科研之友
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摘要
We picked 10301 S wave relative traveltime residuals from the teleseismic waveform data by waveform correlation method. The teleseismic waveform data were recorded by the temporary and permanent seismic networks in Northeast China from June 2009 to May 2011, the total number of the station is 234. We imaged the S-wave velocity structure beneath Northeast China down to 800 km depth by two ray traveltime tomography methods. The S-wave velocity anomaly structures are partly restricted by the two different tomography results in this area. Most parts of the S wave results are similar to the previous P wave results: There is a high-velocity anomaly beneath the Changbaishan volcano, maybe this anomaly is the Pacific Plate, which subducted under the Eurasian Plate. Because of the local depressing of the plate, the shape of the plate doesn't appear as an obvious slab. There are low-velocity anomalies beneath the Changbaishan volcano, A'ershan volcano and Wudalianchi volcano. The low-velocity anomalies under the Changbaishan and A'ershan volcano extend down to the near area of mantle transition zone, while the low-velocity anomaly under the Wudalianchi volcano extends down to about 200 km depth, which may indicate that Changbaishan and A'ershan volcano have some relationship with the low-velocity anomalies under them, and the different depths of the low-velocity anomalies represent the different origin of the Wudalianchi volcano. There is a mainly high-velocity zone with a mixture high- and low-velocity distribution character beneath the Songliao Basin area. The mixture character suggests that the lithospheric mantle may have suffered destruction and transformation, and lithospheric delamination may have occurred and greatly affected the Songliao Basin. The low-velocity anomaly beneath the southern part of Songliao Basin area is connected to the low-velocity anomalies beneath the Changbaishan and A'ershan volcano, which may be a upwelling material channel from the lower mantle. We show the upper mantle S wave anomaly structure of Northeast China, which is similar to the P wave result but from another perspective, and provides an important constraint on our understanding of this area.
- 出版日期2014-1
- 单位中国地震局
