宜川—泰安重力剖面的均衡重力异常与地震活动的关系  

Relationship between isostatic gravity anomalies and earthquake activity in the Yichuan-Tai'an gravity profile

作　　者：秦建增[1] 方盛明[1] 罗翔飞[1] 李勇江[1] 贾宇鹏[1] 谢汝一[1] 李怡青[1] 

机构地区：[1]中国地震局地球物理勘探中心,郑州450002

出　　处：《地球物理学进展》2017年第6期2366-2373,共8页Progress in Geophysics

基　　金：国家自然科学基金项目(41274113);地震行业专项"中国综合地球物理场观测-鄂尔多斯地块缘重力观测研究"(201208009);中国综合地球物理场观测-大华北地区重力;地磁观测研究(201508009-08)联合资助

摘　　要：宜川—泰安重力剖面穿越了太行—吕梁隆起、华北裂陷、鲁西隆起等地质构造单元,剖面及其附近地区构造活动强烈.依据布格重力异常特征可分为太行山以西的布格重力异常与地形高程"同步型"的变化特征、太行山以东的布格重力异常与地形高程"镜像型"的变化特征,布格异常转换带位于太行山重力梯级带的东缘,反映了大地质构造单元有着不同的深部构造背景.均衡重力异常特征与新构造运动有着良好的一致性,即正异常区对应吕梁山、太行山以及鲁西等隆起地区,负异常区对应临汾、华北断陷盆地.通过对理论均衡地壳厚度与实际地壳厚度进行对比分析发现,在均衡重力状态异常转换带及其附近地区均对应于莫氏界面上隆、上地幔热物质向地壳侵入和运移,由于其在趋于均衡的过程中必然伴随着地壳的差异运动,因此构造活动强烈而产生深大断裂,表现为地震的频繁活动,这些地区应该是地震监测以及震害防御需要重点关注的地区.The Yichuan-Tai＇an gravity profile goes across a trail of geological tectonic units including the Taihang-Lüliang uplift,the North China rift and Luxi uplift. The profile and its nearby areas are with intensive structural activities. The bouguer gravity anomaly is＂synchronous＂with the height of the terrain to the west of Taihang Mountains（ TM） while it is the ＂Image type＂to the east of TM.The transition zone is located in the eastern margin of the Taihang Mountains gravitational gradient zone,which reflects the different deep tectonic settings of the large geological tectonic units. The isostatic gravity anomaly and neo-tectonic movements have a good consistency that the positive anomaly area corresponds to the Lüliang Mountains,Taihang Mountains and Luxi uplift and the negative anomaly area corresponds to Linfen and North China fault basin.According to the comparative analysis between the theoretical values of isostatic crustal thickness and the actual values of crustal thickness,we found the isostatic anomalies transformation zone and its adjacent areas all correspond to the Moho uplift and hot material invasion and migration from the upper mantle to the crust. Due to the process tending to equilibrium must be accompanied by differential movement of the crust, the performance of strong tectonic activity leading to large deep faults is the frequent occurrence of earthquakes. These areas should be earthquakemonitoring and disaster-prevention areas needing to focus on.

关 键 词：宜川—泰安重力剖面 布格重力异常 均衡重力异常 莫霍界面 地震活动 

分 类 号：P312[天文地球—固体地球物理学] P315[天文地球—地球物理学]