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Journal Articles Geophysical Research Letters Year : 2015

Seismic observation of an extremely magmatic accretion at the ultraslow spreading Southwest Indian Ridge

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Jiabiao Li
  • Function : Author
Yongshun John Chen
  • Function : Author
Aiguo Ruan
  • Function : Author
Xuelin Qiu
  • Function : Author
Minghui Zhao
  • Function : Author
Xianguang Wang
  • Function : Author
Xiongwei Niu
  • Function : Author
Jianyu Ni
  • Function : Author
Jiazheng Zhang
  • Function : Author

Abstract

The oceanic crust is formed by a combination of magmatic and tectonic processes at mid-ocean spreading centers. Under ultraslow spreading environment, however, observations of thin crust and mantle-derived peridotites on the seafloor suggest that a large portion of crust is formed mainly by tectonic processes, with little or absence of magmatism. Using three-dimensional seismic tomography at an ultraslow spreading Southwest Indian Ridge segment containing a central volcano at 50°28'E, here we report the presence of an extremely magmatic accretion of the oceanic crust. Our results reveal a low-velocity anomaly (-0.6 km/s) in the lower crust beneath the central volcano, suggesting the presence of partial melt, which is accompanied by an unusually thick crust (~9.5 km). We also observe a strong along-axis variation in crustal thickness from 9.5 to 4 km within 30-50 km distance, requiring a highly focused melt delivery from the mantle. We conclude that the extremely magmatic accretion is due to localized melt flow toward the central volcano, which was enhanced by the significant along-axis variation in lithosphere thickness at the ultraslow spreading Southwest Indian Ridge.
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insu-03579979 , version 1 (18-02-2022)

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Jiabiao Li, Hanchao Jian, Yongshun John Chen, Satish C. Singh, Aiguo Ruan, et al.. Seismic observation of an extremely magmatic accretion at the ultraslow spreading Southwest Indian Ridge. Geophysical Research Letters, 2015, 42, pp.2656-2663. ⟨10.1002/2014GL062521⟩. ⟨insu-03579979⟩
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