OIB-type rocks within West Junggar ophiolitic mélanges: Evidence for the accretion of seamounts

The seamounts formed in West Junggar as well as the Paleo-Asian Ocean at Neoproterozoic. With progressive evolution of the Paleo-Asian Ocean, subduction of the oceanic lithosphere commenced during late Cambrian to early Ordovician, resulted in the seamounts eventually accreted in the fore-arc with oceanic fragments forming the Tangbale and Mayile ophiolitic mélanges. As retreat of the subducting slab, the subduction-accretion processes may have continued in the late Paleozoic, given rise to form the Darbut and karamay ophiolitic mélange with the OIB-type rocks from seamounts. Based on our observations, and in combination with previous work, we suggest that the intra-plate magmatism in the CAOB might generally continuous during the development of the Paleo-Asian Ocean from the Late Neoproterozoic to the Mesozoic. Therefore, we present a new model that is multiple intra-oceanic subduction with seamount accretion for the CAOB, which can better explain the tectonic evolution of the CAOB.