Relación entre la respuesta espectral (visible - infrarrojo cercano) y la composición mineralógica de materiales sedimentarios del borde occidental de la Cuenca del Duero

Abstract

The mineralogical composition and the spectral response of 40 samples from the western Duero Basin were studied through laboratory reflectance spectroscopy (covering the 400 to 2,500 nm wavelength interval) and X-ray diffraction analysis, in order to determine the relationships between spectral curves and mineralogy. The mineralogical composition is mainly characterised by the presence of silicates and calcite. Silicates are quartz and phyllosilicates with variable amounts of feldspars. All the phyllosilicates are dioctaedric and the main associations identified are: vermiculite-illite-(+- kaolinite), illite-kaolinite and illite-smectite-kaolinite (+-palygorskite), being more frequent the last one. According to the position, shape and intensity of the absorption bands located in the spectral curves obtained from laboratory reflectance spectroscopy in the visible and near-infrared (V-NIR) portion of the electromagnetic spectrum, seven groups of samples can be differentiated. From the obtained results, it can be possible to determine, in general terms, the mineralogical composition of samples from their spectral curves, due to the relationship between the mineralogical composition and spectral response.