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利用接收函数方法对横跨秦岭造山带、渭河地堑及鄂尔多斯块体的15个地震观测台站下方的地壳结构进行研究分析,结果表明三种不同类型(造山带型、拉张盆地型和稳定克拉通型)的构造单元的地壳结构和物质组成存在明显的差异.秦岭北缘平均地壳厚度为37.8 km,泊松比为0.247,相对偏低的泊松比表明地壳物质长英质组分增加.鄂尔多斯块体南缘平均地壳厚度为39.2 km,泊松比为0.265,偏高的泊松比与鄂尔多斯下方古老的铁镁质结晶基底以及浅部沉积有关.通过接收函数正演计算表明低速的、厚度较大的松散沉积层对Mohorovi i不连续面(Moho)的震相具有较大影响,是渭河地堑内部台站的接收函数Moho转换震相不清楚的主要原因.S波速度结构反演结果表明渭河地堑上覆松散沉积层,其厚度约为4~8 km,该沉积层使得位于渭河地堑内台站的接收函数Moho震相复杂.另外渭河地堑下方中下地壳位置存在一高速区域,该高速体可能与渭河断裂系统的活动有关.
The crustal structure below 15 seismic observation stations across the Qinling orogenic belt, Weihe Graben and Ordos blocks was studied by using the receiver function method. The results show that the crustal structures beneath the three different types (orogenic belt, pull-out basin type and stability Cratonic) tectonic units have obvious differences in crustal structure and material composition.The average crustal thickness in the northern Qinling Mountains is 37.8 km, Poisson’s ratio is 0.247, and the relatively low Poisson’s ratio indicates that the crustal material has an increase in long-quartzites The average crustal thickness at the southern margin of Ordos block is 39.2 km and the Poisson’s ratio is 0.265.The high Poisson’s ratio is related to the ancient mafic crystallization basement and shallow sediment beneath Ordos.The forward calculation of receiver function shows that low velocity , And the thicker loose sediments have a great influence on the seismic facies of the Mohorovi i discontinuity (Moho), which is the main reason for the unclear Moho transition of the receiver function within the Weihe graben station. The results show that the Weihe graben overlaps the loose sedimentary layer and has a thickness of about 4 ~ 8 km. This sedimentary layer makes the Moho seismic facies at the stations within the Weihe graben complex. In addition, the lower part of the Weihe graben In the presence of a high-speed position of the crust region, the high velocity may be related to activities Weihe fault system.