基于伪磁梯度张量混合方向tilt梯度的磁源定位方法及其应用:以内蒙古塔木素铀矿床为例  

Magnetic source positioning method based on the mixed directional tilt gradients of pseudo gradient tensor and its application:a case study of Tamusu uranium orefield,Inner Mongolia

作　　者：王彦国[1,2] 林昭翰 邓居智 郭华[3] 郝梦成 Sulaiman Garba Yana WANG YanGuo;LIN ZhaoHan;DENG JuZhi;GUO Hua;HAO MengCheng;Sulaiman Garba Yana(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;China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,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]中国自然资源部航空物探遥感中心,北京100083

出　　处：《地球物理学报》2024年第5期2043-2056,共14页Chinese Journal of Geophysics

基　　金：国家重点研发计划项目(2023YFC2906602);国家自然科学基金项目(41504098,42064008,42074115,42130811);江西省自然科学基金项目(20212BAB203005,20212BCJ23001)联合资助。

摘　　要：斜磁化磁源的准确定位是磁法勘探有效圈定场源分布及划分断裂构造的重要依据.但受磁化方向影响,总磁异常与地质体分布并无明显对应关系.为此,本文从总磁异常垂向积分出发,推导出了伪磁梯度张量,定义了伪磁梯度张量的混合方向tilt梯度及混合方向解析信号振幅,提出了基于伪磁梯度张量混合方向tilt梯度水平导数组合的场源定位方法.模型试验表明,相对于解析信号振幅、tilt梯度的总水平导数及方向tilt梯度的总水平导数模这3种受磁化方向影响较小的方法,本文提出的磁源定位方法能够更有效地反映出不同磁化方向的磁源位置,具有更强的识别能力和定位精度.在内蒙古塔木素铀矿床的航磁资料应用中,新方法较好地展示出了已知断裂带的展布及出露岩浆岩的分布,同时有效地提取了塔木素铀矿床上方的弱磁异常信息,处理结果为研究区圈定隐伏岩体、划分隐伏断裂及扩大铀矿找矿靶区提供了依据.Accurate positioning of magnetic source with non-vertical magnetization is an important basis for delineating the source distribution and dividing the faulted structures by using magnetic prospecting.The total magnetic anomalies are not good agreement with the distribution of geological bodies because of the influenced of magnetization direction.In order to reduce the influenced of magnetization direction,this paper derives the pseudo gradient tensor from the vertical integral of the total magnetic anomaly,and defines the mixed directional tilt gradients and analytic signal amplitudes of pseudo magnetic gradient tensor.And then we introduce a new magnetic source positioning method based on the combination of the horizontal derivatives of the mixed directional tilt gradients.Model tests indicates that the new method can effectively reflect the locations of magnetic sources with different magnetization directions,and has stronger recognition ability and positioning accuracy than the analytic signal amplitude,the total horizontal derivative of tilt gradient and the total horizontal derivative of the directional tilt gradient.When we apply the different methods to aeromagnetic data over the Tamusu uranium orefield,the new method preferably displays the trends of faults and the distributions of exposed magmatic rocks.In addition,the weak magnetic signals of Tamusu uranium orefield are extracted by the new method.Meanwhile,the results can be used to delineate the hidden rock masses,divide the concealed faults and enlarge the prospecting targets of uranium mine.

关 键 词：总磁异常 磁梯度张量 方向tilt梯度 磁源定位 塔木素铀矿床 

分 类 号：P631[天文地球—地质矿产勘探]