@InProceedings{CostaPerrSouz:2017:RePrEs,
               author = "Costa, Manoel Augusto Correa da and Perrotta, Monica Mazzini and 
                         Souza Filho, Carlos Roberto",
                title = "Resultados preliminares de espectroscopia de reflect{\^a}ncia e 
                         imageamento hiperespectral na regi{\~a}o da mina de scheelita de 
                         Breju{\'{\i}} (RN), Faixa Serid{\'o}, Prov{\'{\i}}ncia 
                         Borborema",
            booktitle = "Anais...",
                 year = "2017",
               editor = "Gherardi, Douglas Francisco Marcolino and Arag{\~a}o, Luiz 
                         Eduardo Oliveira e Cruz de",
                pages = "5737--5744",
         organization = "Simp{\'o}sio Brasileiro de Sensoriamento Remoto, 18. (SBSR)",
            publisher = "Instituto Nacional de Pesquisas Espaciais (INPE)",
              address = "S{\~a}o Jos{\'e} dos Campos",
             abstract = "The Serid{\'o} mobile belt in the Borborema Province, 
                         northeastern Brazil, hosts a wealth of metallic occurrences, 
                         including the Breju{\'{\i}} W-Mo skarn deposit. Here we present 
                         preliminary results on reflectance spectroscopy and hyperspectral 
                         remote sensing applied to mineral mapping of host rocks and 
                         alteration zones in this classic skarn. Visible and infrared 
                         (VNIR-SWIR; 0.4-2,5 µm) lab spectroscopy was conducted using the 
                         ASD-FieldSpec-3 Hi-Resolution spectrometer. Contact spectral 
                         measurements allowed the identification of hornblende, chlorite 
                         (Mg-rich types), epidote, calcite, gypsum, phengitic illite and 
                         nontronite in the alteration zones, which correspond to retrograde 
                         hydrothermal assemblages associated to the W-Mo ore bodies. 
                         Actinolite, calcite, Fe/Mg-biotite, montmorillonite and kaolinite 
                         were depicted in the host rocks (schists, marbles, calc-silicate 
                         gneisses and pegmatites). Actinolite in calc-silicate gneisses 
                         suggests a more pervasive alteration mineral phase. Nontronite and 
                         phengitic illite are key minerals that characterize the 
                         hydrothermal system. The dominant presence of Mg-chlorite (FeOH = 
                         2,249 µm) in the alteration zones is distinct from the 
                         Fe/Mg-biotite (FeOH = 2,253 µm) found in the host rocks (schists). 
                         Additionally, the increase in the CO3 feature depth is also 
                         typical of these alteration zones (hydrothermal calcites). The 
                         Brejui deposit was also remotely sensed by the ProSpecTIR-VS 
                         airborne hyperspectral imager, with 357 bands between the 
                         VNIR-SWIR range, at 2m spatial resolution. The data was processed 
                         by a stepwise approach including Minimum Noise Fraction (MNF), 
                         Pixel Purity Index (PPI) and Spectral Angle Mapper (SAM) methods. 
                         The classification map yielded from these procedures allowed 
                         mapping of marbles and calcsilicate rocks spatially close to the 
                         skarn mineralization.",
  conference-location = "Santos",
      conference-year = "28-31 maio 2017",
                 isbn = "978-85-17-00088-1",
                label = "60170",
             language = "pt",
         organisation = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                  ibi = "8JMKD3MGP6W34M/3PSMBKJ",
                  url = "http://urlib.net/ibi/8JMKD3MGP6W34M/3PSMBKJ",
           targetfile = "60170.pdf",
                 type = "Radiometria e sensores",
        urlaccessdate = "27 abr. 2024"
}