Monosulfide solid solution (mss) in lherzolite xenolith from Ichinome-gata, Akita Prefecture, Japan

Abstract

Iron-nickel monosulfide solid solution (mss) was found in spinel lherzolite xenoliths from Ichinome-gata, Akita Prefecture, Japan. The mss occurs as bleb-like form in ortho- and clinopyroxenes associating with olivine, chromian spinel and pargasite. It is mono-mineral and contains 32.99-40.20 atomic% Fe, 5.76-13.01 atomic% Ni and 0.53-0.92 atomic% Cu. Ortho- and clinopyroxenes including mss blebs have composition of 89.7-90.3 and 88.9-90.5 in atomic ratio of 100 Mg/(Fe+Mg), respectively. Olivine associating with ortho- and clinopyroxenes ranges from 89.4 to 91.0 in atomic ratio of 100 Mg/(Fe+Mg) and contains 0.25-0.37 wt% Ni.
     Mss is thought to be in disequilibrium with olivine in terms of Fe-Ni partitioning and to have been formed during metasomatic processes at high temperature in the upper mantle.