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:
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.