Caracterização geológica – geofísica da porção central do Amapá com base em processamento e interpretação de dados aerogeofísicos

Magalhães, Lucíola Alves; Filho, Carlos Roberto de Souza; Silva, Adalene Moreira

doi:10.25249/0375-7536.2007373464477

Cited by 13 publications

(2 citation statements)

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“…The grid cell size was defined as 125 m (a quarter of the flight line spacing). Details of the data processing procedures and the products generated can be found in Magalhães et al (2007). Among the aerogeophysical data products produced for this work, maps of analytic signal amplitude, magnetic lineaments interpreted from horizontal and vertical derivatives, and individual radiometric elements (K, Th, and U) were used as evidential themes in mapping the mineral potential (Figs.…”

Section: Aerogeophysical Datamentioning

confidence: 99%

Targeting of Gold Deposits in Amazonian Exploration Frontiers using Knowledge- and Data-Driven Spatial Modeling of Geophysical, Geochemical, and Geological Data

Magalhães¹,

Filho²

2011

Surv Geophys

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This paper reports the application of weights-of-evidence, artificial neural networks, and fuzzy logic spatial modeling techniques to generate prospectivity maps for gold mineralization in the neighborhood of the Amapari Au mine, Brazil. The study area comprises one of the last Brazilian mineral exploration frontiers. The Amapari mine is located in the Maroni-Itaicaiúnas Province, which regionally hosts important gold, iron, manganese, chromite, diamond, bauxite, kaolinite, and cassiterite deposits. The Amapari Au mine is characterized as of the orogenic gold deposit type. The highest gold grades are associated with highly deformed rocks and are concentrated in sulfide-rich veins mainly composed of pyrrhotite. The data used for the generation of gold prospectivity models include aerogeophysical and geological maps as well as the gold content of stream sediment samples. The prospectivity maps provided by these three methods showed that the Amapari mine stands out as an area of high potential for gold mineralization. The prospectivity maps also highlight new targets for gold exploration. These new targets were validated by means of detailed maps of gold geochemical anomalies in soil and by fieldwork. The identified target areas exhibit good spatial coincidence with the main soil geochemical anomalies and prospects, thus demonstrating that the delineation of exploration targets by analysis and integration of indirect datasets in a geographic information system (GIS) is consistent with direct prospecting. Considering that work of this nature has never been developed in the Amazonian region, this is an important example of the applicability and functionality of geophysical data and prospectivity analysis in regions where geologic and metallogenetic information is scarce.

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Section: Aerogeophysical Datamentioning

confidence: 99%

Targeting of Gold Deposits in Amazonian Exploration Frontiers using Knowledge- and Data-Driven Spatial Modeling of Geophysical, Geochemical, and Geological Data

Magalhães¹,

Filho²

2011

Surv Geophys

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“…Após a aquisição dos dados magnetométricos, para se aplicar as técnicas de processamento 2D, é necessário que os dados estejam distribuídos em uma malha regular (Magalhães et al, 2016). Algumas técnicas de interpolação utilizadas frequentemente para dados de magnetometria são: Interpolação por Mínima Curvatura (Briggs, 1974), Interpolação pelo Inverso da Distância Ponderada e Interpolação Bi-direcional.…”

Section: Interpolação De Dadosunclassified

Caracterização magnetomérica do Kimberlito Janjão, Domo de Lages, Santa Catarina

Coelho¹

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This work presents a review of the ground magnetometry technique, with detailed information regarding its planning, acquisition and data processing. The technique was applied in an area of 0.7 km 2 in the Planalto Catarinense, in the Dome of Lages. The Dome of Lages differs from the other domes of the Paraná Basin by the presence of alkaline rocks with an age of approximately 75 Ma. These rocks, in the 70s and 80s of the last century, were the subject of investigations mainly mineralogical and petrological. The detailed magnetic survey presented in this work had the goal of inferring the geometry of a kimberlite body, named "Janjão"(in homage to its discoverer). Geophysical work, previously performed in this region, had low resolution and low representativity of the study area. This work allowed to generate an anomalous magnetic field map that presented two dipole anomalies. These anomalies presented reverse bias to those expected for induced anomalies in the latitude and inclination of the magnetic field of the survey region, indicating strong remanent magnetization in the rocks studied. The Analytical Signal Amplitude technique provided information about the lateral limits of the magnetic bodies that generate the anomalies. An estimation of the depth of the top of these bodies was also made from the Half-Width technique and the 3D Euler Deconvolution. The results obtained between the two techniques were compatible. The information obtained through the processing of the magnetic data served as a basis to evaluate the model generated by the Inversion of the Magnetization Vector. The inversion presented a model of magnetic susceptibility distribution in subsurface and two sub verticalized magnetic bodies, with magnetization vector opposite the main direction of the geomagnetic field, associated to the positions of the kimberlite body. The values of magnetic susceptibility ranged from 8 to 20 × 10 −3 (SI). For the susceptibility of 8 × 10 −3 (SI), the magnetic bodies relating to the two anomalies are connected to each other at depths of approximately 180 meters. The magnetization vector indicated weak magnetic susceptibility and magnetization primarily induced in regions where it is estimated the presence of sedimentary rocks nesting to Janjão diatreme, whose physical characteristics are compatible with those suggested by the inversion model. Finally, with the hypothesis of reverse magnetic field at the time of diatreme formation and with the estimated ages for these kimberlite rocks, it was possible to reduce the age uncertainty of the Janjão diatreme formation. For future work, was mentioned the location of 16 other kimberlite occurrences in the dome region and also proposed the use of gravimetry and electromagnetic techniques that may help in the identification and characterization of these occurrences, and thus, contribute to the knowledge about the Lages Kimberly Province in Santa Catarina.

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Geochemistry and origin of the Rhyacian tholeiitic metabasalts and meta-andesites from the Vila Nova Greenstone Belt, Guyana Shield, Amapá, Brazil

Hoffmann

Philipp

Borghetti

2018

Journal of South American Earth Sciences

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Caracterização geológica – geofísica da porção central do Amapá com base em processamento e interpretação de dados aerogeofísicos

Cited by 13 publications

References 1 publication

Targeting of Gold Deposits in Amazonian Exploration Frontiers using Knowledge- and Data-Driven Spatial Modeling of Geophysical, Geochemical, and Geological Data

Targeting of Gold Deposits in Amazonian Exploration Frontiers using Knowledge- and Data-Driven Spatial Modeling of Geophysical, Geochemical, and Geological Data

Caracterização magnetomérica do Kimberlito Janjão, Domo de Lages, Santa Catarina

Geochemistry and origin of the Rhyacian tholeiitic metabasalts and meta-andesites from the Vila Nova Greenstone Belt, Guyana Shield, Amapá, Brazil

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