Mantle-genetic tremolite in metamorphic peridotite from Kuda, China

摘要

The mantle-genetic pargasites in peridotite inclusion of basalt have been studied, but the mantle-genetic tremolite has not been reported in past studies. Four kinds of assemblage with tremolite in metamorphic peridotite from Kuda, Xinjiang will be reported in this note. The Kuda ophiolite occurs in Kunlun orogenetic belt and was formed in the period from Sinian to Early Ordovician. The metamorphic peridotite in ophiolite is a tectonic exotic block napp and is a highly depleted harzburgite, which consists of forsterite (Fo = 9l), enstatite (En = 90 -- 95), chromespinel (Cr/ (Cr+Al) =0.5 -- 0.61) and very little of clinopyroxene. The exsolution lamellae in pyroxene and Kink bandings in olivine can be observed clearly under a microscope. The plastic deformation fabrics, such as free dislocation, dislocation wall and subgrain structure, can also be observed in decorated olivines. The minerals in the studied rock samples are very fresh, which offers a good condition for this study.