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Can euler deconvolution outline three‐dimensional magnetic sources?
Geophysical Prospecting ( IF 1.8 ) Pub Date : 2020-06-18 , DOI: 10.1111/1365-2478.12988
Elizangela S. Amaral Mota 1, 2 , Walter E. Medeiros 1, 3, 4 , Roberto G. Oliveira 5
Affiliation  

ABSTRACT Severe limitations of the standard Euler deconvolution to outline source shapes have been pointed out. However, Euler deconvolution has been widely employed on field data to outline interfaces, as faults and thrust zones. We investigate the limitations of the 3D Euler deconvolution–derived estimates of source dip and volume with the use of reduced‐to‐the‐pole synthetic and field anomalies. The synthetic anomalies are generated by two types of source bodies: (1) uniformly magnetized prisms, presenting either smooth or rough interfaces, and (2) bodies presenting smooth delimiting interfaces but strong internal variation of magnetization intensity. The dip of the first type of body might be estimated from the Euler deconvolution solution cluster if the ratio between the depth to the top and vertical extent is relatively high (>1/4). For the second type of body, besides dip, the source volume can be approximately delimited from the solution cluster envelope, regardless of the referred ratio. We apply Euler deconvolution to two field anomalies which are caused by a curved‐shape thrust zone and by a banded iron formation. These anomalies are chosen because they share characteristics with the two types of synthetic bodies. For the thrust zone, the obtained Euler deconvolution solutions show spatial distribution allowing to estimate a source dip that is consistent with the surface geology data, even if the above‐mentioned ratio is much less than 1/4. Thus, there are other factors, such as a heterogeneous magnetization, which might be controlling the vertical spreading of the Euler deconvolution solutions in the thrust zone. On the other hand, for the iron‐ore formation, the solution cluster spreads out occupying a volume, in accordance with the results obtained with the synthetic sources having internal variation of magnetization intensity. As conclusion, although Euler deconvolution–derived solutions cannot offer accurate estimates of source shapes, they might provide a sufficient degree of reliability in the initial estimates of the source dip and volume, which may be useful in a later phase of more accurate modelling.

中文翻译:

欧拉解卷积能勾勒出三维磁源吗?

摘要 已经指出了标准欧拉反卷积在勾勒源形状方面的严重局限性。然而,欧拉反褶积已广泛用于现场数据以勾勒出界面,如断层和逆冲带。我们使用减少到极点的合成和场异常来研究 3D 欧拉反卷积衍生的源倾角和体积估计的局限性。合成异常由两种类型的源体产生:(1)均匀磁化的棱柱,呈现光滑或粗糙的界面;(2)物体呈现光滑的定界界面,但内部磁化强度变化很大。如果顶部深度与垂直范围的比值相对较高 (>1/4),则第一类物体的倾角可以从欧拉解卷积解簇中估计出来。对于第二种类型的物体,除了倾角之外,源体积可以从解簇包络中大致划定,而不管参考比率如何。我们将欧拉反褶积应用于由弯曲形状的逆冲带和带状铁地层引起的两个场异常。选择这些异常是因为它们与两种类型的合成体具有相同的特征。对于逆冲带,获得的欧拉解卷积解显示空间分布,即使上述比率远小于 1/4,也可以估计与地表地质数据一致的源倾角。因此,还有其他因素,例如异质磁化,可能会控制欧拉解卷积解在逆冲带中的垂直扩展。另一方面,对于铁矿石的形成,根据使用具有内部磁化强度变化的合成源获得的结果,溶液簇展开占据体积。总之,虽然欧拉解卷积导出的解决方案不能提供源形状的准确估计,但它们可能在源倾角和体积的初始估计中提供足够程度的可靠性,这可能在更准确建模的后期阶段有用。
更新日期:2020-06-18
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