Spectral Signature of Aramo site

The entry Spectral Signature of Aramo from USAL team consists of 9 files corresponding to spectral signatures (SS) of outcropping rocks and soils on Aramo Plateau. The files (in .*asd and -*csv formats) are means of Visible, Near Infrared and Short Wavelength Infrared (VNIR-SWIR) spectra resulting from the supervised classification performed by using geochemical data (supplied by Aurum partner) and spectral and mineralogical information processed from “VNIR-SWIR and XRD datasets”. For this classification, geochemical analyses of 998 samples were considered. Spectral information of from 311 samples of outcropping rocks, 371 samples of soils, and 208 samples from the mine were also used. More than 200 samples were analysed by means of XRD in order to determine the mineralogical composition and to identify mineralogical associations. With all these data the identification of spectral signatures has been performed. Nine mineralogical associations (MA) were identified. The main minerals in outcropping rocks consist of different types of carbonate minerals (calcite and dolomite) together with quartz, clays minerals, malachite, and gibbsite. However, soils mainly consist of clay minerals (interstratified chlorite-smectite and illite), quartz, and occasionally talc or gibbsite. Spectra of samples with similar mineralogical associations have similar morphologies, band positions, intensities and global reflectance in the studied region. A mean spectrum was obtained for each group of samples corresponding to a mineralogical association. Since mineralogical associations and spectral signatures of clusters O3 and O4 cannot be distinguished one from each other, they can be used as a single one. Something similar occurs with two mineralogical associations in soils (S1 and S2) because the presence of talc cannot be identified from the spectra, even from their second derivative curves. Therefore, 11 mineralogical associations were identified, thus 9 spectral signatures (SS) could be defined: 7 from outcropping rocks and another 2 from soils. Outcropping rocks MA Minerals SS O1 >90 % Calcite SSO1 O2 >90 % Dolomite SSO2 O3 Calcite > Dolomite SSO3-4 O4 Dolomite > Calcite O5 Calcite > Clay Minerals SSO5 O6 Calcite > Malachite SSO6 O7 >90 % Quartz (± goethite) SSO7 O8 > 90 % Gibbsite SSO8 Soils S1 Chlorite/vermic +illite +Q SSS1-2 S2 Chlorite/vermic +illite +Q + talc S3 Chlorite/vermic +illite +Q + gibbsite SSS3