Canoas geophysical anomaly: A possible alkaline body or unusual anomaly caused by mafic dykes in the Ponta Grossa Arch, Brazil?

Louro, Vinicius Hector Abud; Negrão, André Pires; Castro, Luís Gustavo de; Ferreira, Francisco José Fonseca

doi:10.1016/j.jappgeo.2019.103857

Cited by 2 publications

(1 citation statement)

References 45 publications

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“…24) than in the source location (x 0 , z 0 ). Our study area is located in the Ponta Grossa Arch (PGA), southern Brazil, which has been the subject of several recent studies (e.g., Strugale et al, 2007;Gomes et al, 2011;Louro et al, 2019;Cavalcante et al, 2020).…”

Section: R a F Tmentioning

confidence: 99%

Interpretation of magnetic anomaly profiles using a decomposition in Hilbert transform pairs

Oliveira

Souza

Castro³

et al. 2022

Braz J Geophys

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ABSTRACT. We propose a simple transformation to aid the interpretation of magnetic anomalies generated by linear structures. The profile of such anomalies perpendicular to the strike can be decomposed into two signals, one symmetric and the other antisymmetric concerning the center of the source. The symmetric component serves as input data to various depth estimation techniques that often assume the anomaly is reduced to the pole. We use the fact that these components form a Hilbert transform pair to transform a skewed anomaly profile into a symmetric one. Unlike in previous works that rely on the decomposition into even and odd functions, the profile does not need to be shifted to the source's center of symmetry or limited to one isolated anomaly. Multiple effective magnetization directions presented by different dikes are modeled by a function representing the different local effective dip angles. We validate the method with synthetic data and ground magnetic survey data from a dike swarm at Ponta Grossa Arch, southern Brazil. We also illustrate the usefulness of reconstructed anomalies for depth estimation methods. The results also show that the method can handle interfering sources with distinct effective magnetization directions.

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Section: R a F Tmentioning

confidence: 99%

Interpretation of magnetic anomaly profiles using a decomposition in Hilbert transform pairs

Oliveira

Souza

Castro³

et al. 2022

Braz J Geophys

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Magnetic and radiometric signatures of alkaline rocks and gabbros from the Ponta Grossa Arch, southeastern Paraná Basin, Brazil

Silva

Ferreira

2021

Braz. J. Geol.

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We present airborne magnetic and radiometric characteristics of some igneous suites from the Ponta Grossa Arch Alkaline Province (southern Brazil), namely the Bairro da Cruz, Banhadão, Barra do Itapirapuã, Mato Preto and Tunas complexes, Barra do Teixeira Phonolite, Itapirapuã Nepheline syenite, and José Fernandes Gabbro. We applied magnetic susceptibility 3D inversions using the total magnetic anomaly data together with its analytic signal of the vertical integral and the vertical integral of the analytic signal for the Bairro da Cruz, José Fernandes, and Tunas intrusions. Gamma-ray spectrometric methods involved analyses of basic, ternary, and ratio maps, thorium-normalized parameters, and radioelement concentrations at sampled data points. Stacked profiles from geophysical data were generated for each rock. The Bairro da Cruz, José Fernandes, and Tunas intrusions are associated with dipolar anomalies with normal polarity whereas their inversions show low magnetic susceptibility values. Gamma-ray spectrometric results allowed us to verify that all complexes are enriched mainly in eTh. Carbonatite bodies showed the highest contents of eTh and eU. Our findings are consistent with geophysical responses of alkaline bodies and impact the understanding of geophysical signatures, especially radiometric ones, of alkaline provinces in Brazil.

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Canoas geophysical anomaly: A possible alkaline body or unusual anomaly caused by mafic dykes in the Ponta Grossa Arch, Brazil?

Cited by 2 publications

References 45 publications

Interpretation of magnetic anomaly profiles using a decomposition in Hilbert transform pairs

Interpretation of magnetic anomaly profiles using a decomposition in Hilbert transform pairs

Magnetic and radiometric signatures of alkaline rocks and gabbros from the Ponta Grossa Arch, southeastern Paraná Basin, Brazil

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