Integration of Landsat-8 and Reflectance Spectroscopy data for Mapping of Late Neoproterozoic Igneous Ring Complexes in an Arid Environment: a Case Study of Gebel El-Bakriyah Area, Eastern Desert, Egypt

The present work aims to enhance the utilization of Landsat-8 data in geological mapping when they are paired with spectroscopic measurements and field observations. This is applied to map and differentiate the different plutonic rocks in the Gebel El-Bakriyah pluton, a peculiar igneous body in the central Eastern Desert of Egypt. Therefore, we use a combination of remote sensing techniques such as principal component analysis (PCA), band ratios, fusion technique, and spectroscopic measurements to interpret igneous lithologies, and produce a new geologic map of the Gebel El-Bakriyah area. A false-color composite principal component image PC1, PC2, and PC3 in red, green, and blue (RGB) discriminates between alkali feldspar granite, syenogranite, and younger gabbro. In general, the spectral profiles of granites exhibit three distinct absorption features in the 1.4, 1.9, and 2.2 μm wavelength regions. These features are attributed mainly to altered mineral products such as kaolinite, sericite, and chlorite. The spectral profiles of pink and alkali feldspar granites show a broad absorption feature at 0.9 μm, which is attributed to a considerable Fe content. The spectral profiles of fresh, younger gabbros exhibit absorption features around 1 μm and 2.2 μm. A false-color composite image provides the most accurate discrimination of the three varieties of younger granites with band ratios of 7/4, 6/3, and 3/1 in RGB. The data that appear in the present work strengthen the usefulness of Landsat-8 imagery and spectroscopic measurements as a prevailing grouping to discriminate and map Neoproterozoic shield rocks in the Eastern Desert of Egypt.