基于重磁泊松定理的磁化方向估计及应用:以相山铀矿田为例  

Estimating magnetization direction of field sources based on Poisson′s theorem of gravity and magnetic anomaly and its application:a case study of Xiangshan uranium orefield

作　　者：王彦国[1,2] 邓居智 葛坤朋[1] 刘祜[3] WANG YanGuo;DENG JuZhi;GE KunPeng;LIU Hu(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Geophysics and Measurement-Control Technology,East China University of Technology,Nanchang 330013,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,南昌330013 [2]东华理工大学地球物理与测控技术学院,南昌330013 [3]核工业北京地质研究所,北京100029

出　　处：《地球物理学报》2022年第12期4914-4929,共16页Chinese Journal of Geophysics

基　　金：国家重点研发计划项目(2017YFC0602603);国家自然科学基金(41504098,41862013);江西省自然科学基金(20212BAB203005);核资源与环境国家重点实验室开放基金(2020NRE25)联合资助.

摘　　要：磁化方向的确定对磁异常处理、反演及解释方面有着重要的参考价值.然而,目前常用的磁化方向估计方法易受计算窗口尺度、化极或叠加异常等影响.为此,本文从重磁泊松定理出发,推导出了磁化强度、磁异常一阶导数及重力位三阶导数的关系式,并在此基础上构建出了可反演磁化强度三分量的线性方程组,进而获得了场源的磁化倾角与偏角.模型试验表明,本文方法能够在多场源的叠加重、磁异常上,有效地反演出各场源的磁化方向,但噪声会在一定程度上降低反演精度,尤其对小规模场源的磁化方向影响较明显.将本方法应用于江西相山铀矿田重磁资料之中,获得了10个测算点的磁化方向,推断了这些测算点位置上重磁同源体的岩石类型,结果表明了研究区内碎斑熔岩具有强剩磁特征,而流纹英安岩则为顺磁性物质,且认为碎斑熔岩之下广泛分布着流纹英安岩,这对该地区组间界面部位铀矿找矿具有重要的指导意义.Magnetization direction determination plays an important role in magnetic data processing,inversion and interpretation.However,the common methods for estimating the magnetization direction are easily affected by the size of computing window,reduced to the pole or superimposed anomalies.In this paper,the relational expressions of the first-order derivatives of magnetic anomaly,the third-order derivatives of gravitational potential and magnetization intensity are derived by using the Poisson′s theorem.The linear equations are established to solve the three components of magnetization intensity,and then the magnetization inclination and declination can be obtained.Model tests show that the magnetization direction of each source can be inverted by the new method for superimposed gravity and magnetic anomalies of multi-sources.However,the inversion precision would be reduced by random noise,especially the magnetization direction of smaller sources.The method is applied to gravity and magnetic data over Xiangshan uranium orefield,and the magnetization directions of 10 selected computing points are obtained and the rock types of gravity and magnetic bodies at these points are also inferred.Furthermore,we think that the porphyroclastic lava has strong remant magnetization and the rhyodacite is paramagnetic rock,and the rhyodacite are widely distributed under the porphyroclastic lava.It has great significance in metallogenetic prediction of uranium deposit via the interface of porphyroclastic lava and rhyodacite.

关 键 词：泊松定理 磁化方向 反演 相山铀矿田 

分 类 号：P631[天文地球—地质矿产勘探]