Crustal structure in the Yunnan region determined by modeling receiver functions
Crustal structure in the Yunnan region determined by modeling receiver functions
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发表时间：
2009
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通讯作者：
Liang Yong
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作者：
Liang Yong
为了研究云南及邻区的地壳结构，选取云南地震台网和CDSN记录的宽频带地震波形资料，采用地壳转换和多次波的网格搜索方法，假定地壳中P波速度为平均值，估算地壳厚度和Vp/Vs比值，并进行Telese-P波波形模拟，研究S波速度结构。结果表明，云南地区地壳厚度横向变化强烈，存在低速带和高Vp/Vs带，特别是滇西地区，这些都可能是中下地壳地壳流动的证据，是地壳增厚的原因之一。红河断裂带两侧的Vp/Vs和地壳厚度不同，结合其他地球物理研究成果，我们认为思茅板块和保山-腾冲板块都属于冈瓦纳板块。
We selected broadband teleseismic waveform data recorded by the Yunnan Seismic Network and CDSN to study the crustal structure in Yunnan and its adjacent region.The crustal thickness and Vp/Vs ratio are estimated by the grid-search method using crustal conversion and multiples,assuming an average P-wave velocity in the crust.Teleseismic P waveform modeling is carried out to investigate the S-wave velocity structure,assuming the fixed Vp/Vs value inferred from the grid-search method.The results from the two estimation techniques were consistent.Our results show strong lateral variations in crustal thickness in this area.Our results also indicate that there exist low velocity zones and high Vp/Vs beneath the Yunnan region,especially in western Yunnan.All these are the possible evidence of the crustal flow in middle-to-lower crust,which are responsible for the thickening of crust.The Vp/Vs and crustal thickness are different across the Red-river fault,which implies that the Red-river fault is one main boundary fault.Combining results from other geophysical investigations,we conclude that both the Simao terrane and Baoshan-Tengchong terrane belong to the Gondwana plate.