The use of thermal infrared multispectral scanner data for geochronologic mapping of the cima volcanic field,san bernardino,california

Abstract

The use of the Thermal Infrared Multispectral Scanner(TIMS)as a tool for geologic mapping of a portion of the Cima Volcanic Field,San Bernardino County,California was investigated.TIMS data received from the Jet Propulsion Laboratory were reformatted and analyzed in the LARSFRIS computer processing environment at the Indiana State University Remote Sensing Laboratory.Classifications of the Cima Field lava flows were produced from three data sets derived from the raw TIMS data(radiance,emissivity,decorrelation stretch).Earlier chemical analyses have shown that Tertiary lava flows are consistency higher in bulk silica than the Quaternary lava flows.It was hypothesized that the TIMS system would be able to identify this trend and thus be a good tool for geologic mapping in the Cima Field area.The classifications were analysed in order to understand the nature of the information contained in each of the data sets.Classifications suing each of the original data sets along with classifications formed from combinations of the three original data sets were produced in an attempt to best differentiate features of interest in the Cima Volcanic Field study area.The best classification produced allows an analyst to discriminate the Tertiary lava flows from the Quaternary lava flows with acceptable accuracy.It also allowed the discrimination between the Quaternary lava flows through the use of textures created by the mixing of colors in the image product.This classification corresponded well to the existing geologic maps of the Cima Field Study area.The best classification did not prove to be the one using all of the available information but rather utilizing all of the radiance and emissivity bands and band 1 of the decorrelation stretch data set.Bands 2 and 3 of the decorrelation stretch data set tended to amplify geomorphic and scanner noise,thus they were poor to use for classification.The spectral relationships within the data sets were analysed in the light of geochemical and radiometric information culled from the literature on the Cima field.One trend which was identified in the data sets consisted of increasing radiances in the lava flows with decreasing age.This trend could have been associated with the geochemistry or with geomorphology of the study area.Future considerations for research are presented along with recoomendations for the use of TIMS data and possible design changes for an improved thermal scanner.