【摘要】 为了研究辽宁省海城7.3级地震发生的地质背景——辽南地区的地壳构造,根据已有的反映深部界面起伏的重力资料,以及本文提出的方法除去新生代沉积和浅部构造影响后的重力异常,用等效压缩质面方法计算莫霍界面深度。并采用密度差异的原理,从重力异常中分解出康拉界面的影响,从而求得康拉界面的深度。根据13条计算剖面的结果,给出辽南地区的康拉界面和莫霍界面的分布。根据莫霍界面的起伏,此地区大致可划分为三个部分。中部:为一北东向的上地幔隆起带,北低南高,一直向西南延伸入渤海。隆起的东南坡陡,西北坡缓,且呈台阶式次第下倾。在此大的构造背景上展布了一系列具有相当规模的次一级正、负构造。地壳厚度在隆起部分为31—32公里,但其东缘较薄,约为30公里左右。东南部:地壳厚度一般为34—35公里,最大可达38公里.西北部:地壳厚度向西北方向由34公里逐渐增至40公里左右。海城地震就发生在中部隆起带的较陡的东南坡上。 文中对有关的计算方法作了简要的介绍。并对一些问题进行了讨论。更多还原

【Abstract】 To study the crustal structure of the southern part of Liaoning Province, whichis the geological background of the occurrence of the Haicheng (海城) Earthquake,M=7.3. The available gravity data of the region and the method of "compressedmass plane" suggested in this paper were used to compute the depth of the MohorovicicDiscontinuity, from gravity anomalies after removing the effect of the superficialsedimentary layers and shallow geological structures. In addition, the principle of"density difference" was adopted to separate the effect of the Conrad Discontinuityfrom the gravity anomaly, in order to estimate the depth of the Conrad Discontinuity. The distribution of these two discontinuities in southern Liaoning Province wasobtained, basing on the results of computations of 13 gravity profiles. Accordingto the relief of the Mohorovicic Discontinuity, this part of the Liaoning Provincemay be divided into three elongated regions, northeast-southwest in direction: thecentral, southeastern and northwestern. The central region is an uplift of theupper mantle, lowering toward the northeast and extending southwestward into theBohai Gulf. Its southeastern flank is much steeper than the northwestern flank,both sides slope down more or less in steps. On this large tectonic background, aseries of secondary structures of considerable size are located. The thickness of crust on this uplifted region is 31-32 kilometers, but it be-comes about 30 kilometers along the eastern edge. In the southeastern region, thecrustal thickness is 34-35 kilometers in general, maximum, 38 kilometers. In thenorthwestern region, the crustal thickness increases toward northwest, from 34 to 40kilometers. The Haicheng Earthquake occurred on the steeper southeastern slope ofthe central uplifted region. In this paper, a brief description of the methods of computation is also givenand some problems are discussed.更多还原