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A proposed procedure for ameliorating edge effects in magnetic data transformations
Geophysical Prospecting ( IF 2.6 ) Pub Date : 2020-05-20 , DOI: 10.1111/1365-2478.12954
Peter G. Lelièvre 1 , Dominique Fournier 2 , Sean E. Walker 3 , Nicholas C. Williams 4 , Colin G. Farquharson 1
Affiliation  

ABSTRACT Reduction to pole and other transformations of total field magnetic intensity data are often challenging to perform at low magnetic latitudes, when remanent magnetization exists, and when large topographic relief exists. Several studies have suggested the use of inversion‐based equivalent source methods for performing such transformations under those complicating factors. However, there has been little assessment of the importance of erroneous edge effects that occur when fundamental assumptions underlying the transformation procedures are broken. In this work we propose a transformation procedure that utilizes magnetization vector inversion, inversion‐based regional field separation and equivalent source inversion on unstructured meshes. We investigated whether edge effects in transformations could be reduced by performing a regional separation procedure prior to equivalent source inversion. We applied our proposed procedure to the transformation of total field magnetic intensity to all three Cartesian magnetic field components using a complicated synthetic example based on a real geological scenario from mineral exploration. While the procedure performed acceptably on this test example, the results could be improved. We pose many questions regarding the various choices and control parameters used throughout the procedure, but we leave the investigation of those questions to future work.

中文翻译:

一种改善磁性数据转换中边缘效应的建议程序

摘要 在低磁纬度、存在剩磁和大地形起伏的情况下,对全场磁场强度数据的极点化简和其他变换通常具有挑战性。几项研究建议使用基于反演的等效源方法在这些复杂因素下执行此类转换。然而,当转换过程的基本假设被破坏时,错误边缘效应的重要性几乎没有评估。在这项工作中,我们提出了一种转换程序,该程序利用磁化矢量反演、基于反演的区域场分离和非结构化网格上的等效源反演。我们研究了是否可以通过在等效源反演之前执行区域分离程序来减少转换中的边缘效应。我们使用基于矿物勘探的真实地质场景的复杂合成示例,将我们提出的程序应用于将总磁场强度转换为所有三个笛卡尔磁场分量。虽然该程序在此测试示例上执行得可以接受,但结果可以改进。我们对整个过程中使用的各种选择和控制参数提出了许多问题,但我们将这些问题的调查留给未来的工作。我们使用基于矿物勘探的真实地质场景的复杂合成示例,将我们提出的程序应用于将总磁场强度转换为所有三个笛卡尔磁场分量。虽然该程序在此测试示例上执行得可以接受,但结果可以改进。我们对整个过程中使用的各种选择和控制参数提出了许多问题,但我们将这些问题的调查留给未来的工作。我们使用基于矿物勘探的真实地质场景的复杂合成示例,将我们提出的程序应用于将总磁场强度转换为所有三个笛卡尔磁场分量。虽然该程序在此测试示例上执行得可以接受,但结果可以改进。我们对整个过程中使用的各种选择和控制参数提出了许多问题,但我们将这些问题的调查留给未来的工作。
更新日期:2020-05-20
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