Reported in this paper is the first finding of awaruite in oceanic peridotite. Also described are the petrography of the rocks and the minerals associated with awaruite. It is proved that the awaruite and the associated sulfides pentlandite and hyslewoodite crystallized during different stages of the rock recrystallization under the effect of the oceanic water which had percolated prior to their serpentization. The main factors causing awaruite crystallization in the studied peridotites were the abnormally low oxidation of the initial dunite and harzburgite and the low water/rock ratio during the initial stage of the rock hydration. The presence of awaruite in the study rocks and its oxidation in the coarse of the subsequent serpentization seems to have been the mechanism responsible for the known anomalous enrichment of the hydrothermal solutions of this area in methane and hydrogen. The higher-temperatures of the crystallization of the awaruite-bearing minerals in the oceanic peridotite 450-570o C, compared to the ophiolitic ones, were caused by the natural differences of the peridotite metamorphism in different geodynamic conditions.
awaruite, mineral association abundance, oceanic metamorphism, peridotite.
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