Тип публикации: статья из журнала

Год издания: 2024

Идентификатор DOI: 10.3749/2300071

Аннотация: <jats:title>Abstract</jats:title> <jats:p>Two generations of hypermagnesian clinopyroxene [92 < Mg# < 98] are found in the Yanisvaara ultrabasic complex in the northwestern Lapland–Belomorian Belt, Kola Peninsula, Russia. Grains of a first generation (Wo47.3–50.7En46.5–49.4Fs2.5–3.5), 0.2–0.4 mm across, are attributed to a reactionПоказать полностьюin which tremolite + clinopyroxene replaced orthopyroxene. The second generation generally attains even more strongly magnesian compositions (Wo46.5–50.9En47.5–50.8Fs1.0–3.2). It is sporadically developed as submicrometric rim- or veinlet-like grains associated with tremolite and domains of fresh olivine with Mg# in the range 80.5–82.5 to 87.7–88.0. The later generation of clinopyroxene crystallized at elevated values of fO2 under closed-system autometasomatic conditions rather than during regional metamorphism. The compositions attained in three representative samples are highly magnesian, but characteristically poor in Cr compared to primary clinopyroxene. Compositions of the accompanying silicate, oxide, and sulfide minerals are provided. A novel Ni-Mn oxyspinel may be related to hausmannite. Yanisvaara and coeval subvolcanic komatiitic complexes are inferred to have degassed, which promoted the rapid rise in fO2 and indirectly promoted the buildup of Mg in the late clinopyroxene.</jats:p>

Журнал: The Canadian Journal of Mineralogy and Petrology

Выпуск журнала: Т. 62, № 5

Номера страниц: 765-780

ISSN журнала: 28171713

Место издания: Quebec

Издатель: Mineralogical Association of Canada

• Barkov Andrei Y. (Research Laboratory of Industrial and Ore Mineralogy, Cherepovets State University, 5 Lunacharsky Avenue, Cherepovets 162600, Russia)
• Nikiforov Andrey A. (Research Laboratory of Industrial and Ore Mineralogy, Cherepovets State University, 5 Lunacharsky Avenue, Cherepovets 162600, Russia)
• Martin Robert F. (Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, Quebec H3A 0E8, Canada)
• Korolyuk Vladimir N. (V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Science, 3 Avenue Prospekt Koptyuga, Novosibirsk 630090, Russia)
• Silyanov Sergey A. (Institute of Non-Ferrous Metals and Material Science, Siberian Federal University, 95 Krasnoyarskiy Rabochiy pr., Krasnoyarsk 660025, Russia)

• Ядро РИНЦ (eLIBRARY.RU)