TRACING ALONG-STRIKE STRUCTURAL CONTINUITY IN THE NEOPROTEROZOIC ALLAQI-HEIANI SUTURE, SOUTHERN EGYPT USING PRINCIPAL COMPONENT ANALYSIS (PCA), FAST FOURIER TRANSFORM (FFT), AND REDUNDANT WAVELET TRANSFORM (RWT) OF ASTER DATA

We have used the Visible and Near Infrared (VNIR) and Short Wave Infrared (SWIR) bands of the Advanced Space-borne Thermal Emission and Reflectance Radiometer (ASTER) to trace along-strike structures in the ophiolite-decorated Neoproterozoic Allaqi-Heiani Suture in southern Egypt. The suture is E-trending in the west, changes to N-trending in its central part, and E-trending further east. The western part of the suture is defined by a fold and thrust belt dominated by an autochthon in the south followed by a southern, central and northern allochthons that were emplaced from north to south. Tracing along-strike structures in the Allaqi-Heiani Suture has been a challenging task due to structural complexity and change of structural style.

Principal component analysis (PCA), Fast Fourier Transform (FFT), and Redundant Wavelet Transform (RWT) are used to identify distinctive markers, including ophiolite components such as talc carbonate schist and serpentinite that have been used to trace along-strike continuation in the Allaqi-Heiani Suture. (1) The PCA is performed on the 9 X 9 covariance matrix of the ASTER VNIR and SWIR bands. PC5 is selected because the ophiolite components and the Neoproterozoic ductile structures are best emphasized. (2) The FFT is performed on PC5 to reduce noises and mosaicking boundaries of the ASTER scenes. (3) The RWT is performed to enhance the contrast between the distinctive markers and the surrounding rock types.

This work helped in tracing structures along the Allaqi-Heiani Suture and revealed structural features that have not been identified before: (1) Some folds associated with the E-trending fold and thrust belts are doubly-plunging and might be sheath folds associated with nappe emplacements. (2) Truncation of structures associated with the E-trending fold and thrust belts occurs along N-trending dextral strike-slip shear zones that swing at their extreme ends to become parallel to the truncated structures. (3) Some folds close to the strike-slip shear zones indicate E-W shortening. (4) Presence of N- and NE-trending brittle faults younger than the Neoproterozoic ductile structures.