阴山造山带及鄂尔多斯盆地北部地区上地壳的地震波属性结构及岩性推断

Structure of the seismic wave property and lithology deduction of the upper crust beneath the Yinshan orogenic belt and the northern Ordos block

通过对跨越阴山造山带及鄂尔多斯块体北部的长剖面进行人工源宽角反射/折射地震探测,采集了地震记录中Sg震相的走时,并进行了反演,求得了沿剖面辖区的上地壳S波速度结构模型.同时利用P波和S波速度结构求取了剖面沿线上地壳中泊松比的分布.根据所得到的地震波场属性与结构,结合该区已有的地质研究成果和钻孔信息,推断了剖面沿线不同构造块体的物性分布特征.研究结果表明:沿该剖面自南向北包括鄂尔多斯块体北部、呼包凹陷盆地、阴山造山带和苏尼特褶皱系等四大不同构造块体,它们无论是在地震波速度结构、泊松比分布特征以及岩性构造特征等方面均呈现出明显的差异.在上述研究的基础上,探讨了沿剖面各构造块体的矿产资源以及油、气、煤等能源的赋存及勘探开发前景.

A deep seismic wide-angle reflection/refraction sounding profile was set across the Yinshan orogenic belt and the northern Ordos basin. Using the travel time data obtained from the seismic sounding record, we determined the S wave velocity structure of the upper crust beneath the profile. Meanwhile, we calculated the Poisson ratio distribution along the profile using both the P wave and S wave velocity data. Based on the seismic wave field properties and structure, as well as the geological research result and the borehole data, the lithological distribution beneath the profile was deducted. The research result suggests that this profile could be divided into four major parts, which are the northern part of the Ordos basin, the Hubao depression basin, Yinshan orogenic belt and the Sunit fold system. There exist different characteristics in velocity structure, Poisson ratio distribution, and lithological composition in these four tectonic units. On basis of all the research mentioned above, we discussed the occurrence and exploitation prospects of mineral resources, coal, oil and gas energy in different tectonic units along the profile.