Development of P-rich granites by sequential restite fractionation and fractionational crystallisation

The Koetong Suite in the Lachlan Fold Belt

B. W. Chappell*, A. J R White

*Corresponding author for this work

    Research output: Contribution to journalArticle

    19 Citations (Scopus)

    Abstract

    Among the S-type granites of south-eastern Australia, the extensive Koetong Suite shows a wide range of compositions. The variation resulted from two processes. At more mafic compositions, it was induced by varying degrees of separation of a primary melt containing ~ 70% SiO 2 from restite with which it formed in equilibrium in the source. There was no significant change in phosphorus contents during that stage of evolution. In the more felsic granites variation resulted from fractional crystallisation of the primary melt. Elements such as rubidium and tin increased in abundance while others such as strontium and zirconium decreased in amount. In these strongly peraluminous compositions, fractional crystallisation lead to significantly higher phosphorus contents.

    Original languageEnglish
    Pages (from-to)23-27
    Number of pages5
    JournalActa Universitatis Carolinae, Geologica
    Volume42
    Issue number1
    Publication statusPublished - 1998

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