林吉焱, 段永红. 2016: 海原构造区及其周缘上部地壳结构研究. 地震学报, 38(2): 179-187. DOI: 10.11939/jass.2016.02.003
引用本文: 林吉焱, 段永红. 2016: 海原构造区及其周缘上部地壳结构研究. 地震学报, 38(2): 179-187. DOI: 10.11939/jass.2016.02.003
Lin Jiyan, Duan Yonghong. 2016: Upper crustal structure of Haiyuan tectonic zone and its surrounding areas. Acta Seismologica Sinica, 38(2): 179-187. DOI: 10.11939/jass.2016.02.003
Citation: Lin Jiyan, Duan Yonghong. 2016: Upper crustal structure of Haiyuan tectonic zone and its surrounding areas. Acta Seismologica Sinica, 38(2): 179-187. DOI: 10.11939/jass.2016.02.003

海原构造区及其周缘上部地壳结构研究

Upper crustal structure of Haiyuan tectonic zone and its surrounding areas

  • 摘要: 基于甘肃省夏河县—陕西省靖边县剖面的8次人工地震初至波数据, 利用有限差分走时方法反演得到了沿该剖面长约650 km的上部地壳速度结构和结晶基底的深度分布. 反演结果显示: 海原构造区西侧的西秦岭—祁连山褶皱区上部地壳的横向非均匀性明显, 基底深度从1 km到5 km不等, 反映了褶皱区改造变形强烈的构造特征; 其东侧的鄂尔多斯盆地基底深度约为5—6 km, 其速度均匀、 稳定, 上地壳呈弱速度梯度特征; 海原构造区及海原弧形断裂带附近上部地壳的破坏变形最严重, 区内横向高低速相间分布. 综上可知, 海原构造区东西两侧上地壳结构的显著差异揭示了其结构复杂性的成因及其与地震活动性的关系.

     

    Abstract: By using the eight-shots of deep seismic sounding records from the Xiahe (Gansu Province) to Jingbian (Shaanxi Province) section, we get the upper crustal structure and basement depth of Haiyuan tectonic zone and its surrounding areas, which is a 650 km long profile. The result shows that, Qinling-Qilianshan folding zone in the west of Haiyuan tectonic zone has an obviously lateral heterogeneity in upper crust, the basement depth ranges from 1 to 5 km, which reveals that the zone has been destructed and deformed strongly. Whereas on the east side of Haiyuan tectonic zone, the Ordos block exhibits a homogeneous and stable upper crust, which has a 5-6 km depth crystalline basement and a relative low velocity gradient. Moreover, the upper crust of Haiyuan tectonic zone and the Haiyuan arcuate fault zone are the most strongly destructed and deformed areas along the profile. Therefore, the distinct difference in upper crust structure between the east and west side of Haiyuan tectonic zone reveals the cause of structural complexity and its relation with seismic activities.

     

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