Abstract

To explore the dynamic mechanism of continental rifting within a convergent setting, we determine the first P wave radial anisotropic tomography beneath the Woodlark rift in southeastern Papua New Guinea, which develops within the obliquely colliding zone between the Australian and southwest Pacific plates. The rift zone is depicted as localized low-velocity anomalies with positive radial anisotropy, which rules out a dominant role of active mantle upwelling in promoting the rift development and favors passive rifting with decompression melting as main processes. Downwelling slab relics in the upper mantle bounding the rift zone are revealed based on observed high-velocity anomalies and negative radial anisotropy, which may contribute to the ultra-high pressure rock exhumations and rift initiation. Our observations thus indicate that the Woodlark rift follows a passive model and is mainly driven by slab pull from the northward subduction of the Solomon plate.

Department(s)

Geosciences and Geological and Petroleum Engineering

Comments

This study was funded by the National Natural Science Foundation of China (grant 42074052) and partially supported by the United States National Science Foundation (grant 1919789), the Alexan-der von Humboldt foundation, and Japan Society for the Promotion of Science (grant 19H01996).

Keywords and Phrases

Decompression Melting; Radial Anisotropy; Slab Downwelling; Slab-Pull; Ultra-High Pressure Rock; Woodlark Rift

International Standard Serial Number (ISSN)

1944-8007; 0094-8276

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2022 American Geophysical Union (AGU), All rights reserved.

Publication Date

16 Mar 2022

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