Abstract
The deposition of a classic turbidite by a surge-type turbidity current, as envisaged by conceptual models, is widely considered a discrete event of continuous sediment accumulation at a falling rate by the gradually waning density flow. Here, we demonstrate, on the basis of a high-resolution advanced numerical CFD (computational fluid dynamics) simulation and rock-record examples, that the depositional event in reality involves many brief episodes of nondeposition. The reason is inherent hydraulic fluctuations of turbidity current energy driven by interfacial Kelvin-Helmholtz waves. The experimental turbidity current, with realistic grain-size composition of a natural turbidite, used only 26 to 33% of its in-place flow time for deposition, while the remaining time went to the numerous episodes of sediment bypass and transient erosion. The general stratigraphic notion of a gross incompleteness of sedimentary record may then extend down to the deposition time scale of a single turbidite.
Highlights
Turbidity currents are subaqueous turbulent sediment-gravity flows that deliver huge volumes of sand and other clastic sediment to the deep-sea floor [1,2,3]
Can the deposition of sediment by a uniformly fed continuous flow be in reality discontinuous?. We address this contentious issue by a high-resolution advanced computational fluid dynamics (CFD) simulation of a natural-scale, average surge-type turbidity current
The K-H waves in turbidity currents have long been considered as important for the interfacial entrainment of ambient water, but with no obvious direct impact predicted for the bedload transport [7, 27]
Summary
Turbidity currents are subaqueous turbulent sediment-gravity flows that deliver huge volumes of sand and other clastic sediment to the deep-sea floor [1,2,3]. There is probably no other coarse-clastic depositional system on Earth that would accumulate hundreds to thousands of meters of sediment by a simple repetition of one and the same discrete rare event—a turbidity current. These systems vary enormously in their dimensions and morphodynamics [3, 14], partly because the turbidity currents differ considerably in their hydraulic properties and behavior [10, 15], the great interest in turbidites and their internal vertical succession of grain size and sedimentary structures, interpreted as the in-place record of flow behavior and evolving bedform pattern [15,16,17,18,19,20,21,22]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
