| 松辽盆地地壳精细结构研究 |
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| 引用本文： | 况春利,张瑞青,陈成锋,刘嘉栋.松辽盆地地壳精细结构研究[J].地震学报,2022,44(4):555-566. |
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| 作者姓名： | 况春利 张瑞青 陈成锋 刘嘉栋 |
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| 作者单位： | 1.中国北京 100081 中国地震局地球物理研究所 |
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| 基金项目： | 国家自然科学基金（41874073，U1839210）资助 |
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| 摘 要： | 基于东北地区已有的宽频带流动台阵远震数据，利用波场延拓和分解的H-β网格搜索法，对松辽盆地的沉积层及地壳结构进行了深入分析。结果显示:松辽盆地的沉积层厚度为0.2—2.5 km，整体呈现中央坳陷区厚、边缘薄且西南地区最薄的分布特征；研究区地壳较薄，厚度介于24—34 km之间，其横向变化特征与沉积层厚度分布具有一定的对应性。依据沉积层和地壳的厚度计算了地壳伸展系数，其平均值接近于以往接收函数研究估测的岩石圈伸展因子。因此，本文推测松辽盆地在伸展构造过程中，其地壳和岩石圈的减薄以纯剪切模式为主。此外，松辽盆地具有较高的地壳平均波速比vP/vS，暗示盆地下方岩石圈地幔的减薄过程中可能存在岩浆的底侵作用。
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| 关 键 词： | 松辽盆地 H-β方法 沉积层厚度 地壳结构 波速比 |
| 收稿时间： | 2021-06-10 |
High-resolution crustal structure in the Songliao basin |
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| Affiliation: | 1.Institute of Geophysics，China Earthquake Administration，Beijing 100081，China2.Key Laboratory of Seismic Observation and Geophysical Imaging，China Earthquake Administration，Beijing 100081，China |
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| Abstract: | High-resolution shallow crustal structure beneath the Songliao basin of Northeast （NE） China has obvious economic and scientific significance. To constrain the sediment and crustal structure of the Songliao basin, H-β grid search method based on wavefield downward continuation and decomposition is used with teleseismic data recorded from portable broadband seismic arrays in the NE China. The results show that the estimated sediment thickness is 0.2?2.5 km, and becomes thinner from the central depression toward the margin of the basin, with the thinnest sediment in the southwestern region. The crustal thickness varies from 24 km to 34 km, and its lateral variation correlates with the distribution of sedimentary thicknesses to a certain extent. The crustal stretching factor is calculated from the sedimentary and crustal thicknesses, with an average close to the lithospheric stretching estimation from previous receiver function studies. Thus, we infer that the thinning of the crust and lithosphere is dominated by pure shear mode during the extensional process of the Songliao basin. Moreover, the Songliao basin has a high crustal vP/vS ratio, indicating possible magmatic underplating during the lithospheric extension beneath the Songliao basin. |
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