Spectral discrimination of ignimbritic rocks in the Deseado Massif using Landsat-TM and GER-S-IRIS data

Shows some basic approaches to discriminate ignimbrite type pyroclastic flow deposits in Landsat Thematic imagery of semi-arid areas. Beside certain topographical and tectonical features which already describe ignimbrites and associated pyroclastic flows in those environments, the authors´ interest is focused on the influence of specific mineralogical and depositional characteristics on the spectral reflectance response. Spectral signatures in the visible and near infrared region of various fresh and weathered samples as well as desert varnish were recorded using a laboratory spectroscope to determine the factors controlling their proper response in all Thematic Mapper bands. Whole rock geochemistry data, microscopical studies and surface interpretations of the samples documented certain properties which might cause different spectral signatures also of geochemically mostly equivalent rocks