The nature of geologic source in Euler deconvolution

What is it about?

Euler deconvolution has been widely used in automatic aeromagnetic interpretations because it requires no knowledge about the source magnetization vector and assumes no particular interpretation model. Usually, Euler deconvolution is used to estimate magnetic source location. However, Euler deconvolution requires the correct estimation of the structural index which is related to the nature of the geologic source. We propose a new method to determine the structural index (nature of geologic source) that uses the minimum standard deviation of base-level (i.e., data background) estimates over the source. The nature of geologic source can be: faults, thin dike, magmatic pipe or magmatic chamber. We show that previous criterion to determine the structural index based on a tight clustering in Euler depth estimates fails in the presence of interfering anomalies. Rather, the proposed method is theoretically sound and tests with simulated and real datasets indicate its practical utility in determining the best value for the structural index even in the case of strongly interfering anomalies. We take advantage of all Euler estimates without any transformation or extra computation. For isolated anomalies, depth estimates form plateaus over the magnetic source and we apply the proposed method on these areas. On the other hand, for cases with interfering anomalies, we apply the proposed method on the plateaus formed on the Euler horizontal estimates; these plateaus locate the horizontal positions of the geologic sources. Application to real magnetic data-set of the Goiás Alkaline Province, Brazil, illustrate the applicability of the proposed method to interpret a complex geologic setting. However, we stress that the proposed method works to interpret magnetic anomalies produced by ideal sources (e.g., single pole, point dipole, line of dipoles) .

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