Integrated carbonate-siliciclastic sediment-routing systems in the Gulf of Aqaba, Red Sea

Abstract Source-to-sink studies commonly assume independent sediment routing systems for siliciclastics and carbonates. This study integrates satellite-derived topography, imagery, swath multibeam bathymetry, and field observations to characterize a mixed carbonate-siliciclastic routing system from source to sink in the Gulf of Aqaba, northern Red Sea. The study area is lined by ephemeral desert streams (wadis) that deliver pulses of sediment to the shelf and basin during flash floods. We find that where wadis are distributary at the coast, they deposit amalgamated fan deltas associated with a continuous fringing reef, a narrow continental shelf, and a smooth line-fed slope system devoid of major submarine canyons or fans. Where knickpoints have migrated to the shoreline or into active wadi channels, the fringing reef is bisected by reentrants (sharms), there is no continental shelf, and the slope is composed of a rugged assortment of canyons and ridges. Development of sharms is the net effect of erosion by headward knickpoint migration and construction by differential aggradation on the shelf. Submarine fans linked to shelf-incising canyons are generally larger than those associated with slope-confined canyons. Fan size strongly correlates with the catchment area of the affiliated wadi networks, linking terrigenous and marine sedimentary systems. Our study offers a window into coupled terrigenous, coastal, shelf, slope, and basinal processes that have produced a steep, narrow, mixed carbonate-siliciclastic margin. The findings presented herein build on traditional depositional models and demonstrate feedbacks between integrated carbonate and siliciclastic sediment routing systems, especially in an arid climate.