| 拉萨地体内低速异常成因的探讨--壳内局部熔融的地震层析证据 |
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| 关键词:Tibetan plateau seismic tomography velocity partial melting |
| 基金项目:国土资源重点基础研究专项（编号：20001010） |
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| 摘要: |
| Interpretation of the Low Velocity Anomalies in the Lhasa Terrain:Tomographic Evidence for Partial Melting in the Crust |
| The low velocity distribution pattern at the depths of 15～90 km in Lhasa terrain is well imaged through tomographic ana-lysis of seismic body waves acquired in southern Tibet. Based on a study of the velocity structure and the approximate Poisson′s ratio obtained, it is shown that the low velocity body in Lhasa terrain is correlated with partial melting in the crust. The partial melting is caused by the heat derived from subduction and crust shortening rather than by the mantle material intrusion. According to σvalue distribution, the authors hold that the low velocity body in mid-low crust east of Lhasa tends to extend eastward. The partial melting is restricted to a range of 15～35 km in depth. From the tiny time delay in SKS splitting in the area, it is inferred that the partial mel-ting may not exist in the mantle due to the lack of enough heating for the reorientation of anisotropic minerals. This adds to the evidence for the presence of partial melting only in the crust instead of in the mantle in this area. |
| XUE Guang-qi,WANG You-xue,SU He-ping.2005.Interpretation of the Low Velocity Anomalies in the Lhasa Terrain:Tomographic Evidence for Partial Melting in the Crust[J].Acta Geoscientica Sinica,26(5):411-415. |
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