摘要
泰安一诸城高精度重力观测剖面,位于华北克拉通的东部,是中国东部重要的构造带且是地震活动的重要地段,利用剖面相对重力联测与同址GNSS三维坐标测量数据,得到剖面的重力异常,结合区域布格重力场、地球深部探测及地质构造成果,对剖面进行密度结构反演和剩余密度相关成像研究.结果表明:剖面布格异常变化范围为(-30.1~7.3)×10^(-5) m·s^(-2),从西往东总体呈上升(泰安至沂源以低背景平缓逐渐上升与相应位置的高程呈现“同步型”变化;马站至张家楼以高背景逐渐上升与地形高程呈现“镜像型”变化)趋势,高低异常背景转折在沂沭断裂带西段150 km左右位置;背景异常是地壳厚度变化的反映,整体形态西深东浅,在沂沐断裂带地壳厚度隆起可能是地壳下地幔物质沿断裂向上入侵时,地壳产生挤压和膨胀隆起所致;剖面地壳密度呈现上、中和下三层结构,鲁西隆起、沂沭断裂带西部中下地壳局部存在低密度体,可能是上地幔物质上涌岩石含部分高温流体和熔融岩体所致,胶东地区保持了比较完整和均一的地壳结构特征,反映了胶东地区地壳活动不强;剖面的主要断裂带位置均能看到布格重力异常和剩余密度的变化,可能是断裂控制了地下介质的发育所致;剖面密度模型显示地下密度的分段特征和深浅构造差异,沂沭断裂带是鲁西隆起和胶东隆起的分界带;本文通过对布格重力异常和密度结构的特征研究,分析了地震活动、动力学背景与地壳密度结构的关系.
The high-precision gravity observation profile of Tai′an-Zhucheng,located in the east part of the East China Craton,is an important tectonic zone in eastern China and an important area of seismic activity.The gravity anomaly of the profile is obtained by using the data of relative gravity joint measurement and GNSS three-dimensional coordinate measurement at the same site.Combined with the results of regional Bouguer gravity field,deep earth exploration and geological structure,density structure inversion and residual density correlation imaging studies were performed on the profiles.The results show that the anomalous variation of the profile Bouguer ranges from(-30.1 to 7.3)×10^(-5) m·s^(-2),with an overall rising trend from west to east.From Tai′an to Yiyuan,the low background rises gently and gradually with the elevation of the corresponding position showing a“synchronous”change.From Mazhan to Zhangjialou,the high background gradually rises and the topographic elevation shows a“mirror image”change.The turning point of high-low anomaly background is about 150 km in the western part of Yishu Fault Zone.The background anomaly is a response to the change of crustal thickness,and the overall pattern is deep in the west and shallow in the east.The crustal thickness rise in the Yimu Fracture Zone is probably due to the extrusion and expansion of the crust when the crust and lower mantle material invades upward along the fracture.The crustal density of the profile shows three layers of structure:upper,middle and lower.There are low-density bodies in the middle and upper crust in the western part of Luxi Uplift and Yishu Fault Zone,which may be caused by the upwelling rocks of upper mantle material containing part of high-temperature fluid and molten rock mass.The crustal structure in the Jiaodong area is relatively intact and homogeneous,which reflects that the crustal activity in the Jiaodong area is not strong.Bouguer gravity anomalies and variations in residual density can be seen at the locations of
作者
罗翔飞
秦建增
李洋洋
李勇江
宋金跃
姚家骏
王泽源
LUO XiangFei;QIN JianZeng;LI YangYang;LI YongJiang;SONG JinYue;YAO JiaJun;WANG ZeYuan(Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第7期2336-2346,共11页
Chinese Journal of Geophysics
基金
地震监测运维(流动重力),国家自然科学基金(41274113)
地震行业科研专项(201508009-08)联合资助.
关键词
重力剖面
布格重力异常
剩余密度相关成像
反演
地壳密度结构
Gravity profile
Bouguer gravity anomaly
Residual density correlation imaging
Inversion
Structure of the crustal density
