Rapid magmatic processes accompany arc-continent collision: the Western Bismarck arc, Papua New Guinea

Heather Cunningham, Jim Gill, Simon Turner*, John Caulfield, Louise Edwards, Simon Day

*Corresponding author for this work

    Research output: Contribution to journalArticle

    8 Citations (Scopus)

    Abstract

    New U-Th-Ra, major and trace element, and Sr-Nd-Pb isotope data are presented for young lavas from the New Britain and Western Bismarck arcs in Papua New Guinea. New Britain is an oceanic arc, whereas the latter is the site of an arc-continent collision. Building on a recent study of the Manus Basin, contrasts between the two arcs are used to evaluate the processes and timescales of magma generation accompanying arc-continent collision and possible slab detachment. All three suites share many attributes characteristic of arc lavas that can be ascribed to the addition of a regionally uniform subduction component derived from the subducting altered oceanic crust and sediment followed by dynamic melting of the modified mantle. However, the Western Bismarck arc lavas diverge from the Pb isotope mixing array formed by the New Britain and the Manus Basin lavas toward elevated Pb-208/Pb-204. We interpret this to reflect a second and subsequent addition of sediment melt at crustal depth during collision. U-238 and Ra-226 excesses are preserved in all of the lavas and are greatest in the Western Bismarck arc. High-Mg andesites with high Sr/Y ratios in the westernmost arc are attributed to recent shallow mantle flux melting at the slab edge. Data for two historical rhyolites are also presented. Although these rhyolites formed in quite different tectonic settings and display different geochemical and isotopic compositions, both formed from mafic parents within millennia.

    Original languageEnglish
    Pages (from-to)789-804
    Number of pages16
    JournalContributions to mineralogy and petrology
    Volume164
    Issue number5
    DOIs
    Publication statusPublished - Nov 2012

    Keywords

    • Papua New Guinea arcs
    • Arc lavas
    • Continent-arc collision
    • U-series isotopes
    • U-SERIES DISEQUILIBRIA
    • BRITAIN ISLAND-ARC
    • LOWER CRUST
    • SLAB
    • SUBDUCTION
    • KAMCHATKA
    • CONSTRAINTS
    • EVOLUTION
    • GENESIS
    • BENEATH

    ASJC Scopus subject areas

    • Geochemistry and Petrology
    • Geophysics

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