Jurassic oceanic lithosphere beneath the southern Ontong Java Plateau: Evidence from xenoliths in alnöite, Malaita Solomon Islands

Akira Ishikawa, Eizo Nakamura, John J. Mahoney

    Research output: Contribution to journalArticlepeer-review

    21 Citations (Scopus)

    Abstract

    The least metasomatized xenoliths of spinel Iherzolite and gabbro recovered from alnöite intruding crust of the southern Ontong Java Plateau on the island of Malaita yield an Sm-Nd age of ca. 160 Ma and an initial εNd value of ∼+8. In contrast, the plateau basement is ca. 120 Ma with initial εNd between +3.7 and +6.5. The xenoliths appear to represent normal Pacific oceanic lithosphere (uppermost mantle and lower crust) formed ∼40 m.y. before the plateau, indicating that the southern part of the plateau was emplaced off axis on mature seafloor. The closest 160 Ma seafloor to Malaita is >1800 km to the north, off the northeastern margin of the plateau, implying the presence of either an intervening large-offset fracture zone or a triple junction. The presence of significantly older oceanic lithosphere beneath the plateau places restrictions on proposed origins for the plateau.

    Original languageEnglish
    Pages (from-to)393-396
    Number of pages4
    JournalGeology
    Volume33
    Issue number5
    DOIs
    Publication statusPublished - May 1 2005

    Keywords

    • Mantle plume
    • Oceanic lithosphere
    • Ontong Java Plateau
    • Sm-Nd age
    • Xenoliths

    ASJC Scopus subject areas

    • Geology

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