Numerical modeling of North Sulawesi subduction zone: Implications for the East-West differential evolution

Geological observations have revealed a rapid evolution and obvious east–west difference in the North Sulawesi subduction zone. The Celebes Sea plate has inserted itself under the north arm of the Sulawesi Islands and the north arm of the Sulawesi Islands has rotated clockwise at the same time. The rotation of the north arm of the Sulawesi Islands may play an important role in facilitating tectonic processes like the slab rollback of the Celebes Sea plate. In view of the east–west differences along the north Sulawesi subduction zone, a numerical model with the convergence rate of the plates as the basic variable is established to quantitatively describe the evolution process of the north Sulawesi subduction zone. Our results reproduce the east–west differences of the subducting Celebes Sea plate, showing a shallow–deep–shallow subduction style. We suggest that the variable velocity ratio of the overriding plate to the subducting slab may be the main reason for the differential subduction along the strike of the North Sulawesi subduction zone. We therefore conclude that the residual slab and the rate of the eastern continental plate limit the downward movement of the subducted slabs of the eastern Sulawesi, and the tectonic location beyond the rotation radius influences the subduction morphology of the extreme western Sulawesi. Moreover, the widespread extension since Pliocene at the western Sulawesi is not affected by the rotating overriding plate.

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