A Slab Window Beneath North Sumatra Revealed by P-Wave Mantle Tomography

Hu, Hao1,2; Zhao, Dapeng3; Lin, Jian2,4,5,6; Pilia, Simone7

2023-06-01

10.1029/2022JB025976

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   影响因子和分区

2169-9313

2169-9356

["Passive seismic studies have suggested that slab tearing occurs beneath North Sumatra, albeit the slab morphology is somewhat poorly constrained. The lack of resolution on the slab means that the presence of a tear has not been validated, and that the main factors responsible for slab tearing are hard to discern. We use a large seismic data set to determine a new 3-D high-resolution tomographic model of the crust and upper mantle beneath North Sumatra, which reveals a well-defined low-velocity channel that cuts across the subducting slab through a cavity. This feature cannot be reconciled with a tear in the slab, as previously suggested. Our relocated earthquakes exhibit a protruding cluster of seismicity along the subducted Investigator Fracture Zone, indicating that the high reliefs of the Investigator Fracture Zone possibly enhance the coupling between the subducted slab and the overriding plate. Shear stress resulting from the differential coupling in the slab may have created an area of mechanical weakness in correspondence of the fossil-spreading ridges, which eventually led to the formation of a slab window. This window allows the exchange of mantle material from the subslab region up to the Toba volcano. We propose that the previously damaged parts (e.g., fracture zones and spreading centers) of the oceanic plate could help promote the growth of a slab window.","Plain Language Summary Seafloor fabrics are damaged traces of the oceanic plate, which may break again during subduction, leading to tearing, slab window or full slab detachment. Slab breaking is a pivotal process in the tectonic evolution of the lithosphere and underlying mantle, and can lead to complexities in slab deformation and mantle dynamics, new intraplate magmatism, and rapid uplift. Slab tearing in the subducted Indo-Australian oceanic lithosphere beneath North Sumatra has been suggested by studies of seismicity and 3-D seismic tomography. However, the crucial contributing factor to the initiation of slab breaking is a matter of debate. Our high-resolution tomographic results reveal the fine crustal and upper-mantle structure under North Sumatra, showing a very low P-wave velocity hole cutting through the subducting slab. According to the location of seafloor fabric structures (e.g., fracture zones and fossil ridges in the Wharton basin) and the corresponding low-velocity hole in our tomographic images, we suggest that the subducted seafloor fabrics are responsible for the slab window of the subducting Indo-Australian plate beneath North Sumatra. We propose that the weak compartments of fossil-spreading ridge and the obstructed Investigator Fracture Zone are keys for the onset of slab breaking."]

slab window seafloor fabrics P-wave tomography North Sumatra

SCI

英语

NI论文

通讯

National Natural Science Foundation of China["41890813","42106068"] ; China Postdoctoral Science Foundation[2021M691412] ; Japan Society for the Promotion of Science[19H01996] ; Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory[GML2019ZD0205] ; Chinese Academy of Sciences["Y4SL021001","QYZDY-SSWDQC005","133244KYSB20180029","131551KYSB20200021","ISEE2021PY03"] ; Guangdong Provincial Research and Development Program in Key Areas[2020B1111520001]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:001022761300001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.Zhejiang Univ Water Resources & Elect Power, Sch Geomat & Municipal Engn, Hangzhou, Peoples R China
2.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
3.Tohoku Univ, Grad Sch Sci, Dept Geophys, Sendai, Japan
4.Southern Marine Sci & Engn Guangdong Lab Guangzhou, Guangzhou, Peoples R China
5.Chinese Acad Sci, South China Sea Inst Oceanol, Innovat Acad South China Sea Ecol & Environm Engn, Key Lab Ocean & Marginal Sea Geol, Guangzhou, Peoples R China
6.Woods Hole Oceanog Inst, Dept Geol & Geophys, Falmouth, MA USA
7.King Fahd Univ Petr & Minerals, Coll Petr Engn & Geosci, Dhahran, Saudi Arabia

Hu, Hao,Zhao, Dapeng,Lin, Jian,et al. A Slab Window Beneath North Sumatra Revealed by P-Wave Mantle Tomography[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2023,128(6).

Hu, Hao,Zhao, Dapeng,Lin, Jian,&Pilia, Simone.(2023).A Slab Window Beneath North Sumatra Revealed by P-Wave Mantle Tomography.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,128(6).

Hu, Hao,et al."A Slab Window Beneath North Sumatra Revealed by P-Wave Mantle Tomography".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 128.6(2023).