广东阳江深井中的变化地磁场特征研究

Study of Variable Geomagnetic Field Characteristics in the Deep Boreholes in Yangjiang City, Guangdong Province

深井地磁观测是现今地磁学研究中地磁观测的新技术新方法。通过对广东阳江市双捷、罗阳二个钻孔的井中地磁观测和岩石磁性测量,结合广东省地震局肇庆地磁基准台的观测数据,对比分析不同观测环境中的同步地磁观测数据,得到了几点结果:①罗阳台钻井石灰岩的平均剩余磁化强度为5.53E-04(A.M-1),平均质量磁化率为7.10E-08(m^3/kg);双捷台花岗闪长岩的平均剩余磁化强度为1.00E-01(A.M-1),平均质量磁化率为1.39E-06(m^3/kg);②在磁平静时段中深井中的变化地磁场特征和基准地磁台的相近,但在磁扰时段中两者之间相差较大;深井中的变化地磁场受其围岩的岩石磁性影响很大,弱磁性围岩中的响应小,而强磁性围岩中的响应大。③深井中的变化磁场受围岩介质屏蔽和衰减效应影响,也受介质的感应电磁场影响;但后者要比前者的影响更大一些。

Deep borehole geomagnetic observation is a new technique and method in geomagnetic research field.Based on geomagnetic observation and rock magnetism measurement in Shuangjie and Luoyang boreholes in Yangjiang city,Guangdong province,by combining observation data from Zhaoqing Geomagnetic Reference Station of Guangdong Earthquake Agency with comparative analysis of synchronous geomagnetic observation data in different observation environments,several results are obtained:the average remanent magnetization of limestone in Luoyang drilling is 5.53E-04(A.M-1)while the average mass susceptibility is 7.10E-08(m^3/kg);the average remanent magnetization of granodiorite in Shuangjie drilling is 1.00E-01(A.M-1)while the average mass susceptibility is 1.39E-06(m^3/kg);the variable geomagnetic field characteristics in the deep borehole during the magnetic quiet period is similar to that of the geomagnetic reference station,but there is a big difference between them in the magnetic disturbance period.the variable geomagnetic field in deep borehole is greatly affected by the rock magnetism of its surrounding rock,and the response of weakly magnetic surrounding rock is small while that of strongly magnetic surrounding rock is large;the variable magnetic field in deep borehole is influenced by the shielding and attenuation effects of surrounding rock media,as well as the induced electromagnetic field of the media.However,the latter is more influential than the former.