances indicative of antecrystic components. The fractionation factor in this rock implies some zircon growth under higher temperature conditions than the whole rock zircon saturation temperature.

    Related items

    Showing items related by title, author, creator and subject.

    • Sources and conditions for the formation of Jurassic post-orogenic high-K granites in the Western Guangdong Province, SE China
      Huang, Hui-Qing (2012)
      High-K granites have become volumetrically important since at least Proterozoic. Their study bears important implications to crustal and tectonic evolutions. Despite of intensive research, sources and conditions for the ...
    • Sapphirine-bearing Fe-rich granulites in the SW Siberian craton (Angara-Kan block): Implications for Paleoproterozoic ultrahigh-temperature metamorphism
      Sukhorukov, V.; Turkina, O.; Tessalina, Svetlana; Talavera, Cristina (2018)
      We report here for the first time the occurrence of sapphirine-bearing rocks within the Paleoproterozoic granulite complex of the Angara-Kan block (SW Siberian craton) and provide strong evidence for crustal metamorphism ...
    • Petrogenesis of the Cretaceous Zhangzhou batholith in southeastern China: Zircon U–Pb age and Sr–Nd–Hf–O isotopic evidence
      Chen, Jing-yuan; Yang, Jin-hui; Zhang, Ji-heng; Sun, Jin-feng; Wilde, Simon (2013)
      Whole-rock geochemical and Sr–Nd–Hf isotopic data and in situ zircon U–Pb and Hf–O isotopes have been determined for mafic (gabbro and diorite) and felsic (I- and A-type granites) rocks from the Zhangzhou batholith in ...
    Advanced search

    Browse

    Communities & CollectionsIssue DateAuthorTitleSubjectDocument TypeThis CollectionIssue DateAuthorTitleSubjectDocument Type

    My Account

    Admin

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Follow Curtin

    • 
    • 
    • 
    • 
    • 

    CRICOS Provider Code: 00301JABN: 99 143 842 569TEQSA: PRV12158

    Copyright | Disclaimer | Privacy statement | Accessibility

    Curtin would like to pay respect to the Aboriginal and Torres Strait Islander members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Whadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.