Whole‐Mantle Tomography of Southeast Asia: New Insight Into Plumes and Slabs. Issue 11 (25th November 2022)

• Record Type: Journal Article
• Authors: Toyokuni, Genti; Zhao, Dapeng; Kurata, Kenkichi
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-25
• Subjects: Southeast Asia -- seismic tomography -- whole mantle -- Hainan hotspot -- plate subduction -- hot mantle upwelling; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2022JB024298
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: We present detailed 3‐D images of the whole mantle P wave velocity structure beneath Southeast Asia and surrounding regions. The results are obtained by applying an improved method of global seismic tomography to invert ∼8 million P, pP, PP, PcP, and Pdiff arrival times from 23, 587 earthquakes recorded at 14, 136 stations distributed all over the world. Our tomographic model reveals a continuous, thin low‐velocity (low‐ V ) zone from the surface to the core‐mantle boundary beneath the Hainan hotspot, which may reflect the Hainan plume that exists in the whole mantle. Beneath the Australian slab that has subducted into the lower mantle, a strong low‐ V anomaly is detected, which may reflect subslab hot mantle upwelling (SHMU) due to return flow of the slab subduction. Our model also clearly reveals the subducted slabs in the upper mantle and slab remnants in the lower mantle. In particular, a hole in the subducting Australian slab is revealed at depths of 280–460 km beneath eastern Java. The low‐ V anomaly in the mantle wedge above the Australian slab is connected with the SHMU through the slab hole, suggesting that mixture of the island arc magma and the SHMU may have caused huge eruptions of the Tambora and Rinjani volcanoes in eastern Java. Plain Language Summary: Southeast Asia is surrounded by plate subduction zones, and very intense seismic and volcanic activities have been occurring there. Volcanic activity originating from the deep Earth, attributed to the Hainan hotspot, also takes place. It is known that seafloor spreading and subduction have repeated in the past, and the relationship between the slabs subducted into the deep mantle and the plate movement on the surface is an important key to understanding the evolution history of this region. In this study, we apply an improved method of global seismic tomography to investigate the whole mantle 3‐D P wave velocity structure beneath SE Asia. For the first time, a continuous whole‐mantle plume is revealed beneath the Hainan hotspot with its root at the core‐mantle boundary. Hot mantle upwellings above and below the subducting Australian slab are connected through a slab hole at depths of 280–460 km beneath eastern Java. The mixture of those hot mantle materials might have caused huge eruptions of the Tambora and Rinjani volcanoes in eastern Java. Key Points: A novel high‐resolution P wave tomographic model of the entire mantle beneath Southeast Asia is obtained Our tomography reveals a continuous whole‐mantle plume beneath the Hainan hotspot rising from the core‐mantle boundary A strong low‐velocity anomaly exists beneath the Australian slab, which may reflect subduction‐induced hot mantle upwelling