Ofioliti

Volume 25, Issue No. 1, 2000

GEOCHEMICAL AND MINERALOGICAL ASPECTS OF CR-BEARING AMPHIBOLES FROM RODINGITES OF THE ELISTRATOVA PENINSULA (KORYAKIA, RUSSIAN FAR EAST)

A.B. Osipenko*, V.V. Kononov* and V.M. Chubarov*

*Institute of Volcanology, Russian Academy of Sciences, Petropavlovsk-Kamchatsky, Russia

ABSTRACT
Tremolitic amphiboles with unusually high Cr2O2 contents (up to 4.27 wt %) were found among calc-silicate metasomatites (rodingites) in the ophiolite complex of the Elistratova Peninsula (SW Koryakia). Incorporation of chromium in a crystal lattice of the studied minerals is caused by "pargasite" and "edenite" types of substitution and results in positive correlation of chromium with aluminum in the tetrahedral coordination in the structural formula. The amphiboles significantly enriched in chromium presumably develop after primary magmatic minerals with small Cr-spinel inclusions owing to metasomatic alteration.

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