Preliminary Study on the Dynamic Mechanism of Lacustrine Fine-grained Turbidity Deposits Based on Single Factor Flume Simulation Experiment

Key words: 
• Keywords: fine-grained turbidity currents /
• dynamic mechanism /
• physical sedimentation simulation /
• transport law /
• “new head”

Abstract: [Objective] To investigate the sorting movement and sedimentary characteristics of fine-grained sediments under the action of turbidity currents, and analyze the controlled factors of their transport distance and sediments spatial distribution. [Methods] Based on circular flume simulation experiment, the transport and deposition process of fine-grained sediments carried by turbidity currents were simulated and analyzed by controlling three conditions: initial fluid velocity, sediment concentration, and sand mud ratio, and the sedimentary dynamic mechanism was explored. [Results] The simulation results indicate that: (1) Fine-grained sediments transported by turbidity currents will experience experimental phenomena such as “water jump”, “double flow segmentation”, “lofting”, “head lifting”, and “new head” during the flow process. (2) During fluid transportation, the movement speed and distance of fine-grained sediments are influenced by the concentration difference between the fluid and the environmental fluid. (3) Factors such as initial flow velocity, water jump, and lofting control fluid flow velocity, fine-grained sediments transport distance, and spatial distribution. (4) The “new head” phenomenon causes the sand bodies carried by the fluid to become discontinuous, isolated or dispersed. [Conclusions] According to the “new head” phenomenon in the simulation process, the causes of dispersed sand bodies are speculated, which has certain guiding significance for the study of the formation and distribution of dispersed sand bodies.