The application of the Signum transform to the interpretation of magnetic anomalies due to prismatic bodies

Souza, Jeferson de

doi:10.1071/aseg2015ab190

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…The results are signals represented by "plateaus". Signum Transform outlines well borders of dykes and structures well, as it is practically independent of the sources' depth (Souza & Ferreira, 2012, 2015.…”

Section: Magnetometrymentioning

confidence: 87%

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Pereira¹,

Ferreira²

2018

Braz J Geophys

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ABSTRACT. The northeastern portion of Santa Catarina State, southern Brazil, bears important primary gold mineralization associated with granitic intrusions with potassic and phyllic hydrothermal alteration zones and a phase shear zone reactivation. Airborne radiometric and magnetic data were applied in the study area through the use of gamma-ray spectrometry (Total Count, K, eTh and eU) and suggestive parameters of hydrothermal alteration as Kd, Ud and F, in association with geological units, while magnetometry (RTP, THDR, TDR and Signum Transform) was applied in the definition of the structural framework. Geophysical data was interpreted and integrated to geological information, such as lithologic units, structures, shear zones and gold mineralization, using the knowledge driven and index overlay methods in order to define favorable targets. The geophysical and geological data exhibit good correlation, as seen in the gamma-ray spectrometric domains and magnetic lineaments, and the favorability map shows important target areas for primary gold mineralization. It was possible to observe in the geophysical maps that shear zones and faults have more influence in the occurrences than potassic and phyllic hydrothermal alteration related to granitic intrusions.Keywords: geophysical exploration, knowledge-driven, Dom Feliciano Belt.RESUMO. A porção nordeste do estado de Santa Catarina, sul do Brasil, possui importantes mineralizações auríferas primárias associadas a intrusões graníticas com zonas de alteração hidrotermal potássica e fílica e posterior fase de reativação de zonas de cisalhamento. Dados radiométricos e magnéticos aerogeofísicos foram aplicados na área de estudo através do uso de gamaespectrometria (Contagem Total, K, eTh e eU) e parâmetros sugestivos de alteração hidrotermal como Kd, Ud e Parâmetro F. Em associação com unidades geológicas, enquanto a magnetometria (RTP, GHT, ISA e Signum Transform) foi aplicada na definição do arcabouço estrutural. Os dados geofísicos foram interpretados e integrados às informações geológicas, como unidades litológicas, estruturas, zonas de cisalhamento e mineralizações de ouro, utilizando os métodos knowledge-driven e index overlay para definir alvos favoráveis. Os dados geofísicos e geológicos apresentam boa correlação, como visto nos domínios espectrométricos de raios gama e lineamentos magnéticos, e o mapa de favorabilidade mostra áreas-alvo importantes para a mineralização de ouro primária. Foi possível observar nos mapas geofísicos que as zonas de cisalhamento e as falhas têm mais influência nas ocorrências do que as zonas de alteração hidrotermal potássica e fílica relacionada às intrusões graníticas.Palavras-chave: exploração geofísica, knowledge-driven, Cinturão Dom Feliciano.

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Section: Magnetometrymentioning

confidence: 87%

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Pereira¹,

Ferreira²

2018

Braz J Geophys

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“…The causative source will have the value +1. It was suggested to use first-order vertical derivative of the magnetic anomaly, second-order vertical derivative or first-order vertical derivative minus total horizontal derivative as filtering function (Souza & Ferreira, 2015). Signum transform of second-order vertical derivative has given better results in this study.…”

Section: Analytic Signal Ofmentioning

confidence: 87%

“…However, like the TDR, this method depends on the inclination of magnetic field. Signum transform (ST) suggested by Souza and Ferreira (2015) is a simple derivative-based method for qualitative and quantitative interpretation of magnetic anomalies from dyke-like structures. The method is based on the normalization the filtering function by its absolute value.…”

Section: Asa|=√(mentioning

confidence: 99%

Airborne Magnetic Survey and Remote Sensing Applied to Structural Study in Vohilava Area Madagascar

