Mapping of high pressure metamorphics in the As Sifah region, NE Oman using ASTER data

Abstract

The high pressure metamorphic zone of As Sifah area in the Saih Hatat window, NE Oman plays a vital role to study global tectonic setting, metamorphism, transport direction and age of initial ophiolite emplacement. Scientists and researchers are keen in determining the protolith, structural evolution, and timing and metamorphic conditions of the Saih Hatat area. In this study, mapping of the metamorphic zone and discrimination of associated rock formations occurred in the As Sifah region is carried out using visible and near infrared–shortwave infrared (VNIR–SWIR) spectral bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and well known image processing methods such as image decorrelation, Principal Component Analysis (PCA) and Spectral Angel Mapper (SAM). The study delineated the region of metamorphic zone and discriminated the different metamorphic and carbonate rocks of the study area characterized by hydroxyl (OH) and carbonate bearing minerals. The assessment of accuracy for the occurrence and spatial distribution of major lithological units provided the overall accuracy of 96.06% with Kappa Coefficient=0.95 in the matrix of Maximum Likelihood (ML) and compared with the Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) algorithms. The occurrence of such minerals are detected and confirmed by SAM supervised classification method. The study also describes the spectral character of metamorphic and carbonates minerals. The metamorphic zone and associated rock types interpreted over the images are verified in the field and checked for their occurrences and spatial distributions. The occurrence of CO3 bearing carbonate minerals and OH bearing metamorphic minerals are confirmed further under microscope, XRD analysis and PIMA spectral measurements in the laboratory studies. The study proved sensor capability of ASTER to discriminate metamorphic rocks from associated formations and detection of different mineral occurrences. It is recommended to use the studied technique to map metamorphic zone occurred in the rugged topography, where it is difficult to do conventional geological mapping in similar arid regions.