Mapping lithological and mineralogical units using hyperspectral imagery

Abstract

Hyperspectral images such as the Earth Observer-1 (EO-1) provides an efficient method of mapping surface mineralogy because it can measures the energy in narrower bands compared with multispectral sensors. Kirkuk anticline which located in northern Iraq is one of the most petroleum-rich provinces. It is an asymmetrical, cylindrical anticline, with a fold axis trends towards North West- East, South East. Tectonically, Kirkuk anticline is located in the Low Folded Zone of the Foreland Fold Belt which belongs to the Zagros Collision Zone. The primary goal of the study is to apply satellite processing and techniques on the Eo-1 imagery to identify lithological and mineral units at part of Kirkuk anticline in northern Iraq. At the beginning of atmospheric influence, the EO-1 image was corrected using the FLAASH module in ENVI software. Processing of Minimum Noise Fraction (MNF) transformation was applied and then data dimensionality was reduced, as well as, the processing of pixel purity index (PPI) was extended to spatial reduction. This study tested the potential of spectral angle mapper supervised classification (SAM) classification for mapping the lithological and mineral units using the Hyperion imagery. Three different sources of endmembers or spectra were used for SAM classifications. Source one: Is done by Analytical Spectral Devices (ASD) field Spectrometer in spectral analysis laboratory (Remote Sensing Center- Mosul University). Source two: Reference spectra have been taken from the USGS spectral library. Source three: Extracting endmembers from the purest pixels in the Hyperion image, which was done by applying (Minimum noise fraction) and (pixel purity index). The endmembers were provided and generated as the training area for SAM classification. The present findings indicate the great potential of EO-1 data for mapping the distribution of alteration minerals and lithological units in part of Kirkuk anticline. The classified Hyperion image shows that Jarosite and Illite are the most dominant altered minerals. In addition, the main lithological units of the upper member of Fatha formation are exposed in the central core of Kirkuk anticline with small outcrops scattered towards the flanks. It has been observed that the location of the main lithological unit is in full conformity with the geological map.