Apatite in the mantle

Implications for metasomatic processes and high heat production in Phanerozoic mantle

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

*Corresponding author for this work

    Research output: Contribution to journalArticle

    203 Citations (Scopus)

    Abstract

    The abundance of apatite in Phanerozoic mantle may be greatly underestimated. This study shows that apatite has a widespread occurrence in Phanerozoic lithospheric mantle and can be divided into two geochemically distinct types using halogen content, presence or absence of structural CO2, Sr and trace element (especially U, Th, and light rare earth) ratios and abundances, and association with either metasomatised mantle wall-rock peridotites (Apatite A) or high-pressure magmatic crystallisation products (Apatite B). Apatite A is inferred to result from metasomatism by CO2- and H2O-rich fluids derived from a primitive mantle source region, while Apatite B compositions are consistent with crystallisation from magmas within the carbonate-silicate compositional spectrum. The presence of significant apatite in the lithospheric mantle is important not only for the geochemical budget but also for assessing heat production and heat flow in the mantle. The measured U and Th contents of mantle apatite average 60 and 200 ppm, respectively and 0.5% apatite would dominate heat production. Metasomatised mantle may also contain amphibole and mica with K2O and clinopyroxene with detectable U and Th. In lithospheric mantle with a thickness of 70 km, this abundance of apatite would result in mantle heat flow contribution of about 12 mW / m2, a significant proportion of the total 'normal' mantle heat flow of about 18 mW/m2. (C) 2000 Elsevier Science B.V. All rights reserved.

    Original languageEnglish
    Pages (from-to)217-232
    Number of pages16
    JournalLithos
    Volume53
    Issue number3-4
    DOIs
    Publication statusPublished - 2000

    Fingerprint Dive into the research topics of 'Apatite in the mantle: Implications for metasomatic processes and high heat production in Phanerozoic mantle'. Together they form a unique fingerprint.

  • Cite this