Geophysical evidence for chemical variations in the Australian continental mantle

L.P.A. van Gerven, F. Deschamps, R.D. Hilst

    Research output: Contribution to journalArticleAcademicpeer-review

    21 Citations (Scopus)

    Abstract

    The relative density-to-shear velocity scaling (¿) provides a diagnostic for the presence of compositional variations in the mantle. We invert shear-wave velocity from a recent 3-D model and gravity anomalies for radial profiles of ¿ of the uppermost mantle beneath Australia. We performed calculations for the three major tectonic provinces that constitute the continent, and found significant differences between them. The ¿ profile for the Phanerozoic region can be explained by thermal variations alone. In contrast, negative values of ¿ suggest that variations in composition are important between ~75 and ~150 km depth in the Proterozoic continental lithosphere (central Australia). It is likely that chemical variations are also required to explain the inferences for the Archean craton (west Australia), but poor tomographic resolution precludes a definitive conclusion. The scaling factors found are consistent with chemical depletion of deep Precambrian lithosphere, which supports a tectosphere model for the Australian continental roots
    Original languageEnglish
    JournalGeophysical Research Letters
    Volume31
    Issue number17
    DOIs
    Publication statusPublished - 2004

    Keywords

    • uppermost mantle
    • gravity-field
    • flow models
    • tectosphere
    • inversion
    • heterogeneity
    • lithosphere
    • observables
    • temperature
    • tomography

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