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.
Y. Yu et al., "Continental Break-Up under a Convergent Setting: Insights from P Wave Radial Anisotropy Tomography of the Woodlark Rift in Papua New Guinea," Geophysical Research Letters, vol. 49, no. 5, article no. e2022GL098086, Wiley; American Geophysical Union, Mar 2022.
The definitive version is available at https://doi.org/10.1029/2022GL098086
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
decompression melting; radial anisotropy; slab downwelling; slab-pull; ultra-high pressure rock; Woodlark rift
International Standard Serial Number (ISSN)
Article - Journal
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16 Mar 2022