Downgoing plate-buoyancy driven retreat of North Sulawesi Trench:
transition of a passive margin into a subduction zone
Miao Dong1,2*,
Tian Yao Hao1,2*, Chuan Chuan
L\(\ddot{\mathbf{u}}\)3, and Jian
Zhang2
1Key Laboratory of Petroleum Resource Research,
Institute of Geology and Geophysics, Chinese Academy of Sciences,
Beijing 100029, China
2University of Chinese Academy of Sciences, Beijing
100049, China
3Bullard Labs, Department of Earth Sciences,
University of Cambridge, Cambridge CB3 0EZ, UK
Corresponding author: Miao Dong
(dongmiao@mail.iggcas.ac.cn)
Tian Yao Hao(tyhao@mail.iggcas.ac.cn)
Key Points:
- Subduction initiation of North Sulawesi subduction zone was induced
but the trench retreat are driven by the subducted plate itself.
- Subduction-driven mantle flows play an important role in trench motion
and upper plate deformation.
- The reason for the clockwise
rotation of the North Arm of Sulawesi at present is the presence of
the Sangihe slab.
Abstract
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 continental passive margin and has long been
overlooked by studies of passive to active margin transitions. Here we
compare geophysical data from the region with numerical simulation
results. We find that the initial subduction of North Sulawesi must rely
on horizontal forces, while the trench retreat depends on the negative
buoyancy of the oceanic lithosphere. Furthermore, less space available
for subduction leads to lower mantle flow caused by subduction and
slower trench retreat. These new dynamical constraints indicate that the
negative buoyancy of the oceanic plate is the key factor for subduction
and trench retreat, even though the subduction initiation was induced.