青藏高原羌塘盆地中央隆起近地表速度结构的初至波层析成像试验

    First arrival seismic tomographic imaging test of the near-surface velocity structure of central uplift in the Qiangtang basin, Qinghai-Tibet Plateau

    • 摘要: 利用2条衔接并横过青藏高原羌塘盆地中央隆起的反射地震剖面探测数据,进行了初至波层析成像试验,以揭示羌塘中央隆起的表层结构特征。研究结果表明,大量的反射地震单炮记录初至清晰,长排列接收丰富了浅表构造趋势特征的信息,层析走时射线密度随地下构造的复杂程度而变化。层析反演得到的速度结构显示了高速层起伏剧烈的变化特征,其厚度与地表出露地层的年代负相关。深反射地震初至波走时层析成像可以提供丰富的地壳近地表结构信息。

       

      Abstract: In 2007 and 2008 two reflection seismic profiles that linking up and crossing the central uplift of the Qiangtang basin were acquired in Tibetan Plateau. The aim of writing this paper is to take advantage of these probe data and test the first arrival tomographic method to imaging the near-surface velocity structure of the central uplift in the Qiangtang. The results indicate that the first arrivals are clear in the recordings of high dynamite shots, and the detailed shallow structure trend emerges at long array receivers. The tomographic travel-rays assemble where the structure is complex underground. The tomographic image reveals the undulate character of the high velocity structure both vertical and horizontal. And its thickness has negative correlation with the age of the outcrop. All the research testifies that the first arrival seismic tomographic imaging method can provide more detailed near-surface velocity structure information.

       

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