Remote sensing-guided stratigraphic dissection of an Ediacaran terrestrial molasse basin (Kareim basin, Egypt), with implications for sedimentary evolution

Abstract

The Kareim basin in the Central Eastern Desert is one of the largest Ediacaran post-amalgamation (Hammamat) basins in Egypt. It formed at a time of extensional tectonism (600 ± 20 Ma) in the northern Arabian-Nubian Shield. The Kareim basin preserves a ~6500 m fill of rapidly deposited alluvial fan and lake sediments. Due to monotonous lithology and complex facies variations the stratigraphic architecture of this and other large Hammamat basins is poorly known. In this study, LANDSAT 8 (OLI) data for the Kareim was processed to provide best band ratio and PCA images that allow tracing of sandstone-dominant and conglomerate-dominant packages, revealing a configuration of eight new stratigraphic units (Units 1–8). Units 1–3 are basinwide, while Units 4–8 are localized and partly bounded by intraformational angular unconformities that formed during syn-sedimentary tectonism. Fan palaeoslopes and palaeocurrents were W-directed in Units 1–3, then switched to SW- and S-directed in later units, implying that the provenance areas lay east and north of the basin, not south as in previous basin evolutionary models. This study provides the first RS-guided stratigraphic dissection of a Hammamat basin, and provides a sensitive tool for detecting intraformational unconformities in basins filled with monotonous molasse sequences. It paves the way for the sequence stratigraphic analysis of the Egyptian Hammamat basins.