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- Title
The velocity structure of the Longnan seamount in the Southwest Sub-basin, South China Sea.
- Authors
Zhang, Jie; Li, Jiabiao; Ruan, Aiguo; Ding, Weiwei; Yu, Zhiteng; Niu, Xiongwei; Wang, Wei
- Abstract
Seamounts comprise up to 25% of the seafloor (Gilbert, 2004) and most of them are volcanic origin (e.g., Smith & Cann, 1992). Submarine volcanism has resulted in the large vertical and horizontal displacements (e.g., Staudigel & Clague, 2010) and the emplacement of seamounts(e.g. Contreras-Reyes et al., 2010). However, the internal structure and evolution of the seamounts remains unclear, which limits the understanding of post-spreading magmatism in the South China Sea. We conducted a seismic refraction survey over an axial seamount (Longnan Seamount) in the Southwest Sub-basin, South China Sea in 2010. Results show that the post-spreading axial seamount was mainly formed by an extrusive process. The upper-crustal velocities (2.9–4.7 km/s) observed at the seamount are significantly lower than those of normal oceanic crust (~4.7 km/s), suggesting explosive materials and increased porosities in the basalts. The lack of clear Moho reflections and a low-velocity upper mantle (7.7–7.8 km/s) may indicate mantle serpentinization beneath the seamount(e.g. Delescluse et al., 2015). Compared with the Huangyan and Zhenbei seamounts in the East Sub-basin, the Longnan seamount in the Southwest Sub-basin is characterized by the crustal accretion occurring in layer 2 only, which may be result from the difference tectonic characteristics. The proposed model for post-spreading seamount formation is marked by an episodic process and controlled both by tectonics and by magmatism.This research was granted by the National Program on Global Change and Air–Sea Interaction, SOA (GASI-GEOGE-01), the National Natural Science Foundation of China (41706044, 91628301, 91028006, 91228205)
- Subjects
CHINA; OCEANIC crust; OCEAN-atmosphere interaction; SEISMIC surveys; VELOCITY; SEAMOUNTS; CONTINENTS
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article