Mapping the Upper Mantle Discontinuities beneath North China Craton from Common Conversion Points Method with Teleseismic Receiver Functions
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摘要: 上地幔过渡带的结构形态对于研究上覆岩石圈的构造环境有十分重要的意义。本文通过对横跨华北克拉通中东部的一条北西向的测线L上分布的35个宽频带台站记录的远震数据进行接收函数的计算和共转换点叠加成像,得到了测线下方上地幔过渡带的结构。成像结果表明:华北克拉通的三个陆块处于不同的构造环境,西部陆块较为稳定,中部造山带位于地幔对流较强的构造环境内,而东部陆块由于受到太平洋俯冲板块的影响,所处环境温度较低,说明中部造山带内的裂陷盆地在形成过程中,受到地幔对流作用的影响较大,而东部陆块内的新生代裂陷盆地在形成过程中,可能主要是受到右旋拉张力的作用,两者的形成主要动力或有不同。Abstract: It is very important to study the structure of upper mantle transition zone to understand the tectonic environment of the lithosphere above.In this paper,we calculate the P receiver functions from the teleseismic events recorded by 35 stations in a line across the North China Craton(NCC),and then mapping the upper mantle structure from the method of common conversion points.The result shows that:the three blocks of the North China Craton stay in different tectonic environment,the western block stay in a stable environment,while the trans-North China oragan in a strong mantle convection circulation environment.The subducted pacific slab under the eastern block formed a relative low temperature under the eastern NCC.So the mantle convection plays an important role in the formation of the Shanxi fault depression zone by contrast with the dextral rotation which is the mainly force of the Huabei fault depression zone.
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