Abstract: In eastern China, there is a great gravity anomaly zone which extends from the Daxinganling Mountains, through the Taihang Mountains to the Wuling Mountains. This zone is presumably associated with the structural variation in the deep crust. We select the Fuping Dingzhou profile, which is perpendicular to this gravity anomaly zone, to make an inversion analysis of the crust upper mantle density using the data of seismic sounding and Bouguer anomaly. The result shows that the density distribution of the crust and upper mantle along this profile is evidently heterogeneous. The general feature is that the density is relatively low in the west and high in the east. The lateral variation of the crustal thickness basically determines the generation of the Bouger gravity anomaly zone. Taken the Mesozoic and Cenozoic tectonic evolution of North China into account, it is suggested that this gravity anomaly zone was developed after the Yanshan period and associated with plate interaction and thermal mass transfer of the upper mantle.

Key words: Taihang Mountains, gravity zone, density structure, optimum inversion method

摘要： 斜贯中国东部地区的大兴安岭-太行山-武陵山重力梯级带是一条地壳深部构造变异带。选择与其中段——太行山重力梯级带相垂直的阜平-定州剖面,利用人工地震测深与布格重力异常资料,进行了地壳-上地幔密度反演分析。结果表明,该剖面的地壳-上地幔密度分布具有明显的不均匀性。总体特征是剖面西部密度较低,东部密度较高,地壳厚度的横向变化基本上决定了布格重力异常梯级带的形成。结合华北地区的中新生代构造演化,认为太行山重力梯级带是燕山期以后形成的,它与板块之间的相互作用及上地幔热物质的运动相关。

关键词: 太行山, 重力梯级带, 密度结构, 最优化反演方法