Details

Autor(en) / Beteiligte

• Dong, Miao
• Lü, ChuanChuan
• Zhang, Jian
• Hao, Tianyao

Titel

Downgoing Plate‐Buoyancy Driven Retreat of North Sulawesi Trench: Transition of a Passive Margin Into a Subduction Zone

Ist Teil von

• Geophysical research letters, 2022-12, Vol.49 (23), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The transition of a passive continental margin into a subduction zone remains a hypothesis because few geological cases have been reported. The North Sulawesi subduction zone is a 5–9 myr system in Southeast Asia that has evolved from a passive continental margin and has long been overlooked by studies of passive to active margin transitions. Here we compare geophysical evidence from the region with our numerical simulation results. We find that the initial subduction of North Sulawesi relies on horizontal stress, where the trench retreat depends on the negative buoyancy of the oceanic lithosphere. Furthermore, less space available for subduction leads to reduced mantle flow caused by subduction and slower trench retreat. These new dynamical constraints indicate that the negative buoyancy of the oceanic plate is a key factor for the trench retreat, even though subduction initiated was induced. Plain Language Summary The transition from a passive margin to a subduction zone is a key process of the Earth. Our understanding of the dynamic mechanism behind this process is still ambiguous. The North Sulawesi Trench provides unique opportunities to study this phenomenon. Since it is located in an area where plates converge, its formation and retreat have thought to have been driven by the collision of the surrounding plates. However, our numerical simulations suggest that subduction initiation was caused by compression due to convergence between other plates, but subsequent trench retreat is a consequence of the negative buoyancy of the subducted plate itself. Mantle convection driven by slab subduction plays an important role in trench retreat and overriding plate deformation. The rotation of the North Arm of Sulawesi is also not due to the collision of the surrounding plates, but because the trench retreats more slowly on its eastern side than on its western side. The reason for the differential retreat is that the subduction space on the eastern side of the trench is reduced by the Sangihe slab. Key Points Subduction initiation of the North Sulawesi subduction zone is induced, but the trench retreat is driven by the subducted plate itself Subduction‐driven mantle flow plays a vital role in trench motion and upper plate deformation The reason for the current clockwise rotation of the North Arm of Sulawesi is due to the presence of the underlying Sangihe slab