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为了深入认识与理解南北地震带北段和蒙古中部大陆强震孕育与发生的深部构造环境,在南北纵贯蒙古国全境的苏赫巴托尔—乌兰巴托—达兰扎达嘎德剖面上开展了大规模重磁测量及岩石样品采集。笔者系统地分析与总结了剖面上585块岩石样品的密度、磁化率和天然剩余磁化强度等物性参数。结果表明,整个剖面以火成岩为主,沉积岩为辅,仅有少量变质岩出露,且各岩石大类、类和亚类以及各年代地层之间,均存在着不同程度的密度与磁性差异。火成岩磁化率和天然剩余磁化强度分别具有3~5个数量级差异,密度变化范围较大;而沉积岩磁化率和天然剩余磁化强度相对较弱。一方面,物性差异为利用重磁测量开展剖面地壳结构的反演与研究奠定了基础;另一方面,这些物性参数为相关地球物理测量数据的反演与解释提供了重要约束。
In order to deeply understand and understand the deep tectonic environment in the north of the North-South Seismic Belt and the strong earthquakes in the middle of Mongolia, Sukhbaatar-Ulan Bator-Darlan Zadag Large-scale gravity and magnetic measurements and rock sample acquisition were carried out in the section. The author systematically analyzed and summarized the physical properties such as density, magnetic susceptibility and natural residual magnetization of 585 rock samples in the section. The results show that the whole section is mainly composed of igneous rocks, complemented by sedimentary rocks, and only a few of metamorphic rocks are exposed. There are different degrees of density and magnetic differences among various rock types, sub-classes and strata. The susceptibility of igneous rocks and natural residual magnetization have 3 ~ 5 orders of magnitude difference, respectively, and the range of density changes is relatively large. However, the susceptibility of sedimentary rocks and natural residual magnetization are relatively weak. On the one hand, the physical differences provide the basis for the inversion and study of the crustal structures using gravity and magnetic measurements; on the other hand, these physical parameters provide important constraints for the inversion and interpretation of relevant geophysical survey data.