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2011年8月至2013年7月中国地震局地球物理研究所与蒙古科学院天文与地球物理研究中心在蒙古中南部区域布设了宽频带流动地震台阵,这为开展远东地区深部结构的精细探测提供了有利的数据基础.利用台阵记录的远震地震事件,采用P波接收函数的H——(-κ)叠加分析和共转换点(CCP)叠加方法获得了台站下方的地壳厚度及平均波速比.结果显示研究区的地壳厚度介于39 km至45 km之间.整体上Moho面埋深从西北往东南方向逐渐变浅.在蒙古主线性构造两侧地壳厚度呈现区域性变化特征,东南部地区地壳厚度较薄,约为39 km,而西北部地区地壳较厚,达45 km,为此推测蒙古主构造线可能是地壳的一个陡变带.此外,研究地区地壳的平均波速比值(V_p/V_s)在1.70到1.79之间,均值为1.75,低于全球大陆的平均值1.78,这可能暗示着该区其地壳是缺少铁镁质的.研究还发现测线的西北与东南地区其地壳波速比值较高,推测是古生代铁镁质地壳的残留或是新生代岩浆底侵的反映.
From August 2011 to July 2013, the Institute of Geophysics, the Chinese Seismological Bureau and the Astronomy and Geophysics Research Center of the Mongolian Academy of Sciences have deployed broad-band mobile seismic arrays in the central-southern region of Mongolia, providing the fine detection of deep structures in the Far East A good data foundation is obtained.Using the teleseismic events recorded by the array, the thickness and average crustal thickness beneath the station are obtained by using H - (- κ) overlay analysis and CCP stacking method of the P wave receiving function Wave velocity ratio.The results show that the thickness of the crust in the study area ranges from 39 km to 45 km.The overall depth of the Moho surface becomes gradually shallow from northwest to southeast.The crustal thickness on both sides of the main linear structure in Mongolia shows a regional variation, In the southeastern part of the world, the crustal thickness is relatively thin, about 39 km, whereas the crust in the northwestern part is relatively thick at 45 km, suggesting that the main tectonic line in Mongolia may be a steep change in the crust. In addition, the average crustal ratio ( V_p / V_s) ranged from 1.70 to 1.79 with a mean value of 1.75, lower than the global average of 1.78, which may suggest that the crust in the area is deficient in ferromagnetics.The study also found that the northwest and southwestern The higher crustal wave velocity ratio is presumed to be a reflection of Paleozoic Fe-Mg crustal remnant or Cenozoic magma underplating.