Depósito vulcanogênico polimetálico (Zn, Pb, Cu ± (Ag-Bi)) Artulândia, Arco Magmático Paleoproterozóico Campinorte, Brasil Central

Filgueiras, Bernardo de Carvalho

doi:10.26512/2015.05.d.18711

Cited by 3 publications

(2 citation statements)

References 60 publications

(148 reference statements)

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“…The Goiás Massif consists of narrow greenstone belts and orthogneiss complexes of predominantly Archean age (Jost et al 2005). The Artulândia Domain is represented by volcano-sedimentary sequence, including acidic volcanic rocks, which are intruded by 2.14 Ga tonalite by U-Pb method (Filgueiras 2015). The Silvânia Sequence is characterized by a narrow range of felsic metavolcanic rocks dated at 2.11 Ga, including amphibolites and metasediments, intruded by 2.0 Ga granites dated by Sm-Nd isotopic analyses (Piuzana 2002).…”

Section: Geological Settingmentioning

confidence: 99%

Characterization and Geological Meaning of the Crystalline Basement Occurrence in the Unaí Region, Minas Gerais State (Central Brasilia Belt)

Moura,

Campos

2023

Anu. Inst. Geociênc.

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Granitoid rocks petrographically and compositionally characterized as tonalite, monzonite granodiorite and granite were observed in restricted areas in the central portion of the external zone of the Brasilia Belt. These outcrops of peraluminous rocks were interpreted as the sialic basement of the region, associated with paleogeographic highs prior to the deposition of the Proterozoic sedimentary cover. U-Pb zircon age of 2.14 Ga and geochemical analysis are compatible with other Paleoproterozoic bedrock areas observed mainly in the north Brasilia Belt. The existence of a basement bulkhead conditioned the Neoproterozoic deformation, causing the inflection of regional structures from NNW to N60-70W and over again to the NNW regional trend. The absence of contact metamorphism along the adjacent supracrustal rocks, regional foliation attitude that is different from that observed in the granitoids (tonalite, granotiorite, monzonite and granite) and the older age, show that these rocks represent basement windows and not younger intrusive bodies, as previously interpreted. The rocks studied in this research are correlated to the Aurumina Suite, which represents the main basement rock set in the North Brasília Belt.

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Section: Geological Settingmentioning

confidence: 99%

Characterization and Geological Meaning of the Crystalline Basement Occurrence in the Unaí Region, Minas Gerais State (Central Brasilia Belt)

Moura,

Campos

2023

Anu. Inst. Geociênc.

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“…A SP é uma grande zona de cisalhamento transcorrente dextral com cerca de 300 km de extensão (Silva et al, 2011), composta por um conjunto de lineamentos estruturais L-O e ONO-ESE, marcando o limite geotectônico entre os segmentos norte e sul da Faixa Brasília . Essa zona de cisalhamento apresenta curvatura voltada para leste, associada à acresção do terreno para a margem oeste do Cráton São Francisco (Filgueiras, 2015). Segundo Araújo Filho & Kuyumjian (1996) e Araújo , a origem da SP é interpretada como uma colisão polifásica compreendendo deformações OSO para ENE, NNO para SSE e OSO para ENE.…”

Section: áRea Iunclassified

Parâmetros de regularização de operadores diferenciais no processamento de dados aeromagnéticos

Melo

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The evaluation of numerical derivatives is an essential tool in magnetic data processing, aiming to map structural lineaments and estimate the depth of the respective anomalous sources in the subsurface. Generally, directional derivatives are obtained through numerical methods based on the calculation of the Fourier transform, susceptible to noise amplification due to numerical instability. One way to improve stability in differentiation is to apply Tikhonov regularization to balance the oscillatory characteristics of the derivatives with the smoothing degree associated with the particular regularization parameter choice. This work proposes a graphical procedure to estimate regularization parameters for different potential field transformations that require first or second-order derivatives. This tool is based on normalizing the L 2 -norm of the respective transformed fields to a trial regularization parameters sequence, resulting in a characteristic function with a staircase format. This function has smooth and monotonic behavior, decreasing from 1 to 0 for increasing regularization values, in which the upper step (1) of the function is associated with non-regularized and sub-regularized transformations and the lower step (0) corresponds to over-regularized transformations. Synthetic tests simulating models with different noise levels or anomaly complexities illustrated that the well-suited regularization parameter selection for transformed fields depends on analyzing the distortions in the maps. Euler deconvolution processing applied to synthetic models showed that the appropriate regularization parameter choice is associated with the ascertaining of erroneous (overestimated) depth inferences. The applicability of the regularization procedure is evaluated on gridded aeromagnetic data covering two study areas in the Tocantins Province, central Brazil. In Area-I, covering the Anápolis-Itauçu Complex, transformations using first-order derivatives regularized with the intermediate ramp criterion were efficient in better mapping the continuity of magnetic lineaments with different directions and intersections, associated with shear zones, geological faults, and intrusive bodies. Applications in Area-II covering the Transbrasiliano tectonic corridor revealed the need for a low-dose regularization to obtain depth estimates consistent with the depths of the underlying basement of the Bananal Basin, according to available information from seismic lines and gravity models.Regularization tuned to the intermediate ramp criterion was sufficient for transformations with first-order derivatives to map the complex pattern of multiple linear structures. The results in Area-II showed that transformations based on second-order derivatives require a high degree of regularization to detect the contributions from subtle structural features.

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The western São Francisco pericraton interpreted from crustal magnetic and gravity sources

Reis

Vidotti

Cordeiro

et al. 2020

Journal of South American Earth Sciences

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Depósito vulcanogênico polimetálico (Zn, Pb, Cu ± (Ag-Bi)) Artulândia, Arco Magmático Paleoproterozóico Campinorte, Brasil Central

Cited by 3 publications

References 60 publications

Characterization and Geological Meaning of the Crystalline Basement Occurrence in the Unaí Region, Minas Gerais State (Central Brasilia Belt)

Characterization and Geological Meaning of the Crystalline Basement Occurrence in the Unaí Region, Minas Gerais State (Central Brasilia Belt)

Parâmetros de regularização de operadores diferenciais no processamento de dados aeromagnéticos

The western São Francisco pericraton interpreted from crustal magnetic and gravity sources

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