The study of mantle transition-zone shows that velocity discontinuities of 410km and 660km were caused by phase-change. Subduction through these two discontinuities will change the depth of the discontinuities. A flat subduction slab lying on the 660km was observed in North-East China subduction-zone by seismic imaging, and a deeper 660km discontinuity was reported by receiver function studies. But the receiver function results in Tibetan collocation zone does not show any significant elevation or depression of the discontinuities. To exam whether there is no subduction-slab through the discontinuities in these areas, or we have not observed the discontinuity caused by subduction-slab, we carry out a thermal simulation in the area, and compute the possible elevation and depression of the discontinuities. We have considered subduction models with different angles and a model the whole Tibetan plateau was thicken by Indian lithosphere. When we only consider the Olivine-Spinel phase change as the cause of 410km velocity discontinuity, and Olivine-Perovskite phase change as the cause of the 660km velocity discontinuity, our result shows that the subduction similar to our models will change the depth of discontinuities significantly, and could be observed by seismic receiver function method. According to our results and the receiver function results, we tend to support the opinion that there does not exist deep subduction slab in Southern Tibet, and the subduction may go further north.
|Number of pages||7|
|Journal||Zhongguo ke xue yuan yan jiu sheng yuan xue bao = Journal of the Graduate School of the Chinese Academy of Sciences|
|Publication status||Published - 2009|
- FD method
- Thermal simulation