Enstatite from ophiolite ultramafic rocks: plastic deformation and related chemical changes
D.E. Saveliev, S.N. Sergeev
The results of study of plastically deformed enstatite from mantle peridotites of the central kraka massif (south urals) are presented. Acase of orientation of stress feld of peridotite unfavorable for activation of a single possible slip system of enstatite – (100) and accommodation of deformation by means of lattice rotation is considered. It is shown that crystal bending results in formation of lamellae in a sliding surface and, then, decomposition, which leads to the formation of two complementary assemblages: 1) low-temperature with pargasite, olivine fo75, sulfdes, and ni-fe solid solutions and 2) refractory including depleted enstatite II, forsterite and newly formed tiny spinel grains. A role of plastic deformation for initiation of partial melting and formation of new grains of chromite is discussed.
Figures 9. Tables 6. References 39.
Key words: ultramafc rocks, plastic deformation, enstatite, pargasite, recrystallization, partial melting, south urals, kraka.
МINERALOGY № 1 2018