Progress and Prospect of the Darbut Ophiolite in West Junggar,Central Asian Orogenic Belt
Ophiolite is a major material for studying of ancient oceans and important lithological evidence for delineating ancient plate boundaries.It records valuable information from the initial formation of the oceanic lithosphere to the final closure of the ocean basin,and is also a key geological target for studying the ocean-con-tinent transition process.The Darbut ophiolite in West Junggar is one of the largest and most typical ophiolites exposed in northern Xinjiang.A series of new advances have been achieved in recent years:① Diamonds and other exotic minerals have been recovered from chromitites of the Sartohay ophiolites,thus challenging the pre-vious theory of shallow chromitite genesis.② Fore-arc basalts have been identified in the ophiolite,which is one of the geological records of subduction initiation.③ Ancient seamount material components have been rec-ognized in the ophiolite,in which the basalt show OIB characteristics.④ Sartohay chromitite is the result of deep mantle pre-enrichment and shallow re-enrichment.⑤ A formation environment mainly associated with a subduction-related tectonic setting,with the involvement of the mantle plume,has been suggested.Despite pro-gresses mentioned above,some new scientific issues and research directions have emerged,mainly concerning deep mantle mass recycling processes,subduction initiation mechanisms,crustal growth processes,and subduc-tion zone ophiolite genesis.
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