Geochemistry and tectonic setting of the Munabulak ophiolites in Xinjiang

The Munabulak ophiolites as the largest ophiolitic mélange zone in Xinjiang are made up of ultramafic rocks,mafic rocks,light-coloured rocks and meta-basalts which may be traced back to the Jixianian of the Mesoproterozoic for their formation and the early Qingbaikouan of the Neoproterozoic for their emplacement,and represent the subduction zone in the Altun region during the Mesoproterozoic.These ophiolites may be originated from the small spreading oceanic ridges of back-arc or inter-arc restricted oceanic basins,and finally emplaced into the deep-sea sediments constituting the ophiolites in orogenic zones.