Parallel lamination formed by high-density turbidity currents

Experiments were conducted in order to investigate processes of sediment transport and deposition from sustained turbidity currents with initial volume-fraction sediment concentration of 0.20, 0.25, and 0.35. Parallel lamination was formed at bed-aggradation rates up to 4 mm s(-1) and bedload-layer sediment concentration up to 0.36. This observation contradicts the generally held assumption that parallel lamination forms only from low-density flows and at low bed-aggradation rates. This misconception illustrates a poor understanding of threshold values of grain-support mechanisms in the bedload layer. The present results bring new insight into understanding sediment transport in the deep sea and interpreting the sedimentary record.