Joint Geodynamic‐Geophysical Inversion Suggests Passive Subduction and Accretion of the Ontong Java Plateau

• Published in: Geophysical research letters 2022-12, Vol.49 (23), p.n/a
• Main Authors: Dong, Hao, Dai, Liming, Liu, Lijun, Jiang, Xiaodian, Li, Sanzhong, Gong, Wei, Wang, Liangliang, Wang, Di, Li, Zhong‐Hai, Yu, Shengyao
• Format: Article
• Language: English
• Subjects: Accretion; Bouguer gravity; Concretions; Crustal structure; Crusts; Deposition; Dynamics; Geophysics; Gravity; Island arcs; joint geodynamic‐geophysical inversion; Lithosphere; numerical modeling; Ocean models; Oceanic plateau; Ontong Java Plateau; Plateaus; Plates; Plates (tectonics); Seismic data; Seismological data; Subduction; Subduction (geology); Topography
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL100744

In this study, we for the first time applied a joint geodynamic‐geophysical inversion approach to oceanic plateau subduction models, and compared the subduction style and corresponding topography and Bouguer gravity of two representative subduction scenarios with passive or active collision. We showed that the case of passive collision of the Ontong Java Plateau (OJP) crust better explains the topography, gravity, and seismic data than the active collision scenario. This implies that the OJP did not control the regional dynamics during the collisional process. We conclude that previous studies may have overestimated the role of the OJP in triggering subduction initiation, subduction polarity reversal, and even Pacific Plate rotation. Plain Language Summary The effect of the Ontong Java Plateau (OJP), the largest oceanic plateau on Earth, on subduction dynamics remains controversial. Proposed models for the evolution of the OJP range from dominantly “soft docking” that generates shallow subduction and little impact on nearby regions, to strong and active collision that results in deep plateau subduction, extensive accretion, subduction polarity reversal, and even major plate reorganization. Determining the subduction depth and accretion volume of OJP is the key to resolving this dispute. In the former, the oceanic plateau undergoes shallow subduction with its upper and middle crusts slightly accreted into the island arc, leading to relatively low topography and a flat Bouguer gravity profile, consistent with observation. The latter case leads to deep subduction of the plateau lithosphere, resulting in high topography, low Bouguer gravity, and crustal structures that all violate observation. Key Points The joint geodynamic‐geophysical inversion approach can help distinguish ambiguous dynamic behaviors of oceanic plateau subduction The Bouguer gravity and other observations of Ontong Java Plateau (OJP) favor the passive collision model over the active collision model OJP should have played a passive role in the collision process, implying the overestimation in previous studies