Multispectral mapping of evaporite minerals using ASTER data: A methodological comparison from central Turkey

Evaporites are regarded as industrial raw materials with high economic value and are represented by chemical sedimentary rocks deposited in terrestrial and marine environments. Evaporite deposits rich in calcium sulphate, such as gypsum and anhydrite, are typically formed under arid climate conditions. These rocks are very important not only in paleo-environmental and paleo-climatic studies but also for oil and natural gas exploration as they may form trap where such hydrocarbons are accumulated. Some of the central Anatolian Tertiary basins such as Çankırı-Çorum, Sivas, Ulukışla, Tuz Gölü, Haymana and Beypazarı basins host outcrops of various terrestrial and marine evaporite deposits. In this study, gypsum minerals in the Aksaray and Niğde provinces (central Turkey), was mapped with ASTER imagery using band rationing, decorrelation stretching (DECOR), feature-oriented principal components (FOPCA) and sulphate index methods. Geochemical and spectroradiometer measurements were taken on samples collected during the field studies. Accuracy assessments using the maximum likelihood technique yielded highly accurate results (average 86%) and the best results were obtained from FOPCA and DECOR methods. Results were also checked with the field studies...