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<p>This study integrates gamma-ray spectrometry, magnetometry, and a digital elevation model to investigate a copper mineral occurrence in the Camaquã Basin. The local geological framework corresponds to the Bom Jardim Group (Hilário Formation), the observed lithologies include andesites, volcanic breccias, and silicified volcanic tuffs. The andesites exhibit two predominant foliation attitude orientations: 125/80 (NE-SW) and 224/30 (NW–SE), and are associated with disseminated point malachite mineralization. The methodology involved geological mapping, ground geophysical survey, and drone-based survey to create the digital elevation model and orthophoto of the study area. Geophysical data were collected in conjunction with a DGPS, comprising a total of 424 measurement points spaced 25&#xa0;m apart, covering an area of approximately 46 hectares. Interpolation of the geophysical data enabled the generation of radiometric maps showing <sup>40</sup>K concentrations ranging from 0.28% to 3.95%, <sup>232</sup>Th from 2.41 to 16.34 eppm, and <sup>238</sup>U from 1.4 to 5.68 eppm. Magnetometric maps include the Total Magnetic Intensity reduce of the IGRF (TMI-IGRF) ranging from −&#xa0;94 to 110 nT, Analytic Signal Amplitude (ASA) from 0.01 to 14.8&#xa0;nT/m, and Total Horizontal Derivative calculate from RTP (THDR-RTP) from 0.01 to 8.65&#xa0;nT/m. The results delineated zones with high potential for both disseminated and vein-type copper mineralization. The disseminated mineralization is characterized by elevated potassium contents (1.42–3.95%), high thorium concentrations (8.51–16.34 eppm), and intermediate magnetic intensities on the TMI (IGRF) map (81–94&#xa0;nT). In contrast, the vein-type mineralization is associated with high magnetic susceptibility anomalies identified in the ASA (1.02–14.8&#xa0;nT/m) and the THDR (RTP) (0.78–8.65&#xa0;nT/m) maps, occurring at depth and along NE–SW and NW–SE structural trends, coinciding with regional fault systems.</p>

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Geophysical Analysis Using Gamma-Ray Spectrometry, Magnetometry, and Digital Elevation Model in a Copper Occurrence Within the Camaquã Sedimentary Basin, Southern Brazil

  • 期刊论文

  • 发表日期：

    2025年11月8日

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  • João Pedro Prado de Oliveira,
  • César Augusto Moreira,
  • Dionísio Uendro Carlos,
  • Lenon Melo Ilha,
  • Marina Fernandes Sanches Barros,
  • Luiza Lima Alves,
  • Daniela Kuranaka,
  • Sissa Kumaira,
  • Henri Masquelin

摘要

This study integrates gamma-ray spectrometry, magnetometry, and a digital elevation model to investigate a copper mineral occurrence in the Camaquã Basin. The local geological framework corresponds to the Bom Jardim Group (Hilário Formation), the observed lithologies include andesites, volcanic breccias, and silicified volcanic tuffs. The andesites exhibit two predominant foliation attitude orientations: 125/80 (NE-SW) and 224/30 (NW–SE), and are associated with disseminated point malachite mineralization. The methodology involved geological mapping, ground geophysical survey, and drone-based survey to create the digital elevation model and orthophoto of the study area. Geophysical data were collected in conjunction with a DGPS, comprising a total of 424 measurement points spaced 25 m apart, covering an area of approximately 46 hectares. Interpolation of the geophysical data enabled the generation of radiometric maps showing 40K concentrations ranging from 0.28% to 3.95%, 232Th from 2.41 to 16.34 eppm, and 238U from 1.4 to 5.68 eppm. Magnetometric maps include the Total Magnetic Intensity reduce of the IGRF (TMI-IGRF) ranging from − 94 to 110 nT, Analytic Signal Amplitude (ASA) from 0.01 to 14.8 nT/m, and Total Horizontal Derivative calculate from RTP (THDR-RTP) from 0.01 to 8.65 nT/m. The results delineated zones with high potential for both disseminated and vein-type copper mineralization. The disseminated mineralization is characterized by elevated potassium contents (1.42–3.95%), high thorium concentrations (8.51–16.34 eppm), and intermediate magnetic intensities on the TMI (IGRF) map (81–94 nT). In contrast, the vein-type mineralization is associated with high magnetic susceptibility anomalies identified in the ASA (1.02–14.8 nT/m) and the THDR (RTP) (0.78–8.65 nT/m) maps, occurring at depth and along NE–SW and NW–SE structural trends, coinciding with regional fault systems.