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- Title
Seismic evidence for melt-rich lithosphere-asthenosphere boundary beneath young slab at Cascadia.
- Authors
Wang, Xin; Chen, Ling; Wang, Kelin; Chen, Qi-Fu; Zhan, Zhongwen; Yang, Jianfeng
- Abstract
The Lithosphere-Asthenosphere Boundary (LAB) beneath oceanic plates is generally imaged as a sharp seismic velocity reduction, suggesting the presence of partial melts. However, the fate of a melt-rich LAB is unclear after these plates descend into the mantle at subduction zones. Recent geophysical studies suggest its persistence with down-going old and cold slabs, but whether or not it is commonly present remains unclear, especially for young and warm slabs such as in the Cascadia subduction zone. Here we provide evidence for its presence at Cascadia in the form of a large (9.8 ± 1.5 % ) decrease in shear-wave velocity over a very small (<3 km) depth interval. Similarly large and sharp seismic velocity reduction at the bottom of both old and young slabs, as well as along the base of oceanic plates before subduction, possibly represents widespread presence of melts. The melt-rich sub-slab LAB may strongly influence subduction dynamics and viscoelastic earthquake cycles. This study provides seismic evidence for the presence of partial melts along the base of Cascadia's subducting slab, with implications to lithosphere-asthenosphere decoupling that potentially influences subduction dynamics and earthquake cycles.
- Subjects
SUBDUCTION; SUBDUCTION zones; SEISMIC wave velocity; IRON &; steel plates; EARTHQUAKES; IMAGING systems in seismology
- Publication
Nature Communications, 2024, Vol 15, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-024-47887-0