The origin of boninite - Recycle of Archean-Proterozoic slab

Abstract

Boninites in the western Pacific extruded during the early stage of the subduction zone development. We discuss the genetic relationships of boninite and antecedent protoarc basalt magmas based on the T-P conditions and Pb-Hf-Nd isotopic modeling. Yb-Os isotopic modeling demonstrates that the high-Si boninite source formed by18−30 wt% melting of the primitive upper mantle at 1.5−1.7 Ga, whereas the source mantle of the protoarc basalt experienced only 3.5−4.0 wt% melt depletion at 3.6−3.1 Ga.