【摘要】 利用小波的“变焦距”多分辨功能 ,提出了针对壳幔过渡带复杂波形的变尺度震相分析方法 ,将它与壳幔过渡带非均匀尺度的研究相联系 ,使得传统的震相识别由“静态”转变为“动态”并编写了相应的计算程序 .对玛沁—兰州—靖边地震测深剖面壳幔过渡带的Pm波形 ,利用复杂性系数法获得了沿剖面的 2个陆 -陆碰撞带 ,它们分别对应玛沁断裂和海原 8 5级强震区的位置 .利用变尺度震相分析方法得到了玛沁断裂和海原地震下方壳幔过渡带的多层Pm震相 .结果表明 ,海原地震下方的壳幔过渡带厚度约有 2 0km ,层状清晰 ,它至少由 3个高低速相间的层组成 ;玛沁断裂所对应的壳幔过渡带大约由 2个较薄的层组成 .这种分层和厚度的不同表明了鄂尔多斯地块和祁连地块的接触带、巴颜喀拉地块和柴达木地块的接触带由于陆 -陆碰撞的时期和相互作用的方式不同 ,因此在现今可分辨的壳幔过渡带结构非均匀尺度上存在明显差异 .更多还原

【Abstract】 Using "zoom" multi-resolution characteristics of wavelets, we developed a method of varying scale phase analysis used to complicated waveforms of crust-mantle transitional zone (CMTZ). The method is applied to the study of heterogeneous scale of CMTZ, making the conventional phase identification from "static" into "dynamic". On the basis of Pm waveform of CMTZ along Maqin-Lanzhou-Jingbian profile, two continent-continent collision zones were reveal with the complexity coefficient method. The two zones correspond to the Maqin fault and the region of M8.5 Haiyuan earthquake, respectively. The multi-layer Pm phase under the Maqin fault and Haiyuan earthquake was obtained with the varying scale phase analysis method. The result shows that CMTZ under Haiyuan earthquake is about 20km thick, with distinguishable layers. It consists at least of 3 layers of high and low velocity alternatively, whereas CMTZ corresponding to the Maqin fault is composed of 2 thin layers. This difference in stratification and thickness shows that the contact zone between Ordos block and Qilian block differs obviously from the contact zone between Bayanhar block and Qaidam block in the present distinguishable heterogeneous scale of CMTZ, because the continent-continent collisions happened at different times and the continents interacted in different ways.更多还原