Henri

Rakotondrazafy

2022

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Mananjary district is known for its gold production. To better understand the gold mineralization distribution, a regional structural study was undertaken using airborne geophysics and remote sensing (RS). Magnetometry data, Landsat Operational Land Imager (OLI) 8 satellite-image and DEM (Digital Elevation Model) have been processed and interpreted. Signals associated with deep structures are weak and dominated by strong signals from surficial magnetic sources. To overcome this problem, local-phase based filters were used. A deep knowledge of each filter allows to use it separately or in combination with other filters. RS is a powerful tool for a regional study. Color composite technique and DEM analysis were helpful to bring out faults and structures. The combination of magnetometry and RS allows geologists to efficiently delineate prospective zones. The study has unveiled a dextral strike-slip fault (SSF) over 240km and associated faults, folds, flower structure and pull-apart basins within the Mananjary gold district. Moreover, the SSF structurally controlled the spatial distribution of Vohilava-Nosivolo and Maha groups. R Riedel shear faults appear as North North East – South South West faults. R’ Riedel shear faults occur in the north of the study area with East North East -West South West orientation. Tectonic block rotation occurred between Ampasinambo and Soavina. P’ shear faults striking West North West – East South East occur in Vohilava. Some folds are associated with the SSF as well. Vohilava positive flower structure which used to be a syncline and its antiform equivalent are SSF footprints. The latter was active since Mesoarchean.

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“…For any magnetic anomaly M, which could be the firstor second-order vertical gradient or subtracting the total horizontal gradient from the first-order vertical gradient [33] as expressed in equation (5), the zeros should ideally be at a ± ;…”

Section: Depth Estimation Using Euler Deconvolutionmentioning

confidence: 99%

Analysis of aeromagnetic filtering techniques in locating the primary target in sedimentary terrain: A review

2021

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This article analyzes some aeromagnetic filtering techniques for mitigating deceptive geophysical conceptions that may result in a distorted range of geological information from aeromagnetic data. The implication of using the aeromagnetic method, data processing, and enhancement to distinguish sediment-produced anomalies was considered. Two methods to locate buried faults in aeromagnetic data were compared: Edge and fault detection were considered using the magnetic contrast and horizontal gradient methods, whereas rapid depth estimation was considered using the Euler deconvolution method and Signum method. The general challenge to find the magnetic anomaly depth and delineate edges relies on geophysical filtering techniques discussed in order to maintain its geological relevance. The magnetic-contrast layer model signatures help clarify the existence of intra-sedimentary faults. The horizontal gradient approach relative to other derivative methods has better noise stability and fast adaptation to grids without modifying parameters. However, the Signum transform (ST) approach offers a more special solution in depth estimation than the Euler’s deconvolution approach whose solution relies on the required choice of default shape parameters and windows. The Euler deconvolution procedure may not be able to detect structures found by the ST approach and vice versa. As a result, these techniques may be used in conjunction with one another during analysis, as complementary interpretation tools. This review will however aid in the analysis of information used as a criterion for determining faults using various analytical techniques like ST or Euler deconvolution.

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The application of the Signum transform to the interpretation of magnetic anomalies due to prismatic bodies

Cited by 6 publications

References 11 publications

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Airborne Magnetic Survey and Remote Sensing Applied to Structural Study in Vohilava Area Madagascar

Analysis of aeromagnetic filtering techniques in locating the primary target in sedimentary terrain: A review

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The application of the Signum transform to the interpretation of magnetic anomalies due to prismatic bodies

Cited by 6 publications

References 11 publications

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Airborne Magnetic Survey and Remote Sensing Applied to Structural Study in Vohilava Area Madagascar

Analysis of aeromagnetic filtering techniques in locating the primary target in sedimentary terrain: A review

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Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil

Recognition of Gold Mineralization Favorability Zones Through Airborne Gamma-Ray Spectrometry and Magnetometry in Brusque and Botuverã Region, Southern Brazil