Rates of Magma Ascent: Constraints from Mantle-Derived Xenoliths

Suzanne Y. O'Reilly*, W. L. Griffin

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

    29 Citations (Scopus)

    Abstract

    The rates of ascent of magmas through the lithosphere can be estimated by a variety of methods using physical and compositional parameters of lithospheric mantle fragments brought to the surface in these magmas. The xenoliths are relatively dense, and the magma must be ascending more rapidly than the xenoliths can sink through it. These methods suggest an average ascent rate through the whole lithosphere (mantle and crust) in the range of 0.2 to 0.5 m s-1 (about 0.5 to 2 km/ hour). The ascent rates through the shallow crust may be much higher: 20 m s-1 and up to supersonic speeds ( 300 m s-1) in the uppermost crust. Residence times derived from microstructural observations in recrystallised minerals in the xenoliths and element diffusion profiles in xenolith minerals suggest ascent rates in the range of 0.2 to 0.4 m s-1. These methods all provide minimum velocities ranging from about 0.2 to 2 m s-1 for relatively low-volume melts such as alkali basalts, to 4 to 40 m s-1 (and up to supersonic) for volatilecharged ultramafic melts such as kimberlites. In summary, magmas carrying mantle xenoliths much reach the surface within a maximum of about 8 to 60 hours of picking up these dense fragments from depths of about 200 to 80 km depth.

    Original languageEnglish
    Title of host publicationTimescales of Magmatic Processes
    Subtitle of host publicationFrom Core to Atmosphere
    EditorsAnthony Dosseto, Simon P. Turner, James A. Van-Orman
    Place of PublicationOxford
    PublisherJohn Wiley & Sons
    Pages116-124
    Number of pages9
    ISBN (Print)9781444332605
    DOIs
    Publication statusPublished - 30 Nov 2010

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