A total of 10,586 P-to-S radial receiver functions recorded by 64 broadband seismic stations were utilized to image the 410 and 660 km discontinuities (d410 and d660, respectively) bordering the mantle transition zone (MTZ) beneath the Sumatra Island, the Malay Peninsula, and the western margin of the South China Sea. The d410 and d660 were imaged by stacking receiver functions in successive circular bins with a radius of 1°, after moveout corrections based on the 1-D IASP91 Earth model. The resulting apparent depths of the discontinuities exhibit significant and spatially systematic variations. The apparent depths of the d410 and d660 range from 382 to 459 km and 637 to 700 km with an average of 406 ± 13 and 670 ± 12 km, respectively, while the corresponding values for the MTZ thickness are 217 to 295 km and 261 ± 13 km. Underneath southern Sumatra and adjacent regions, the MTZ is characterized by an uplifted d410 and a depressed d660. While the former is probably caused by the low temperature anomaly, the latter is most likely related to a combination of the low temperature anomaly and dehydration associated with the subducted Australian Plate that has reached at least the d660. In contrast, an abnormally thin MTZ is imaged to the southwest of the Toba Caldera. This observation, when combined with results from previous seismic tomography studies, can be explained by advective thermal upwelling through a slab window.
F. Kong et al., "Slab Dehydration and Mantle Upwelling in the Vicinity of the Sumatra Subduction Zone: Evidence from Receiver Function Imaging of Mantle Transition Zone Discontinuities," Journal of Geophysical Research: Solid Earth, vol. 125, no. 9, Wiley, Sep 2020.
The definitive version is available at https://doi.org/10.1029/2020JB019381
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Australian Plate; Mantle Transition Zone; Slab Window; South China Sea; Sumatra; Toba Supervolcano
International Standard Serial Number (ISSN)
Article - Journal
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01 Sep 2020