秦建增,,
李洋洋,
李勇江,
宋金跃,
姚家骏,
王泽源
中国地震局地球物理勘探中心, 郑州 450002
基金项目: 地震监测运维（流动重力），国家自然科学基金（41274113）和地震行业科研专项（201508009-08）联合资助
详细信息
作者简介: 罗翔飞, 女, 1972年生, 高级工程师, 研究方向: 流动重力监测与地震预报研究.E-mail: 43334123@qq.com
通讯作者: 秦建增, 男, 1963年生, 高级工程师, 主要从事流动重力监测与地震预报等研究.E-mail: jzqin@163.com
中图分类号: P312;P631收稿日期:2020-10-13
修回日期:2021-01-27
上线日期:2021-07-10
Gravity anomalies and crustal density structure characteristics of profile Tai'an-Zhucheng
LUO XiangFei,QIN JianZeng,,
LI YangYang,
LI YongJiang,
SONG JinYue,
YAO JiaJun,
WANG ZeYuan
Geophysical Exploration Center, China Earthquake Administration, Zhengzhou 450002, China
More Information
Corresponding author: QIN JianZeng,E-mail:jzqin@163.com
MSC: P312;P631--> Received Date: 13 October 2020
Revised Date: 27 January 2021
Available Online: 10 July 2021
摘要
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）×10-5m·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.
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
Abstract: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)×10-5m·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 the major fracture zones in the section. This may be caused by the fractures controlling the development of the subsurface medium. The profile density model shows segmental characteristics of subsurface density and deep and shallow tectonic differences. The Yishu Fault Zone is the demarcation zone between the Luxi Uplift and the Jiaodong Uplift. In this paper, we investigate the characteristics of the gravity and density structure of the profile Bouguer and analyze the relationship between seismic activity, dynamical background and the density structure of the crust.
Key words:Gravity profile/
Bouguer gravity anomaly/
Residual density correlation imaging/
Inversion/
Structure of the crustal density
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