Olivine-chrome-spinel equilibrium in chromitites and ultramafites of Rai-Iz massif, Polar Urals

Abstract

Olivine and chrome-spinel compositions from chromitites and ore-bearing metamorphosed ultramafic rocks of Rai-Iz massif were compared. It was established that olivine and spinel ferruginosity are directly proportional and increase monotonically from chromitites to ultramafic rocks that indicates the existence of equilibrium in the ore-rock system. The compositions of accessory spinel are in agreement with compositions of ferrichromite and chromemagnetite, which are highly oxidized spinel group minerals, typical for metamorphic ultramafic rocks. The obtained results suggests that chromitites and metamorphosed ultramafic rocks are products of a single process which is metamorphic differentiation of ultramafic rocks.

Keywords

• хромититы
• оливин-шпинелевое равновесие
• метаморфизм
• рудообразование
• массив рай-из
• chromitites
• olivine-spinel equilibrium
• metamorphism
• ore genesis
• rai-iz massif