Крупномасштабное фракционирование редкоземельных элементов в мантии кратонов

• Datum: 2007
• ISSN: 1025-6415
• Hauptverfasser: Арясова, О.В., Хазан, Я.М.
• Format: Artikel
• Sprache: Russisch
• Veröffentlicht: Видавничий дім "Академперіодика" НАН України 2007
• Schlagworte: Науки про Землю
• Online Zugang: https://nasplib.isofts.kiev.ua/handle/123456789/2442
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Zitieren: Крупномасштабное фракционирование редкоземельных элементов в мантии кратонов / О.В. Арясова, Я.М. Хазан // Доп. НАН України. — 2007. — N 8. — С. 110-115. — Бібліогр.: 15 назв. — рос.

Rare earth element (REE) abundances in clinopyroxene and garnet from xenoliths entrained by kimberlites of the Kaapvaal craton, South Africa, and the Somerset Island, Canada, show a strong and species-dependent variation vs. pressure in a depth range of 70 to 200 km. As a result, the interelement ratios of the REE vary across the upper mantle. This effect can be referred to as a REE large-scale space fractionation. Based upon a strong correlation between the activation energies of the REE diffusion in clinopyroxene, and the logarithmic slopes Γ of the abundance vs. pressure dependence, Γ = –d log C(P)/dP, we speculate that the space fractionation had accompanied mantle melting events and was due to a nonequilibrium REE partition between the melt and the solid residue. A simplified model of the mantle partial melting, which takes into account a PT dependent diffusive exchange between the melt and the multimineral solid residue and a non-modal character of peridotite melting indicates that the observed strong fractionation is resulted from a high degree (10–20%) partial melting of a depleted peridotite (a few wt% of clinopyroxene).