Emplacement of ophiolitic rocks in forearc areas: Examples from central Japan and Izu-Mariana-Yap island arc system

Summary Recent results of ocean dredging of ophiolitic rocks in forearc areas in the west Pacific region are summarized and discussed together with the field data in the ophiolitic belts in the Setogawa and Mineoka forearc belts in central Japan. Metamorphism, deformation and sedimentation of the dismembered ophiolites in these regions indicate that they were emplaced at first in transform-fault areas or oceanic fracture zones, and they became the subsequent zones of initiation of subduction. Sometimes the mass of dismembered ophiolite was tectonically and sedimentarily mixed with island-arc materials and incorporated into the forearc belts during subsequent forearc tectonics.

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