Discovery of eclogite at northern margin of Qaidam Basin, NW China

Eclogite was first discovered at the northern margin of the Qaidam Basin in this study. It occurs as pods in the gneiss sequence of Middle to Upper Proterozoic age and is mainly composed of garnet, omphacite, phengite and rutile. The garnets contain 44%–62% of almandine, 15%–33% of grossular and 12%–30% of pyrope molecules, and the omphacites contain 40%–46% of jadeite. Applying garnet-clinopyroxene thermometry and jadeite geobarometry, the peak conditions of eclogite facies metamorphism occurred at about (722±123)°C and at the pressure of up to c. 22 × 10⁸ Pa.